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72 results on '"F. La Forgia"'

1. Bilobate comet morphology and internal structure controlled by shear deformation

Author: Carsten Güttler, F. Preusker, Dennis Bodewits, Alice Lucchetti, Philippe Lamy, J.-B. Vincent, H. U. Keller, D. Nébouy, Björn Davidsson, A. T. Auger, Matteo Massironi, Stefano Debei, Cecilia Tubiana, F. La Forgia, Stubbe F. Hviid, Hans Rickman, M. De Cecco, Luca Penasa, M. A. Barucci, L. M. Lara, Nilda Oklay, C. Matonti, Nicholas Attree, J. L. Bertaux, Olivier Groussin, Sophie Viseur, Monica Lazzarin, Maurizio Pajola, Imre Toth, Francesco Marzari, Ivano Bertini, R. Rodrigo, Jakob Deller, Sylvain Bouley, Sonia Fornasier, Holger Sierks, V. Da Deppo, J. J. Lopez-Moreno, Wing-Huen Ip, Laurent Jorda, Giampiero Naletto, G. Cremonese, Frank Scholten, Marco Fulle, Xian Shi, Stefano Mottola, P. J. Gutierrez, Detlef Koschny, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Faculty of Natural Sciences [Stirling], University of Stirling, DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), Dipartimento di Fisica e Astronomia 'Galileo Galilei', CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Physics [Auburn], Auburn University (AU), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Institute of Astronomy [Taiwan] (IANCU), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Dipartimento di Geoscienze [Padova], Department of Physics and Astronomy [Uppsala], Uppsala University, Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), national funding agency of Germany (DLR), national funding agency of France (CNES), national funding agency of Italy (ASI), national funding agency of Spain (MEC), national funding agency of Sweden (SNSB), ESA Technical Directorate, Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), IMPEC - LATMOS, Max-Planck-Institut für Sonnensystemforschung (MPS), Universita degli Studi di Padova, Consiglio Nazionale delle Ricerche [Roma] (CNR), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), European Space Agency (ESA)-European Space Agency (ESA), California Institute of Technology (CALTECH)-NASA, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Technische Universität Braunschweig [Braunschweig], Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), and Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: Solar System, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010504 meteorology & atmospheric sciences, 3d analysis, Comet, Geophysics, 010502 geochemistry & geophysics, 01 natural sciences, rosetta, Shear (geology), [SDU]Sciences of the Universe [physics], 13. Climate action, General Earth and Planetary Sciences, Sublimation (phase transition), Water ice, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Earth and Planetary Sciences (all), Geology, 0105 earth and related environmental sciences
Abstract: Bilobate comets—small icy bodies with two distinct lobes—are a common configuration among comets, but the factors shaping these bodies are largely unknown. Cometary nuclei, the solid centres of comets, erode by ice sublimation when they are sufficiently close to the Sun, but the importance of a comet’s internal structure on its erosion is unclear. Here we present three-dimensional analyses of images from the Rosetta mission to illuminate the process that shaped the Jupiter-family bilobate comet 67P/Churyumov–Gerasimenko over billions of years. We show that the comet’s surface and interior exhibit shear-fracture and fault networks, on spatial scales of tens to hundreds of metres. Fractures propagate up to 500 m below the surface through a mechanically homogeneous material. Through fracture network analysis and stress modelling, we show that shear deformation generates fracture networks that control mechanical surface erosion, particularly in the strongly marked neck trough of 67P/Churyumov–Gerasimenko, exposing its interior. We conclude that shear deformation shapes and structures the surface and interior of bilobate comets, particularly in the outer Solar System where water ice sublimation is negligible. The shape and internal structure of bilobate comet 67P is controlled by shear deformation inducing mechanically driven erosion along shear fracture networks, according to a 3D analysis of images from the Rosetta mission.
Published: 2019

2. Observational constraints to the dynamics of dust particles in the coma of comet 67P/Churyumov–Gerasimenko

Author: Pamela Cambianica, Giampiero Naletto, G. Cremonese, Francesco Marzari, F. La Forgia, I. Bertini, Carsten Güttler, Marco Fulle, Monica Lazzarin, Fernando Moreno, Sabrina Ferrari, Stavro Ivanovski, Alessandra Rotundi, Francesca Ferri, Holger Sierks, Alice Lucchetti, Cecilia Tubiana, V.V. Zakharov, Maurizio Pajola, E. Frattin, Luca Penasa, Agenzia Spaziale Italiana, European Commission, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), and Junta de Andalucía
Subjects: Physics, Comets: individual, Earth and Planetary Astrophysics (astro-ph.EP), 010504 meteorology & atmospheric sciences, Dust particles, photometric [Techniques], Library science, Techniques: image processing, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, individual [Comets], 01 natural sciences, Space and Planetary Science, Methods: data analysis, 0103 physical sciences, image processing [Techniques], Christian ministry, Techniques: photometric, Astrophysics::Earth and Planetary Astrophysics, data analysis [Methods], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Astrophysics - Earth and Planetary Astrophysics
Abstract: In this work, we aim to characterize the dust motion in the inner coma of comet 67P/Churyumov-Gerasimenko to provide constraints for theoretical 3D coma models. The OSIRIS camera on-board the Rosetta mission was able for the first time to acquire images of single dust particles from inside the cometary coma, very close to the nucleus. We analyse a large number of particles, performing a significant statistic of their behaviour during the post-perihelion period, when the spacecraft covered distances from the nucleus ranging between 80 and 400 km. We describe the particle trajectories, investigating their orientation and finding highly radial motion with respect to the nucleus. Then, from the particle brightness profiles, we derive a particle rotational frequency of ν < 3.6 Hz, revealing that they are slow rotators and do not undergo fragmentation. We use scattering models to compare the observed spectral radiance of the particles with the simulated ones in order to estimate their size, finding values that range from millimetres up to centimetres. The statistics performed in this paper provide useful parameters to constrain the cometary coma dynamical models. © 2021 The Author(s)., OSIRIS was built by a consortium of the Max-Planck-Institut fur Sonnensystemforschung in Gottingen, Germany; CISAS-University of Padova, Italy; the Laboratoire d'Astrophysique de Marseille, France; the Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain; the Research and Scientic Support Department of the European Space Agency, Noordwijk, The Netherlands; the Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain; the Universidad Politechnica de Madrid, Spain; the Department of Physics and Astronomy of Uppsala University, Sweden; and the Institut fur Datentechnik und Kommunikationsnetze der Technischen Universit at Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), Italy (ASI), France (CNES), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. GIADA was built by a consortium led by the Univ. Napoli Parthenope INAF-Oss. Astr. Capodimonte, in collaboration with the Inst. de Astrofisica de Andalucia, Selex-ES, FI and SENER. GIADA was managed and operated at INAF-IAPS. GIADA was funded and managed by the Agenzia Spaziale Italiana, IT, with the support of the Spanish Ministry of Education and Science MEC, ES. We thank the ESA teams at ESAC, ESOC, and ESTEC for their work in support of the Rosetta mission. This research has been supported by the Italian Space Agency (ASI) within the ASI-INAF agreements I/032/05/0, I/024/12/0, and ASI 2020-4-HH.0. Fernando Moreno acknowledges financial support from the Spanish plan National de Astrofisica y Astronomia LEONIDAS project RTI2018-095330-B-100, project P18-RT-1854 from Junta de Andalucia, and the Centro de Excelencia Severo Ochoa Program under grant SEV-2017-0709. Elisa Frattin acknowledges funding from Italian Ministry of Education, University and Research (MIUR) through the `Dipartimenti di eccellenza' project Science of the Universe.
Published: 2021

3. Characterization of V-type asteroids orbiting in the middle and outer main belt

Author: Mauro Barbieri, F. La Forgia, Alessandra Migliorini, M. C. De Sanctis, Monica Lazzarin, Daniela Lazzaro, Dino Mesa, and Tatiana A. Michtchenko
Subjects: Physics, 010504 meteorology & atmospheric sciences, asteroids: individual: Vesta, techniques: spectroscopic telescopes minor planets, Astronomy and Astrophysics, 01 natural sciences, Astrobiology, Characterization (materials science), Space and Planetary Science, Asteroid, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: We present new spectral observations using ground-based telescopes of 23 putative V-type asteroids, selected according to colour surveys in the visible from the Moving Objects Catalogue of the Sloan Digital Sky Survey and near-infrared from the Moving Objects VISTA catalogue. 10 asteroids are orbiting in the middle main belt, while five in the outer part of the main asteroid belt. For the observed asteroids, we assign a taxonomical classification and confirm the basaltic nature for 16 of them. The high-quality spectra in the UV range, obtained with the X-Shooter spectrograph at ESO, allowed the identification of the Fe2+ forbidden transition of pyroxene for 10 asteroids. This band is centred at 506.5 nm, and it is diagnostic of the Ca-content in the pyroxene form. We determined a low Fe-content composition for asteroids (2452) Lyot, (5758) Brunini, (7675) Gorizia, (9197) Endo, (22308) 1990 UO4, (36118) 1999 RE135, (66905) 1999 VC160, and (189597) 2000 WG119, and a composition more rich in Fe for asteroids (75661) 2000 AB79 and (93620) 2000 UQ70. We also present a dynamical investigation of V-type asteroids in the middle and outer main belt. The principal finding of these simulations is that the middle and outer V-types are more likely to be associated with some families, which were considered as possibly originated from the break up of a partially or totally differentiated parent body by diverse studies. This reinforces the hypothesis that the identified V-type in the region were not originated from (4) Vesta and that the number of differentiated objects in the middle and outer main belt must have been much larger than previously assumed.
Published: 2021

4. Time evolution of dust deposits in the Hapi region of comet 67P/Churyumov-Gerasimenko

Author: D. Bodewits, Pamela Cambianica, Maurizio Pajola, Michael Küppers, Alice Lucchetti, Imre Toth, Holger Sierks, E. Frattin, Monica Lazzarin, Sonia Fornasier, F. La Forgia, E. Simioni, Giampiero Naletto, Luca Penasa, Pedro J. Gutiérrez, Gabriele Cremonese, Cecilia Tubiana, Marco Fulle, Matteo Massironi, Francesca Ferri, Francesco Marzari, J. B. Vincent, Stefano Mottola, H. U. Keller, Carsten Güttler, Cecilia Ceccarelli, Ivano Bertini, Ekkehard Kührt, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), German Centre for Air and Space Travel, Centre National de la Recherche Scientifique (France), Agenzia Spaziale Italiana, Ministerio de Ciencia, Innovación y Universidades (España), and Government of Sweden
Subjects: 010504 meteorology & atmospheric sciences, Comet, Astrophysics, Atmospheric sciences, comets: general / comets: individual: 67P/Churyumov-Gerasimenko / methods: data analysis / methods: numerical, 7. Clean energy, 01 natural sciences, methods: numerical, comets: general – comets: individual: 67P/Churyumov-Gerasimenko – methods: data analysis – methods: numerical, individual: 67P/Churyumov-Gerasimenko [Comets], 0103 physical sciences, data analysis [Methods], Comets: general, Comets: individual: 67P/Churyumov-Gerasimenko, Methods: data analysis, Methods: numerical, Ejecta, Pebble, 010303 astronomy & astrophysics, Southern Hemisphere, 0105 earth and related environmental sciences, Physics, [PHYS]Physics [physics], numerical [Methods], Accretion (meteorology), comets: general, general [Comets], comets: individual: 67P/Churyumov-Gerasimenko, Astronomy and Astrophysics, Mass ratio, methods: data analysis, 13. Climate action, Space and Planetary Science, Erosion, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Mass fraction
Abstract: Aims. We provide a measurement of the seasonal evolution of the dust deposit erosion and accretion in the Hapi region of comet 67P/Churyumov-Gerasimenko with a vertical accuracy of 0.2-0.9 m. Methods. We used OSIRIS Narrow Angle Camera images with a spatial scale of lower than 1.30 m px-1 and developed a tool to monitor the time evolution of 22 boulder heights with respect to the surrounding dust deposit. The tool is based on the measurement of the shadow length projected by the boulder on the surrounding pebble deposit. Assuming the position of the boulders does not change during the observational period, boulder height variations provide an indication of how the thickness of the surrounding dust layer varies over time through erosion and accretion phenomena. Results. We measured an erosion of the dust deposit of 1.7 ± 0.2 m during the inbound orbit until 12 December, 2014. This value nearly balances the fallout from the southern hemisphere during perihelion cometary activity. During the perihelion phase, the dust deposit then increased by 1.4 ± 0.8 m. This is interpreted as a direct measurement of the fallout thickness. By comparing the erosion rate and dust volume loss rate at the Hapi region measured in the coma, the fallout represents ~96% in volume of the ejecta. The amount of the eroded pristine material from the southern hemisphere, together with its subsequent transport and fallout on the nucleus, led us to discuss the pristine water ice abundance in comet 67P. We determine that the refractory-to-ice mass ratio ranges from 6 to 110 in the perihelion-eroded pristine nucleus, providing a pristine ice mass fraction of (8 ± 7)% in mass. © 2020 ESO., OSIRIS was built by a consortium of the Max-Planck Institut fur Sonnensystemforschung, in Guttingen, Germany, CISAS University of Padova, Italy, the Laboratoire de Astrophysique de Marseille, France, the Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain, the Research and Scientific Support Department of the European Space Agency, Noordwijk, The Netherlands, the Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, the Universidad Politechnica de Madrid, Spain, the Department of Physics and Astronomy of Uppsala University, Sweden, and the Institut fur Datentechnik und Kommunikationsnetze der Technischen Universitat Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. We thank the ESA teams at ESAC, ESOC and ESTEC for their work in support of the Rosetta mission. We made use of Arcgis 10.3.1 software together with the Matlab, Java, and ImageJ software to perform our analysis. I.T. acknowledges the support from project GINOP-2.3.2-15-2016-00003 "Cosmic effects and hazards".
Published: 2020

5. Dust environment model of the interstellar comet 2i/borisov

Author: J. Nicolas, E. Bryssinck, Marco Fulle, A. Mantero, D. Carosati, Giannantonio Milani, M. Maestripieri, G. Arlic, Monica Lazzarin, E. Guido, P. Ochner, M. T. Capria, S. Di Rubbo, P. Cambianica, A. Aletti, Paolo Bacci, R. Bacci, G. Cremonese, A. Valvasori, G. Munaretto, W. Boschin, R. Trabatti, D. Castellano, F. Kugel, C. Perrella, Alessandra Migliorini, F. La Forgia, R. Ligustri, M. Facchini, L. Buzzi, and ITA
Subjects: Physics, Planetary science, Comets, Space and Planetary Science, Interstellar comet, Astronomy and Astrophysics, Astrobiology
Abstract: 2I/Borisov is the first interstellar comet discovered on 2019 August 30, and it soon showed a coma and a dust tail. This study reports the results of images obtained at the Telescopio Nazionale Galileo telescope, on La Palma - Canary Islands, in 2019 November and December. The images have been obtained with the R filter in order to apply our dust tail model. The model has been applied to the comet 67P/Churyumov-Gerasimenko and compared to the Rosetta dust measurements showing a very good agreement. It has been applied to the comet 2I/Borisov, using almost the same parameters, obtaining a dust environment similar to that of 67P/Churyumov-Gerasimenko, suggesting that the activity may be very similar. The dust tail analysis provided a dust-loss rate Qd ≍ 35 kg s-1 in 2019 November and Qd ≍ 30 kg s-1 in 2019 December.
Published: 2020

6. Spectrophotometric variegation of the layering in comet 67P/Churyumov-Gerasimenko as seen by OSIRIS

Author: Cesare Barbieri, W-H. Ip, Pedro J. Gutiérrez, Jakob Deller, Björn Davidsson, D. Bodewits, Gloria Tognon, R. Rodrigo, F. La Forgia, V. Petropoulou, Philippe Lamy, Prasanna Deshapriya, H. U. Keller, Cecilia Tubiana, M. A. Barucci, Holger Sierks, V. Da Deppo, Carsten Güttler, Matteo Massironi, Marco Fulle, Imre Toth, Michel Franceschi, Sabrina Ferrari, Giampiero Naletto, Alice Lucchetti, Detlef Koschny, M. De Cecco, E. Frattin, Sonia Fornasier, J. J. Lopez-Moreno, Monica Lazzarin, Maurizio Pajola, Ivano Bertini, Luca Penasa, Luisa Lara, Francesca Ferri, Francesco Marzari, Pamela Cambianica, Jean-Loup Bertaux, Gabriele Cremonese, Stefano Debei, Xian Shi, Stefano Mottola, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Dipartimento di Geoscienze [Padova], CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Department of Physics [Auburn], Auburn University (AU), CNR Institute for Photonics and Nanotechnologies (IFN), Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Università degli Studi di Padova = University of Padua (Unipd), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), NASA-California Institute of Technology (CALTECH), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Agence Spatiale Européenne = European Space Agency (ESA), German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), IMPEC - LATMOS, Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Technische Universität Braunschweig [Braunschweig], Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Tognon, Gloria, Ferrari, S., Penasa, L., La Forgia, F., Massironi, M., Naletto, G., Lazzarin, M., Cambianica, P., Lucchetti, A., Pajola, M., Ferri, F., Güttler, C., Davidsson, B., Deshapriya, P., Fornasier, S., Mottola, S., Tóth, I., Sierks, H., Lamy, P. L., Rodrigo, R., Koschny, D., Barbieri, C., Barucci, M. A., Bertaux, J. -L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Deller, J., Franceschi, M., Frattin, E., Fulle, M., Gutiérrez, P. J., Ip, W. -H., Keller, H. U., Lara, L. M., López-Moreno, J. J., Marzari, F., Petropoulou, V., Shi, X., and Tubiana, C.
Subjects: Brightness, 010504 meteorology & atmospheric sciences, Outcrop, Multispectral image, Narrow angle, Astrophysics, 01 natural sciences, WATER ICE, NUCLEUS, individual: 67P/Churyumov-Gerasimenko [Comets], Methods: data analysis, 0103 physical sciences, data analysis [methods], medicine, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Comets: individual: 67P/Churyumov-Gerasimenko, Physics, Multispectral data, biology, general [Comets], Astronomy and Astrophysics, biology.organism_classification, Lobe, Comets: general, medicine.anatomical_structure, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], comets: general – comets: individual: 67P/Churyumov-Gerasimenko – methods: data analysis, Osiris, Layering, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Between August 2014 and September 2016, the ESA space mission Rosetta escorted comet 67P/Churyumov-Gerasimenko (67P) during its perihelion passage. The onboard OSIRIS Narrow Angle Camera (NAC) acquired high-resolution multispectral images of the cometary surface. These datasets allowed a characterization of the spectrophotometric variegation of the layering of the large lobe, correlated with the layer structural elevation. Aims. We perform a spectrophotometric characterization of the outcropping stratification of the small lobe of 67P as a function of its structural elevation, and consequently, a spectrophotometric comparison of the layered outcrops of the two lobes. Methods. We selected two sequences of post-perihelion OSIRIS NAC images (similar to 2.4 au outbound to the Sun), from which we built up two multispectral images, framing an extended geological section of the onion-like stratification of the small lobe. Then we classified the consolidated areas of the outcropping and the relative coarse deposits that were identified in the multispectral data with a two-class maximum likelihood method. For this, we defined the classes as a function of the structural elevation of the surface. Results. As a result, we identified a brightness variegation of the surface reflectance that is correlated with the structural elevation. The outer class, which is located at higher elevations, appears darker than the inner class. This fits previously obtained results for the large lobe. The reflectance values of the nucleus of 67P tend to decrease with increasing structural elevation. Conclusions. The observed spectrophotometric variegation can be due to a different texture as well as to a different content of volatiles and refractories. We suggest that the outer outcrops appear darker because they have been exposed longer, and the inner outcrops appear brighter because the surface has been more effectively rejuvenated. We interpret this variegation as the result of an evolutionary process.© ESO 2019, We are grateful to Andrea Longobardo for suggestions and corrections that improved our paper. OSIRIS was built by a consortium of the Max-Planck-Institut fur Sonnensystemforschung, Gottingen, Germany, CISAS - University of Padova, Italy, the Laboratoire d'Astrophysique de Marseille, France, the Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain, the Research and Scientific Support Department of the European Space Agency, Noordwijk, The Netherlands, the Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, the Universidad Politechnica de Madrid, Spain, the Department of Physics and Astronomy of Uppsala University, Sweden, and the Institut fur Datentechnik und Kommunikationsnetze der Technischen Universitat Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged.
Published: 2019

7. Multidisciplinary analysis of the Hapi region located on Comet 67P/Churyumov–Gerasimenko

Author: Wing-Huen Ip, Philippe Lamy, Carsten Güttler, F. La Forgia, Nilda Oklay, R. Rodrigo, Z. Y. Lin, Dennis Bodewits, Stefano Debei, V. Da Deppo, H. U. Keller, Luca Penasa, Jakob Deller, Maurizio Pajola, Alice Lucchetti, Gabriele Cremonese, Giampiero Naletto, Sonia Fornasier, Detlef Koschny, Marco Fulle, P. J. Gutierrez, M. De Cecco, Holger Sierks, J. J. Lopez Moreno, Francesco Marzari, J.-C. Lee, Matteo Massironi, F. Preusker, Ivano Bertini, Stubbe F. Hviid, Sabrina Ferrari, Imre Tóth, Jessica Agarwal, Pamela Cambianica, Xian Shi, Frank Scholten, Lorenza Giacomini, Jean-Loup Bertaux, M. A. Barucci, Stefano Mottola, Luisa Lara, Björn Davidsson, M. R. El Maarry, Clement Feller, Cecilia Tubiana, Monica Lazzarin, Jean-Baptiste Vincent, INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Department of Atmospheric Sciences [Taoyuan City], National Central University [Taiwan] (NCU), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Dipartimento di Geoscienze [Padova], Dipartimento di Fisica e Astronomia 'Galileo Galilei', CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), Institute of Space Science [Taiwan], Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), IMPEC - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), International Space Science Institute [Bern] (ISSI), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), Department of Physics [Auburn], Auburn University (AU), Department of Mechanical Engineering [Padova], Department of Industrial Engineering [Padova], Universita degli Studi di Padova-Universita degli Studi di Padova, University of Trento [Trento], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], INAF - Osservatorio Astronomico di Trieste (OAT), Institut d'Astronomie et d'Astrophysique [Bruxelles] (IAA), Université Libre de Bruxelles [Bruxelles] (ULB), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), European Space Agency, Swedish National Space Board, Ministerio de Educación y Ciencia (España), Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, German Centre for Air and Space Travel, Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737, Pajola, M. [0000-0002-3144-1277], Penasa, L. [0000-0002-6394-3108], Fornasier, S. [0000-0001-7678-3310], Lucchetti, A. [0000-0001-7413-3058], Vicent, J. B. [0000-0001-6575-3079], Naletto, G. [0000-0003-2007-3138], Barucci, M. A. [0000-0002-1345-0890], Bertaux, J. L. [0000-0003-0333-229X], Deller, J. [0000-0001-8341-007X], Fulle, M. [0000-0001-8435-5287], Güttler, C. [0000-0003-4277-1738], Tubiana, C. [0000-0001-8475-9898], Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), California Institute of Technology (CALTECH)-NASA, PLANETO - LATMOS, Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Université libre de Bruxelles (ULB), Agenzia Spaziale Italiana (ASI), Swedish National Space Agency (SNSA), Deutsches Zentrum für Luft- und Raumfahrt (DLR), and Centre National D'Etudes Spatiales (CNES)
Subjects: Asteroiden und Kometen, statistical [Methods], Comet, individual (67P C-G) [Comets], Comets: individual (67P C-G), Methods: data analysis, Methods: statistical, 01 natural sciences, Methods statistical, Gravitational potential, 0103 physical sciences, data analysis [Methods], 010303 astronomy & astrophysics, Southern Hemisphere, Physics, geography, geography.geographical_feature_category, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Multidisciplinary analysis, Planetengeodäsie, 67P/Churyumov–Gerasimenko Comets Rosetta Hapi, Northern Hemisphere, Astronomy, Astronomy and Astrophysics, methods: data analysis –methods: statistical – comets: individual (67P C-G), Space and Planetary Science, Ridge, individual: 67P C-G [Comets], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: By using the Rosetta/OSIRIS-NAC data set taken in 2014 August, we focus on the neck region, called Hapi, located on 67P Churyumov-Gerasimenko's Northern hemisphere. The gravitational potential and slopes of Hapi, coupled with the geological unit identification and the boulder size-frequency distributions, support the interpretation that both taluses and gravitational accumulation deposits observable on Hapi are the result of multiple cliff collapses that occurred at different times. By contrast, the fine-particle deposits observable in the central part of the study area are made of aggregates coming from the Southern hemisphere and deposited during each perihelion passage. Both the consolidated terrains on the western part of Hapi, as well as the centrally aligned ridge made of boulder-like features, suggest that Hapi is in structural continuity with the onion-like structure of the main lobe of 67P. Despite the dusty blanket observable on Hapi, its terrains are characterized by water-ice-rich components that, once repeatedly and rapidly illuminated, sublimate, hence resulting in the strong jet activity observed in 2014 August.© 2019 The Author(s)., The support of the national funding agencies of Germany (DLR), Italy (ASI), France (CNES), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged.
Published: 2019

8. Phaethon variability during December 2017 closest approach to Earth

Author: F. La Forgia, Ivano Bertini, Alessandro Siviero, Alessandra Migliorini, Monica Lazzarin, V. Petropoulou, P. Ochner, and ITA
Subjects: Physics, Near-Earth object, 010504 meteorology & atmospheric sciences, Astronomy and Astrophysics, Context (language use), Astrophysics, 01 natural sciences, Space weathering, Asteroids, Spectroscopy, Asteroids, 3200 Phaethon, Meteorite, Space and Planetary Science, Planet, Asteroid, 0103 physical sciences, 3200 Phaethon, Spectroscopy, Interplanetary spaceflight, Meteor shower, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: In the course of its last close encounter with the Earth in December 2017, the peculiar Near Earth Object (NEO) 3200 Phaethon has been the target of an international observational campaign in particular connected with the proposed mission Destiny+ (Demonstration and Experiment of Space Technology for INterplanetary voYage Phaethon fLyby dUSt science) by JAXA (Japan Aerospace Exploration Agency) to be launched in 2022. The nature of 3200 Phaethon is still debated because of its asteroidal dynamical behavior as opposed to its connection with the Geminid meteor shower, typical cometary residuals. Owing to its vicinity to our planet (Minimum Orbit Intersection Distance MOID = 0.0206 AU) it has been included also in the class of Potentially Hazardous objects and it has been extensively investigated also during its previous perihelion passages. It has been classified as B-type asteroid (Binzel et al., 2001), with different spectral slopes found by several authors in the wavelength region shortward 0.55 μ m . Many issues remain to be explored regarding the nature of this object and in this context we observed 3200 Phaethon in the course of 24 h during its last closest approach to the Earth. Low-resolution spectra at very high elevation angles (airmass 1.15 ) were acquired with the 1.22–m Asiago telescope on 2017-Dec-16 and 2017-Dec-17. The variation of the viewing geometry during these observations was also derived. We found a significant variation in Phaethon spectral slope in the wavelength range [0.33–0.64] μ m during its perigeon passage. The slope varies from − 9.1 ± 0.2 % ( / 0.1 μ m ) on 2017-Dec-16 to − 2.0 ± 0.1 % ( / 0.1 μ m ) on 2017-Dec-17. This variation seems to be related to a disappearing bluer region at high latitudes ( > 70 ∘ , close to the North pole). The spectra show also a weak absorption band around 0.43 μ m and lack the reflectance downturn at least until ∼ 0.33 μ m . The comparison with meteorites suggests compositional similarities with CI/CM unusual chondrites. We propose several scenarios that could be responsible for the variability recorded, such as possible surface variations in composition, grain-size, or the level of space weathering and thermal metamorphism. A strong and sudden variation of dust production is also discussed.
Published: 2019

9. The backscattering ratio of comet 67P/Churyumov-Gerasimenko dust coma as seen by OSIRIS onboard Rosetta

Author: Pamela Cambianica, F. La Forgia, Jean-Loup Bertaux, P. J. Gutierrez, Alice Lucchetti, E. Frattin, Alessandra Rotundi, Detlef Koschny, Pedro Hasselmann, Xian Shi, Wing-Huen Ip, Giovanna Rinaldi, Philippe Lamy, Carsten Güttler, Giampiero Naletto, Stefano Mottola, Monica Lazzarin, Marco Fulle, J. J. Lopez Moreno, Sabrina Ferrari, Nafiseh Masoumzadeh, M. A. Barucci, H. U. Keller, D. Guirado, Imre Toth, V. Petropoulou, Gábor L. Kovács, Holger Sierks, Gabriele Cremonese, M. De Cecco, Cesare Barbieri, L. M. Lara, Björn Davidsson, Jakob Deller, Dennis Bodewits, S. Ivanovsky, Francesca Ferri, Cecilia Tubiana, Luca Penasa, Jessica Agarwal, Stefano Debei, Ivano Bertini, Maurizio Pajola, Olga Muñoz, Francesco Marzari, S. Fornasier, Matteo Massironi, F. Moreno, R. Rodrigo, V. Da Deppo, German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Ministerio de Educación y Ciencia (España), Swedish National Space Agency, European Space Agency, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Universita degli Studi di Padova, INAF - Osservatorio Astronomico di Trieste (OAT), Istituto Nazionale di Astrofisica (INAF), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Dipartimento di Scienze e Tecnologie [Napoli] (DIST), Universita degli studi di Napoli 'Parthenope' [Napoli], INAF - Osservatorio Astronomico di Padova (OAPD), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Department of Physics [Auburn], Auburn University (AU), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), CNR Institute for Photonics and Nanotechnologies (IFN), Department of Industrial Engineering [Padova], University of Trento [Trento], Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Dipartimento di Geoscienze [Padova], Fulle, M. [0000-0001-8435-5287], Tubiana, C. [0000-0001-8475-9898], Güttler, C. [0000-0003-4277-1738], Pajola, M. [0000-0002-3144-1277], Rinaldi, G. [0000-0002-2968-0455], Naletto, G. [0000-0003-2007-3138], Barucci, M. A. [0000-0002-1345-0890], Bertaux, J. L. [0000-0003-0333-229X], Deller, J. [0000-0001-8341-007X], Fornasier, S. [0000-0001-7678-3310], Penasa, L. [0000-0002-6394-3108], Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), IMPEC - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), NASA-California Institute of Technology (CALTECH), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Technische Universität Braunschweig [Braunschweig], Università degli Studi di Padova = University of Padua (Unipd), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Università degli Studi di Napoli 'Parthenope' = University of Naples (PARTHENOPE), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Agence Spatiale Européenne = European Space Agency (ESA), and Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Subjects: 67P/Churyumov-Gerasimenko, Asteroiden und Kometen, 010504 meteorology & atmospheric sciences, photometry, Comet, data analysis, scattering –methods: data analysis – techniques: image processing – techniques: photometric – comets: individual: 67P/Churyumov-Gerasimenko, techniques: image processing, Astrophysics, 01 natural sciences, Photometry (optics), Scattering, techniques: photometric, individual: 67P/Churyumov-Gerasimenko [Comets], 0103 physical sciences, Churyumov–Gerasimenko, image processing [Techniques], data analysis [Methods], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, biology, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], scattering, methods: data analysis, techniques: image processing, techniques: photometric, comets: individual: 67P/Churyumov-Gerasimenko, Phase angle, scattering, photometric [Techniques], comets: individual: 67P/Churyumov-Gerasimenko, Astronomy and Astrophysics, biology.organism_classification, methods: data analysis, image processing, 13. Climate action, Space and Planetary Science, Drag, Temporal resolution, Inverse scattering problem, Osiris, individual: 67P [Comets], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Remote sensing observations of dust particles ejected from comets provide important hints on the intimate nature of the materials composing these primitive objects. The measurement of dust coma backscattering ratio, BSR, defined as the ratio of the reflectance at phase angle 0 ◦ and 30 ◦ , helps tuning theoretical models aimed at solving the inverse scattering problem deriving information on the nature of the ejected particles. The Rosetta/OSIRIS camera sampled the coma phase function of comet 67P, with four series acquired at low phase angles from 2015 January to 2016 May. We also added previously published data to our analysis to increase the temporal resolution of our findings. We measured a BSR in the range ∼ [1.7-3.6], broader than the range found in literature from ground-based observations of other comets. We found that during the post-perihelion phase, the BSR is systematically larger than the classical cometary dust values only for nucleocentric distances smaller than ∼ 100 km. We explain this trend in terms of a cloud of chunks orbiting the nucleus at distances < 100 km ejected during perihelion and slowly collapsing on the nucleus over a few months because of the coma gas drag. This also implies that the threshold particle size for the dust phase function to become similar to the nucleus phase function is between 2.5 mm and 0.1 m, taking into account previous Rosetta findings. © 2018 The Author(s)., The support of the national funding agencies of Germany (DLR: Deutschen Zentrums fur Luft-und Raumfahrt), France (CNES: Centre national d' etudes spatiales), Italy (ASI: Agenzia Spaziale Italiana), Spain (MEC: Ministry of Education& Science), Sweden (SNSB: Swedish National Space Board), and the European Space Agency (ESA) Technical Directorate is gratefully acknowledged.
Published: 2019

10. Diurnal variation of dust and gas production in comet 67P/Churyumov-Gerasimenko at the inbound equinox as seen by OSIRIS and VIRTIS-M on board Rosetta

Author: D. Bodewits, Lyn R. Doose, Giovanna Rinaldi, U. Fink, M. De Cecco, Ivano Bertini, Marco Fulle, Maria Teresa Capria, Anny Chantal Levasseur-Regourd, D. Bockelée-Morvan, Imre Toth, Luisa Lara, Sonia Fornasier, H. Krueger, Mauro Ciarniello, Vladimir E. Zakharov, Holger Sierks, Alessandra Migliorini, Gabriele Arnold, Andrea Longobardo, Carsten Güttler, X. Hu, Michelangelo Formisano, Francesco Marzari, Xian Shi, Wing-Huen Ip, Philippe Lamy, F. La Forgia, Stefano Mottola, Gabriele Cremonese, Detlef Koschny, Zhong-Yi Lin, David Kappel, Raphael Marschall, Fredric W. Taylor, V. Da Deppo, S. Ivanovski, J. J. López-Moreno, Fabrizio Capaccioni, Gianrico Filacchione, H. U. Keller, Stéphane Erard, M. C. De Sanctis, Jean-Loup Bertaux, J. Deller, Pedro J. Gutiérrez, Stefano Debei, R. Rodrigo, Jacques Crovisier, Giampiero Naletto, Björn Davidsson, Cecilia Tubiana, M. A. Barucci, Colin Snodgrass, Monica Lazzarin, Ludmilla Kolokolova, Agenzia Spaziale Italiana, German Research Foundation, Centre National de la Recherche Scientifique (France), Ministerio de Economía y Competitividad (España), Government of Sweden, European Space Agency, l'Observatoire de Paris, Science and Technology Facilities Council (UK), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Institute for Astronomy [Edinburgh] (IfA), University of Edinburgh, Institut für Geodäsie und Geoinformationstechnik, Technische Universität Berlin (TU), International Space Science Institute [Bern] (ISSI), INAF - Osservatorio Astronomico di Trieste (OAT), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Universita degli Studi di Padova, DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Physics [Auburn], Auburn University (AU), INAF - Osservatorio Astronomico di Padova (OAPD), CNR Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), Department of Industrial Engineering [Padova], University of Trento [Trento], Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Institut für Physik und Astrophysik [Potsdam], Universität Potsdam, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Universita degli studi di Napoli 'Parthenope' [Napoli], Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Department of Physics [Oxford], University of Oxford [Oxford], Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Technische Universität Berlin (TUB), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), IMPEC - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), NASA-California Institute of Technology (CALTECH), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Technische Universität Braunschweig [Braunschweig], and Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)
Subjects: Asteroiden und Kometen, 67P/Churyumov-Gerasimenko, Brightness, 010504 meteorology & atmospheric sciences, Comet, Comets, Data analysis, General, Individual, Methods, FOS: Physical sciences, Coma (optics), Spatial distribution, Atmospheric sciences, 01 natural sciences, 7. Clean energy, Methods: data analysis, individual: 67P/Churyumov-Gerasimenko [Comets], 0103 physical sciences, data analysis [methods], ddc:530, 010303 astronomy & astrophysics, Southern Hemisphere, Comet: individual: 67P/Churyumov-Gerasimenko, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), [PHYS]Physics [physics], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Diurnal temperature variation, Leitungsbereich PF, comets: individual: 67P/Churyumov-Gerasimenko, Institut für Physik und Astronomie, general [Comets], Astronomy and Astrophysics, Comets: general, 13. Climate action, Space and Planetary Science, astro-ph.EP, Environmental science, Spatial variability, Longitude, Astrophysics - Earth and Planetary Astrophysics
Abstract: Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Open Access funding provided by Max Planck Society., On 27 April 2015, when comet 67P/Churyumov-Gerasimenko was at 1.76 au from the Sun and moving toward perihelion, the OSIRIS and VIRTIS-M instruments on board the Rosetta spacecraft simultaneously observed the evolving dust and gas coma during a complete rotation of the comet.© C. Tubiana et al. 2019, OSIRIS was built by a consortium led by the Max-Planck-Institut fur Sonnensystemforschung, Gottingen, Germany, in collaboration with CISAS, University of Padova, Italy, the Laboratoire d'Astrophysique de Marseille, France, the Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain, the Scientific Support Office of the European Space Agency, Noordwijk, The Netherlands, the Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, the Universidad Politechnica de Madrid, Spain, the Department of Physics and Astronomy of Uppsala University, Sweden, and the Institut fur Daten-technik und Kommunikationsnetze der Technischen Universitat Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. We thank the Rosetta Science Ground Segment at ESAC, the Rosetta Mission Operations Centre at ESOC and the Rosetta Project at ESTEC for their outstanding work enabling the science return of the Rosetta Mission. VIRTIS was built by a consortium, which includes Italy, France, and Germany, under the scientific responsibility of the Istituto di Astrofisica e Planetologia Spaziali of INAF, Italy, which also guides the scientific operations. The VIRTIS instrument development, led by the prime contractor Leonardo-Finmeccanica (Florence, Italy), has been funded and managed by ASI, with contributions from Observatoire de Meudon financed by CNES, and from DLR. We thank the Rosetta Science Ground Segment and the Rosetta Mission Operations Centre for their support throughout all the phases of the mission. The VIRTIS calibrated data will be available through the ESA's Planetary Science Archive Website (www.rssd.esa.int) and is available upon request until posted to the archive. We thank the following institutions and agencies for support of this work: Italian Space Agency (ASI, Italy) contract number I/024/12/1, Centre National d'Etudes Spatiales (CNES, France), DLR (Germany), NASA (USA) Rosetta Program, and Science and Technology Facilities Council (UK).
Published: 2019

11. Quantitative analysis of isolated boulder fields on comet 67P/Churyumov-Gerasimenko

Author: Philippe Lamy, G. Cremonese, W.-H. Ip, Pamela Cambianica, Marco Fulle, Sabrina Ferrari, Dennis Bodewits, Matteo Massironi, Alice Lucchetti, Frank Scholten, Jean-Loup Bertaux, P. J. Gutierrez, F. La Forgia, Björn Davidsson, Francesco Marzari, Carsten Güttler, Z. Y. Lin, Jakob Deller, Cecilia Tubiana, Ivano Bertini, Detlef Koschny, M. De Cecco, Monica Lazzarin, M. A. Barucci, Holger Sierks, Emanuele Simioni, H. U. Keller, S. Fornasier, R. Rodrigo, Stefano Debei, L. M. Lara, V. Da Deppo, Xian Shi, Stefano Mottola, J.-B. Vincent, Giampiero Naletto, Luca Penasa, Maurizio Pajola, Imre Tóth, J. J. Lopez-Moreno, Cambianica, P. [https://orcid.org/0000-0002-8091-4915], European Space Agency (ESA), Centre National D'Etudes Spatiales (CNES), Agencia Estatal de Investigación (AEI), Deutsches Zentrum für Luft- und Raumfahrt (DLR), Agenzia Spaziale Italiana (ASI), Swedish National Space Agency (SNSA), German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Dipartimento di Fisica e Astronomia 'Galileo Galilei', CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), Dipartimento di Geoscienze [Padova], Department of Physics [Auburn], Auburn University (AU), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), European Space Research and Technology Centre (ESTEC), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), IMPEC - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), NASA-California Institute of Technology (CALTECH), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), and Technische Universität Braunschweig [Braunschweig]
Subjects: 67P/Churyumov-Gerasimenko, 010504 meteorology & atmospheric sciences, Comets, Data analysis, General, Individual, Methods, Population, Comet, Narrow angle, Geometry, Astrophysics, 01 natural sciences, Power law, Fractal, individual: 67P/Churyumov-Gerasimenko [Comets], Power index, 0103 physical sciences, education, data analysis [Methods], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, [PHYS]Physics [physics], Physics, Comets: individual: 67P/Churyumov-Gerasimenko, education.field_of_study, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], general [Comets], Astronomy and Astrophysics, methods: data analysis, Comets: general, Space and Planetary Science, Spatial ecology, comets: general – comets: individual: 67P/Churyumov-Gerasimenko – methods: data analysis, Sublimation (phase transition), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: We provide a detailed quantitative analysis of isolated boulder fields situated in three different regions of comet 67P/Churyumov-Gerasimenko: Imhotep, Hapi, and Hatmehit. This is done to supply a useful method for analyzing the morphology of the boulders and to characterize the regions themselves. Methods. We used OSIRIS Narrow Angle Camera images with a spatial scale smaller than 2 mpx(-1) and analyzed the size-frequency distribution and the cumulative fractional area per boulder population. In addition, we correlated shape parameters, such as circularity and solidity, with both the spatial and the size-frequency distribution of the three populations. Results. We identified 11 811 boulders in the Imhotep, Hapi, and Hatmehit regions. We found that the Hatmehit and Imhotep areas show power indices in the range of -2.3/-2.7. These values could represent a transition between gravitational events caused by thermal weathering and sublimation, and material formed during collapses that has undergone sublimation. The Hapi area is characterized by a lower power index (-1.2/-1.7), suggesting that those boulders have a different origin. They can be the result of material formed during gravitational events and collapses that has undergone continuous fragmentation. We calculated the cumulative fractional area (CFA) in order to investigate how the area is covered by boulders as a function of their sizes. The Hatmehit and Imhotep regions show a CFA that is well fit by a power law. In contrast, the Hapi area does not show the same trend. We analyzed the fractal distributions, finding that the populations seem to be fractal at all dimensions, except for the Hapi distribution, which shows a possible fractal behavior for small dimensions only. Finally, the average values of the shape parameters reveal solid and roundish boulders in all populations we studied.© ESO 2019, OSIRIS was built by a consortium of the Max-Planck Institut fur Sonnensystemforschung, in Guttingen, Germany, CISAS University of Padova, Italy, the Laboratoire de Astrophysique de Marseille, France, the Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain, the Research and Scientific Support Department of the European Space Agency, Noordwijk, The Netherlands, the Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, the Universidad Politechnica de Madrid, Spain, the Department of Physics and Astronomy of Uppsala University, Sweden, and the Institut fur Datentechnik und Kommunikationsnetze der Technischen Universitat Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. We thank the ESA teams at ESAC, ESOC and ESTEC for their work in support of the Rosetta mission. We made use of Arcgis 10.3.1 software together with the Matlab, Java, and ImageJ software to perform our analysis. I thank Frederic Moisy for sharing the box-count work.
Published: 2019

12. Rosetta/OSIRIS observations of the 67P nucleus during the April 2016 flyby: High-resolution spectrophotometry

Author: H. U. Keller, Alice Lucchetti, M. De Cecco, Giampiero Naletto, D. Bodewits, Monica Lazzarin, Francesco Marzari, R. Rodrigo, P. J. Gutiérrez, Maurizio Pajola, Sonia Fornasier, J. D. P. Deshapriya, Stefano Debei, F. La Forgia, A. Barucci, J. J. López-Moreno, V. Da Deppo, Frank Preusker, Wing-Huen Ip, Philippe Lamy, Matteo Massironi, C. Feller, Holger Sierks, Pedro Hasselmann, Gabriele Cremonese, Björn Davidsson, Cecilia Tubiana, Luisa Lara, B. Gaskell, Carsten Güttler, Frank Scholten, Ivano Bertini, Marco Fulle, Sabrina Ferrari, Xian Shi, Stefano Mottola, Jean-Loup Bertaux, Detlef Koschny, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Dipartimento di Fisica e Astronomia 'Galileo Galilei', CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Department of Physics [Auburn], Auburn University (AU), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Planetary Science Institute [Tucson] (PSI), Feller, C. [0000-0002-2941-3875], Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737, German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), IMPEC - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), NASA-California Institute of Technology (CALTECH), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), and Technische Universität Braunschweig [Braunschweig]
Subjects: Asteroiden und Kometen, 67P/Churyumov-Gerasimenko, 010504 meteorology & atmospheric sciences, techniques: image processing, Astrophysics, 01 natural sciences, individual: 67P/Churyumov-Gerasimenko [Comets], Frost line, Spectrophotometry, Spectral slope, Methods, Churyumov–Gerasimenko, image processing [Techniques], space vehicles: instruments, data analysis [Methods], 010303 astronomy & astrophysics, Earth and Planetary Astrophysics (astro-ph.EP), Comets: individual: 67P/Churyumov-Gerasimenko, Physics, [PHYS]Physics [physics], biology, medicine.diagnostic_test, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Resolution (electron density), Comets, Data analysis, Image processing, Individual, Instruments, Space vehicles, Techniques, individual: 67P [Comets], Comet, FOS: Physical sciences, Terrain, Context (language use), instruments [Space vehicles], 0103 physical sciences, medicine, 0105 earth and related environmental sciences, Planetengeodäsie, space vehicles – space vehicles: instruments – comets: individual: 67P/Churyumov–Gerasimenko – techniques: image processing – methods: data analysis, Astronomy and Astrophysics, biology.organism_classification, methods: data analysis, 13. Climate action, Space and Planetary Science, Osiris, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Earth and Planetary Astrophysics
Abstract: From August 2014 to September 2016, the Rosetta spacecraft followed comet 67P/Churyumov-Gerasimenko along its orbit. After the comet passed perihelion, Rosetta performed a flyby manoeuvre over the Imhotep-Khepry transition in April 2016. The OSIRIS/Narrow-Angle-Camera (NAC) acquired 112 observations with mainly three broadband filters (centered at 480, 649, and 743 nm) at a resolution of up to 0.53 m/px and for phase angles between 0.095 degrees and 62 degrees. Aims. We have investigated the morphological and spectrophotometrical properties of this area using the OSIRIS/NAC high-resolution observations. Methods. We assembled the observations into coregistered color cubes. Using a 3D shape model, we produced the illumination conditions and georeference for each observation. We mapped the observations of the transition to investigate its geomorphology. Observations were photometrically corrected using the Lommel-Seeliger disk law. Spectrophotometric analyses were performed on the coregistered color cubes. These data were used to estimate the local phase reddening. Results. The Imhotep-Khepry transition hosts numerous and varied types of terrains and features. We observe an association between a feature's nature, its reflectance, and its spectral slopes. Fine material deposits exhibit an average reflectance and spectral slope, while terrains with diamictons, consolidated material, degraded outcrops, or features such as somber boulders present a lower-than-average reflectance and higher-than-average spectral slope. Bright surfaces present here a spectral behavior consistent with terrains enriched in water-ice. We find a phase-reddening slope of 0.064 +/- 0.001%/100 nm/degrees at 2.7 au outbound, similar to the one obtained at 2.3 au inbound during the February 2015 flyby. Conclusions. Identified as the source region of multiple jets and a host of water-ice material, the Imhotep-Khepry transition appeared in April 2016, close to the frost line, to further harbor several potential locations with exposed water-ice material among its numerous different morphological terrain units.© ESO 2019, OSIRIS was built by a consortium of the Max-Planck-Institut fur Sonnensystemforschung, Gottingen, Germany, CISAS-University of Padova, Italy, Laboratoire d'Astrophysique de Marseille, France, Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain, Research and Scientific Support Department of the European Space Agency, Noordwijk, The Netherlands, Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, Universidad Politechnica de Madrid, Spain, Department of Physics and Astronomy of Uppsala University, Sweden, and Institut fur Datentechnik und Kommunikationsnetze der Technischen Universitat Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae lander is provided by a consortium led by DLR, MPS, CNES, and ASI. The SPICE libraries and PDS resources are developed and maintained by NASA. The authors thank the referee and editors for their questions, remarks, and advices for the improvement of this article.
Published: 2019

13. Experimental phase function and degree of linear polarization of cometary dust analogues

Author: F. La Forgia, Alberto Cellino, Monica Lazzarin, E. Frattin, Gabriele Cremonese, François Raulin, Patrice Coll, Jesús Escobar-Cerezo, F. Moreno, Giampiero Naletto, Ivano Bertini, Olga Muñoz, J. Nava, J. C. Gómez Martín, D. Guirado, University of Helsinki, Department of Physics, ITA, ESP, Ministerio de Economía y Competitividad (España), and Department of Physics
Subjects: STARDUST, THOLINS, FOS: Physical sciences, Astrophysics, 01 natural sciences, T-MATRIX, Scattering, cometary dust analogues, phase function, linear polarization, PARTICULATE SURFACES, phase function, CV3 CHONDRITES, 0103 physical sciences, Phase function, PARTICLES, 010303 astronomy & astrophysics, Physics, Earth and Planetary Astrophysics (astro-ph.EP), T matrix, Degree (graph theory), 010308 nuclear & particles physics, Linear polarization, MINERALOGY, Astronomy and Astrophysics, cometary dust analogues, REFLECTANCE SPECTRA, 115 Astronomy, Space science, LIGHT-SCATTERING, 3. Good health, 13. Climate action, Space and Planetary Science, Physics::Space Physics, 81P/WILD-2, Astrophysics::Earth and Planetary Astrophysics, linear polarization, Astrophysics - Earth and Planetary Astrophysics
Abstract: We present experimental phase function and degree of linear polarization curves for seven samples of cometary dust analogues namely: ground pieces of Allende, DaG521, FRO95002, and FRO99040 meteorites, Mg-rich olivine and pyroxene, and a sample of organic tholins. The experimental curves have been obtained at the IAA Cosmic Dust Laboratory at a wavelength of 520 nm covering a phase angle range from 3 ◦ to 175 ◦ . We also provide values of the backscattering enhancement for our cometary analogue samples. The final goal of this work is to compare our experimental curves with observational data of comets and asteroids to better constrain the nature of cometary and asteroidal dust grains. All measured phase functions present the typical behaviour for μm-sized cosmic dust grains. Direct comparison with data provided by the OSIRIS/Rosetta camera for comet 67P/Churyumov-Gerasimenko reveals significant differences and supports the idea of a coma dominated by big chunks, larger than one micrometer. The polarization curves are qualitatively similar to ground-based observations of comets and asteroids. The position of the inversion polarization angle seems to be dependent on the composition of the grains. We find opposite dependence of the maximum of the polarization curve for grains sizes in the Rayleigh-resonance and geometric optics domains, respectively. © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society., This work has been supported by the Plan Nacional de Astronomia y Astrofisica contract AYA2015-67152-R.
Published: 2019

14. Linking surface morphology, composition, and activity on the nucleus of 67P/Churyumov-Gerasimenko

Author: Jessica Agarwal, J. Deller, Pedro J. Gutiérrez, R. Rodrigo, Monica Lazzarin, Gabriele Cremonese, Holger Sierks, J. D. P. Deshapriya, Stefano Debei, D. Bodewits, Björn Davidsson, Cecilia Tubiana, Imre Toth, Pedro Hasselmann, Giampiero Naletto, Marco Fulle, Sabrina Ferrari, M. A. Barucci, Sonia Fornasier, Carsten Güttler, J. J. Lopez Moreno, Wing-Huen Ip, Philippe Lamy, Cesare Barbieri, Jean-Loup Bertaux, M. De Cecco, F. La Forgia, M. Küppers, Z. Y. Lin, Maurizio Pajola, M. L. Lara, Ivano Bertini, H. U. Keller, V. Da Deppo, Francesco Marzari, C. Feller, Van H. Hoang, Detlef Koschny, Xian Shi, Stefano Mottola, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institute of Physics [Hanoi], Vietnam Academy of Science and Technology (VAST), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, Dipartimento di Fisica e Astronomia 'Galileo Galilei', CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), Department of Mechanical Engineering [Padova], Department of Industrial Engineering [Padova], Universita degli Studi di Padova-Universita degli Studi di Padova, University of Trento [Trento], Dipartimento di Geoscienze [Padova], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Institute of Astronomy [Taiwan] (IANCU), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], European Space Astronomy Centre (ESAC), European Space Agency (ESA), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), IMPEC - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), NASA-California Institute of Technology (CALTECH), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Technische Universität Braunschweig [Braunschweig], ITA, USA, GBR, FRA, DEU, Federal Ministry of Education and Research (Germany), Agence Nationale de la Recherche (France), Agenzia Spaziale Italiana, Ministerio de Ciencia, Innovación y Universidades (España), and Government of Sweden
Subjects: Asteroiden und Kometen, 67P/Churyumov-Gerasimenko, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Comet, observational [methods], Data analysis, FOS: Physical sciences, Coma (optics), Individual, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Photometric, 01 natural sciences, photometric [techniques], techniques: photometric, individual: 67P/Churyumov-Gerasimenko [Comets], Comet nucleus, 0103 physical sciences, medicine, data analysis [methods], Comets, Methods, 010303 astronomy & astrophysics, Observational, Optical depth, 0105 earth and related environmental sciences, Physics, Comets: individual: 67P/Churyumov-Gerasimenko, Earth and Planetary Astrophysics (astro-ph.EP), [PHYS]Physics [physics], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Techniques, Resolution (electron density), Astronomy and Astrophysics, methods: data analysis, Plume, medicine.anatomical_structure, 13. Climate action, Space and Planetary Science, comets: individual: 67P/Churyumov-Gerasimenko – methods: data analysis – methods: observational – techniques: photometric, Radiance, Astrophysics::Earth and Planetary Astrophysics, methods: observational, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Nucleus, Astrophysics - Earth and Planetary Astrophysics
Abstract: Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., The Rosetta space probe accompanied comet 67P/Churyumov-Gerasimenko for more than two years, obtaining an unprecedented amount of unique data of the comet nucleus and inner coma. This has enabled us to study its activity almost continuously from 4 au inbound to 3.6 au outbound, including the perihelion passage at 1.24 au. This work focuses identifying the source regions of faint jets and outbursts and on studying the spectrophotometric properties of some outbursts. We use observations acquired with the OSIRIS/NAC camera during July-October 2015, that is, close to perihelion. Methods. We analyzed more than 2000 images from NAC color sequences acquired with 7-11 filters covering the 250-1000 nm wavelength range. The OSIRIS images were processed with the OSIRIS standard pipeline up to level 3, that is, converted in radiance factor, then corrected for the illumination conditions. For each color sequence, color cubes were produced by stacking registered and illumination-corrected images. Results. More than 200 jets of different intensities were identified directly on the nucleus. Some of the more intense outbursts appear spectrally bluer than the comet dark terrain in the visible-to-near-infrared region. We attribute this spectral behavior to icy grains mixed with the ejected dust. Some of the jets have an extremely short lifetime. They appear on the cometary surface during the color sequence observations, and vanish in less than some few minutes after reaching their peak. We also report a resolved dust plume observed in May 2016 at a resolution of 55 cm pixel(-1), which allowed us to estimate an optical depth of similar to 0.65 and an ejected mass of similar to 2200 kg, assuming a grain bulk density of similar to 800 kg m(-3). We present the results on the location, duration, and colors of active sources on the nucleus of 67P from the medium-resolution (i.e., 6-10 m pixel(-1)) images acquired close to perihelion passage. The observed jets are mainly located close to boundaries between different morphological regions. Some of these active areas were observed and investigated at higher resolution (up to a few decimeter per pixel) during the last months of operations of the Rosetta mission. Conclusions. These observations allow us to investigate the link between morphology, composition, and activity of cometary nuclei. Jets depart not only from cliffs, but also from smooth and dust-covered areas, from fractures, pits, or cavities that cast shadows and favor the recondensation of volatiles. This study shows that faint jets or outbursts continuously contribute to the cometary activity close to perihelion passage, and that these events are triggered by illumination conditions. Faint jets or outbursts are not associated with a particular terrain type or morphology.© S. Fornasier et al. 2019, OSIRIS was built by a consortium led by the Max-Planck-Institut fur Sonnensystemforschung, Goettingen, Germany, in collaboration with CISAS, University of Padova, Italy, the Laboratoire d'Astrophysique de Marseille, France, the Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain, the Scientific Support Office of the European Space Agency, Noordwijk, the Netherlands, the Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, the Universidad Politechnica de Madrid, Spain, the Department of Physics and Astronomy of Uppsala University, Sweden, and the Institut fur Datentechnik und Kommunikationsnetze der Technischen Universitat Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. We thank the Rosetta Science Ground Segment at ESAC, the Rosetta Mission Operations Centre at ESOC and the Rosetta Project at ESTEC for their outstanding work enabling the science return of the Rosetta Mission. S.F. acknowledges the financial support from the France Agence Nationale de la Recherche (programme Classy, ANR-17-CE31-0004). The authors thank H. Campins for his comments that helped us improve this article. The authors would like to thank Andrew Cooper and Marco Parigi for spotting the inconsistencies in regional boundaried of Fig. 1 in the online preprint version of the paper.
Published: 2019

15. Erratum: Characterization of V-type asteroids orbiting in the middle and outer main belt

Author: Alessandra Migliorini, M C De Sanctis, T A Michtchenko, D Lazzaro, M Barbieri, D Mesa, M Lazzarin, and F La Forgia
Subjects: Space and Planetary Science, Astronomy and Astrophysics
Published: 2021

16. The big lobe of 67P/Churyumov–Gerasimenko comet: morphological and spectrophotometric evidences of layering as from OSIRIS data

Author: P. J. Gutierrez, Xian Shi, Carsten Güttler, Pedro Hasselmann, J. J. López-Moreno, Matteo Massironi, Monica Lazzarin, Detlef Koschny, Stubbe F. Hviid, M. A. Barucci, Björn Davidsson, Cecilia Tubiana, Ivano Bertini, Pamela Cambianica, Nicolas Thomas, Michael Küppers, Francesca Ferri, Luca Penasa, Francesco Marzari, M. De Cecco, W-H. Ip, J. L. Bertaux, Marco Franceschi, Laurent Jorda, Holger Sierks, J.-B. Vincent, Olivier Groussin, E. Frattin, F. La Forgia, Stefano Debei, Philippe Lamy, Jakob Deller, Maurizio Pajola, Nilda Oklay, Giampiero Naletto, Ekkehard Kührt, Sonia Fornasier, L. M. Lara, V. Da Deppo, Marco Fulle, Jörg Knollenberg, Emanuele Simioni, Sabrina Ferrari, R. Rodrigo, Gabriele Cremonese, Alice Lucchetti, H. U. Keller, Dennis Bodewits, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, Dipartimento di Fisica e Astronomia 'Galileo Galilei', CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Fundacion Galileo Galilei, Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, CNR Institute for Photonics and Nanotechnologies (IFN), Department of Industrial Engineering [Padova], Dipartimento di Geoscienze [Padova], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Operations Department (ESAC), European Space Astronomy Centre (ESAC), Physikalisches Institut [Bern], Universität Bern [Bern], Center for Space and Habitability (CSH), University of Bern, German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Ferrari, Sabrina, Penasa, L., La Forgia, F., Massironi, M., Naletto, G., Lazzarin, M., Fornasier, S., Hasselmann, P. H., Lucchetti, A., Pajola, M., Ferri, F., Cambianica, Pamela, Oklay, N., Tubiana, C., Sierks, H., Lamy, P. L., Rodrigo, R., Koschny, D., Davidsson, B., Barucci, M. A., Bertaux, J. -L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Deller, J., Franceschi, M., Frattin, Elisa, Fulle, M., Groussin, O., Gutiérrez, P. J., Güttler, C., Hviid, S. F., Ip, W. -H., Jorda, L., Keller, H. U., Knollenberg, J., Kührt, E., Küppers, M., Lara, L. M., López-Moreno, J. J., Marzari, F., Shi, X., Simioni, E., Thomas, N., Vincent, J. -B., Università degli Studi di Padova = University of Padua (Unipd), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), NASA-California Institute of Technology (CALTECH), Universität Bern [Bern] (UNIBE), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), IMPEC - LATMOS, Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), and Technische Universität Braunschweig [Braunschweig]
Subjects: 67P/Churyumov-Gerasimenko, Brightness, Comets: general, Comets: individual: 67P/Churyumov-Gerasimenko, Methods: data analysis, Techniques: image processing, Astronomy and Astrophysics, Space and Planetary Science, 010504 meteorology & atmospheric sciences, Multispectral image, Comet, Data analysis, Mineralogy, Spatial distribution, 01 natural sciences, Texture (geology), Image processing, individual: 67P/Churyumov-Gerasimenko [Comets], 0103 physical sciences, medicine, Comets, image processing [Techniques], spectral variegation, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [PHYS]Physics [physics], biology, OSIRIS cameras, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 520 Astronomy, general [Comets], Astronomy and Astrophysic, biology.organism_classification, 620 Engineering, Lobe, data analysi [Methods], medicine.anatomical_structure, multiple-filters, Variegation (histology), Osiris
Abstract: Between 2014 and 2016, ESA's Rosetta OSIRIS cameras acquired multiple-filters images of the layered nucleus of comet 67P/Churyumov-Gerasimenko, ranging from ultraviolet to near-infrared wavelengths. No correlation between layers disposition and surface spectral variegation has been observed so far. This paper investigates possible spectral differences among decametre-thickness outcropping layers of the biggest lobe of the comet by means of OSIRIS image dataset. A two-classes maximum likelihood classification was applied on consolidated outcrops and relative deposits identified on post-perihelion multispectral images of the big lobe. We distinguished multispectral data on the basis of the structural elevation of the onion-shell Ellipsoidal Model of 67P. The spatial distribution of the two classes displays a clear dependence on the structural elevation, with the innermost class resulting over 50 per cent brighter than the outermost one. Consolidated cometarymaterials located at different structural levels are characterized by different brightness and revealed due to the selective removal of large volumes. This variegation can be attributed to a different texture of the outcrop surface and/or to a different content of refractory materials.© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society., We are grateful to Paul Helfenstein for corrections that improved our paper. OSIRIS was built by a consortium of the Max-Planck-Institut fur Sonnensystemforschung, in Goottingen, Germany, CISAS-University of Padova, Italy, the Laboratoire d'Astrophysique de Marseille, France, the Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain, the Research and Scientific Support Department of the European Space Agency, Noordwijk, The Netherlands, the Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, the Universidad Politechnica de Madrid, Spain, the Department of Physics and Astronomy of Uppsala University, Sweden, and the Institut fur Datentechnik und Kommunikationsnetze der Technischen Universitat Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), Italy (ASI), France (CNES), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. We thank the ESA teams at ESAC, ESOC, and ESTEC for their work in support of the Rosetta mission.
Published: 2018

17. The phase function and density of the dust observed at comet 67P/Churyumov-Gerasimenko

Author: P. J. Gutierrez, W-H. Ip, F. Moreno, Monica Lazzarin, F. La Forgia, Ivano Bertini, Xian Shi, V. Da Deppo, Cesare Barbieri, Stefano Mottola, Holger Sierks, Giampiero Naletto, Pasquale Palumbo, M. A. Barucci, Jakob Deller, Stavro Ivanovski, H. S. Hviid, J. Lasue, Giovanna Rinaldi, Marco Fulle, Michael Küppers, Philippe Lamy, Hans Rickman, Stefano Debei, Ekkehard Kührt, Alessandra Rotundi, Detlef Koschny, Nicolas Thomas, R. Rodrigo, M. De Cecco, J.-R. Kramm, Björn Davidsson, Cecilia Tubiana, Laurent Jorda, G. Cremonese, Carsten Güttler, J. L. Bertaux, Anny Chantal Levasseur-Regourd, M. L. Lara, Olivier Groussin, Sonia Fornasier, Jörg Knollenberg, V. Della Corte, J. J. López-Moreno, H. U. Keller, Francesco Marzari, Dennis Bodewits, Agenzia Spaziale Italiana, INAF - Osservatorio Astronomico di Trieste (OAT), Istituto Nazionale di Astrofisica (INAF), Helmholtz zentrum für Schwerionenforschung GmbH (GSI), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Universita degli Studi di Padova, Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Dipartimento di Scienze e Tecnologie [Napoli] (DIST), Universita degli studi di Napoli 'Parthenope' [Napoli], Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Department of Physics and Astronomy [Uppsala], Uppsala University, Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, INAF - Osservatorio Astronomico di Padova (OAPD), Laboratory for Ultraviolet and X-ray Optical Research [Padova] (LUXOR), CNR Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR)-Consiglio Nazionale delle Ricerche [Roma] (CNR), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Department of Industrial Engineering [Padova], University of Trento [Trento], Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], European Space Astronomy Centre (ESAC), Physikalisches Institut [Bern], Universität Bern [Bern], Università degli Studi di Padova = University of Padua (Unipd), Università degli Studi di Napoli 'Parthenope' = University of Naples (PARTHENOPE), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Agence Spatiale Européenne = European Space Agency (ESA), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)-National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), NASA-California Institute of Technology (CALTECH), Universität Bern [Bern] (UNIBE), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), IMPEC - LATMOS, Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Polska Akademia Nauk (PAN), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Technische Universität Braunschweig [Braunschweig], INAF - Osservatorio Astronomico di Trieste ( OAT ), Istituto Nazionale di Astrofisica ( INAF ), Istituto di Astrofisica e Planetologia Spaziali ( IAPS ), Dipartimento di Scienze e Tecnologie [Napoli] ( DIST ), Max-Planck-Institut für Sonnensystemforschung ( MPS ), Institut de recherche en astrophysique et planétologie ( IRAP ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Atmosphères, Milieux, Observations Spatiales ( LATMOS ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Instituto de Astrofísica de Andalucía ( IAA ), Consejo Superior de Investigaciones Científicas [Spain] ( CSIC ), Deutsches Zentrum für Luft- und Raumfahrt [Berlin] ( DLR ), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' ( CISAS ), Laboratoire d'Astrophysique de Marseille ( LAM ), Aix Marseille Université ( AMU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National d'Etudes Spatiales ( CNES ) -Centre National de la Recherche Scientifique ( CNRS ), Centro de Astrobiologia [Madrid] ( CAB ), Instituto Nacional de Técnica Aeroespacial ( INTA ) -Consejo Superior de Investigaciones Científicas [Spain] ( CSIC ), International Space Science Institute ( ISSI ), European Space Research and Technology Centre ( ESTEC ), European Space Agency ( ESA ), Space Research Centre [Warsaw] ( CBK ), Polska Akademia Nauk ( PAN ), Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), INAF - Osservatorio Astronomico di Padova ( OAPD ), Laboratory for Ultraviolet and X-ray Optical Research [Padova] ( LUXOR ), CNR Institute for Photonics and Nanotechnologies ( IFN ), Consiglio Nazionale delle Ricerche [Roma] ( CNR ) -Consiglio Nazionale delle Ricerche [Roma] ( CNR ), Jet Propulsion Laboratory ( JPL ), NASA-California Institute of Technology ( CALTECH ), National Central University [Taiwan] ( NCU ), Space Science Institute [Macau] ( SSI ), Macau University of Science and Technology ( MUST ), Aix Marseille Université ( AMU ), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] ( IGEP ), and European Space Astronomy Center ( ESAC )
Subjects: 67P/Churyumov-Gerasimenko, Brightness, comets: individual: 67P/Churyumov- Gerasimenko, 010504 meteorology & atmospheric sciences, Comet, Dust particles, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, space vehicles, comets: general, comets: individual: 67P/Churyumov-Gerasimenko, 01 natural sciences, Astronomi, astrofysik och kosmologi, individual: 67P/Churyumov-Gerasimenko [Comets], 0103 physical sciences, Astronomy, Astrophysics and Cosmology, Phase function, Astrophysics::Solar and Stellar Astrophysics, comets, Particle density, 010303 astronomy & astrophysics, [ SDU.ASTR ] Sciences of the Universe [physics]/Astrophysics [astro-ph], Astrophysics::Galaxy Astrophysics, Comets: individual: 67P/Churyumov, Gerasimenko, 0105 earth and related environmental sciences, Physics, 520 Astronomy, comets: general, comets: individual: 67P/Churyumov-Gerasimenko, general [Comets], Astronomy and Astrophysics, Space vehicles, 620 Engineering, Bulk density, space vehicles, comets: general, comets: individual: 67P/Churyumov- Gerasimenko, Density distribution, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], space vehicles, Astrophysics::Earth and Planetary Astrophysics, Mass fraction
Abstract: The OSIRIS camera onboard Rosetta measured the phase function of both the coma dust and the nucleus. The two functions have a very different slope versus the phase angle. Here, we show that the nucleus phase function should be adopted to convert the brightness to the size of dust particles larger than 2.5 mm only. This makes the dust bursts observed close to Rosetta by OSIRIS, occurring about every hour, consistent with the fragmentation on impact with Rosetta of parent particles, whose flux agrees with the dust flux observed by GIADA. OSIRIS also measured the antisunward acceleration of the fragments, thus providing the first direct measurement of the solar radiation force acting on the dust fragments and thus of their bulk density, excluding any measurable rocket effect by the ice sublimation from the dust. The obtained particle density distribution has a peak matching the bulk density of most COSIMA particles, and represents a subset of the density distribution measured by GIADA. This implies a bias in the elemental abundances measured by COSIMA, which thus are consistent with the 67P dust mass fractions inferred by GIADA, i.e. (38 ± 8) per cent of hydrocarbons versus the (62 ± 8) per cent of sulphides and silicates.© 2018 The Author(s).Published by Oxford University Press on behalf of the Royal Astronomical Society., We thank the anonymous referee for having significantly improved the paper; and the Rosetta Science Ground Segment at ESAC, the Rosetta Mission Operations Centre at ESOC, and the Rosetta Project at ESTEC for their outstanding work enabling the science return of the Rosetta Mission. All GIADA data presented here are available on request before archiving in the PSA. This research was supported by the Italian Space Agency (ASI) within the ASI-INAF agreements I/032/05/0 and I/024/12/0.
Published: 2018

18. Spectroscopic observations of the bilobate potentially hazardous asteroid 2014 JO25 from the Asiago 1.22-m telescope

Author: Monica Lazzarin, Francesca Ferri, F. La Forgia, Giampiero Naletto, Alessandro Siviero, V. Petropoulou, P. Ochner, and Ivano Bertini
Subjects: Rotation period, Potentially hazardous object, Astronomy, Astronomy and Astrophysics, 010502 geochemistry & geophysics, Stellar classification, 01 natural sciences, Spectral line, law.invention, Radar observations, Telescope, law, Asteroid, Space and Planetary Science, 0103 physical sciences, 010303 astronomy & astrophysics, Spectrograph, Geology, 0105 earth and related environmental sciences
Abstract: The potentially hazardous asteroid (PHA) 2014 JO25 made a close approach to Earth on 19 April 2017 at the distance of 0.0118 AU, giving the opportunity to study its nature with large spatial resolution from ground-based observatories. Radar observations revealed an object with a clear bilobate shape. We aimed at the characterization of the surface properties of the object, the determination of its spectral class and the search for possible surface heterogeneities, possibly linked to the two lobes, during different rotational phases. Fourteen low-resolution spectra were acquired with the Boller & Chivens optical spectrograph mounted on the 1.22–m Asiago telescope. The spectra covered an entire rotation period of the asteroid. Data were reduced using IRAF and analyzed with the M4AST tool to infer the best fit Bus-Demeo taxonomy type. We found the asteroid belonging to the S/Q complex of silicaceous asteroids, complex comprising the vast majority of NEAs. This is the tenth bilobate NEA to be taxonomically classified and only the seventh bilobate PHA. We found no clear proof of surface heterogeneity, but there is an interestingvariation in the best spectral match which appears to be synchronous with the rotation period of the object.
Published: 2018

19. A three-dimensional modelling of the layered structure of comet 67P/Churyumov-Gerasimenko

Author: Hans Rickman, Matteo Massironi, J.-R. Kramm, Ivano Bertini, Stubbe F. Hviid, Francesco Marzari, P. J. Gutierrez, M. De Cecco, Emanuele Simioni, Ekkehard Kührt, L. M. Lara, Frank Scholten, Detlef Koschny, Cesare Barbieri, Maurizio Pajola, R. Rodrigo, V. Da Deppo, Jakob Deller, Frank Preusker, S. Fornasier, Monica Lazzarin, Jean-Baptiste Vincent, Giampiero Naletto, Francesca Ferri, Robert Gaskell, Jessica Agarwal, Wing-Huen Ip, J-C. Lee, Laurent Jorda, N. Thomas, M. A. Barucci, Björn Davidsson, Michael Küppers, Alice Lucchetti, M. F. A'Hearn, Clement Feller, Marc Hofmann, Cecilia Tubiana, Olivier Groussin, Stefano Debei, Gabriele Cremonese, Holger Sierks, Marco Fulle, Philippe Lamy, Sabrina Ferrari, J. J. Lopez Moreno, F. La Forgia, Nilda Oklay, Carsten Güttler, E. Frattin, Luca Penasa, J. L. Bertaux, H. U. Keller, Jörg Knollenberg, Xian Shi, Stefano Mottola, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), Dipartimento di Astronomia [Padova], INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), NASA Ames Research Center (ARC), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Planetary Science Institute [Tucson] (PSI), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Department of Physics and Astronomy [Uppsala], Uppsala University, Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Mechanical Engineering [Padova], Department of Industrial Engineering [Padova], Università degli Studi di Padova = University of Padua (Unipd)-Università degli Studi di Padova = University of Padua (Unipd), Università degli Studi di Trento (UNITN), INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Department of Earth Sciences [Chung-Li City], National Central University [Taiwan] (NCU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), DLR Institute of Planetary Research, German Aerospace Center (DLR), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Universita degli Studi di Padova, Consiglio Nazionale delle Ricerche [Roma] (CNR), California Institute of Technology (CALTECH)-NASA, Max-Planck-Institut für Sonnensystemforschung (MPS), European Space Agency (ESA), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Universita degli Studi di Padova-Universita degli Studi di Padova, European Space Agency (ESA)-European Space Agency (ESA), and Universität Bern [Bern]
Subjects: 010504 meteorology & atmospheric sciences, Geometry, Concentric, Classification of discontinuities, 01 natural sciences, Layered structure, 0103 physical sciences, medicine, 010303 astronomy & astrophysics, Comets: individual: 67P/Churyumov, Gerasimenko, 0105 earth and related environmental sciences, Comets: general, Methods: data analysis, Physics, [PHYS]Physics [physics], comets: individual: 67P/Churyumov–Gerasimenko, comets: general, Astronomy and Astrophysics, Dimensional modeling, Ellipsoid, methods: data analysis, Lobe, medicine.anatomical_structure, Space and Planetary Science, Layering, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Free parameter
Abstract: International audience; We provide a three-dimensional model of the inner layered structure of comet 67P based on the hypothesis of an extended layering independently wrapping each lobe. A large set of terrace orientations was collected on the latest shape model and then used as a proxy for the local orientation of the surfaces of discontinuity which defines the layers. We modelled the terraces as a family of concentric ellipsoidal shells with fixed axis ratios, producing a model that is completely defined by just eight free parameters. Each lobe of 67P has been modelled independently, and the two sets of parameters have been estimated by means of non-linear optimization of the measured terrace orientations. The proposed model is able to predict the orientation of terraces, the elongation of cliffs, the linear traces observed in the Wosret and Hathor regions and the peculiar alignment of boulder-like features which has been observed in the Hapi region, which appears to be related to the inner layering of the big lobe. Our analysis allowed us to identify a plane of junction between the two lobes, further confirming the independent nature of the lobes. Our layering models differ from the best-fitting topographic ellipsoids of the surface, demonstrating that the terraces are aligned to an internal structure of discontinuities, which is unevenly exposed on the surface, suggesting a complex history of localized material removal from the nucleus.
Published: 2017

20. Post-perihelion photometry of dust grains in the coma of 67P Churyumov-Gerasimenko

Author: Carsten Güttler, Xian Shi, Ekkehard Kührt, L. M. Lara, Alice Lucchetti, Cesare Barbieri, J. B. Vincent, Stefano Mottola, P. Lamy, Hans Rickman, P. J. Gutierrez, Theresa Ott, Jakob Deller, Matteo Massironi, Jörg Knollenberg, Luca Penasa, Stubbe F. Hviid, Holger Sierks, Michael Küppers, F. La Forgia, J.-R. Kramm, J. L. Bertaux, Nilda Oklay, Ivano Bertini, Gabriele Cremonese, Wing-Huen Ip, Laurent Jorda, M. A. Barucci, Monica Lazzarin, J. J. Lopez Moreno, M. F. A'Hearn, Stefano Debei, Olivier Groussin, E. Frattin, V. Da Deppo, Emanuele Simioni, B. J. R. Davidsson, Horst Uwe Keller, Marc Hofmann, R. Rodrigo, Maurizio Pajola, A. Gicquel, Cecilia Tubiana, Sonia Fornasier, M. De Cecco, Giampiero Naletto, Francesco Marzari, Francesca Ferri, Jessica Agarwal, Marco Fulle, Detlef Koschny, Esther Drolshagen, Sabrina Ferrari, Nicolas Thomas, ITA, USA, GBR, FRA, DEU, INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Università degli Studi di Padova = University of Padua (Unipd), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), University of Oldenburg, Carl Von Ossietzky Universität Oldenburg = Carl von Ossietzky University of Oldenburg (OFFIS), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Physics and Astronomy [Uppsala], Uppsala University, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Industrial Engineering [Padova], University of Trento [Trento], Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), European Space Astronomy Centre (ESAC), Dipartimento di Geoscienze [Padova], Department of Information Engineering [Padova] (DEI), NASA Ames Research Center (ARC), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Universita degli Studi di Padova, Consiglio Nazionale delle Ricerche [Roma] (CNR), Carl Von Ossietzky Universität Oldenburg, Max-Planck-Institut für Sonnensystemforschung (MPS), European Space Agency (ESA), Universität Bern [Bern], Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)
Subjects: Asteroiden und Kometen, 010504 meteorology & atmospheric sciences, Comet, Data analysis, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics, 01 natural sciences, Spectral line, Photometry (optics), Photometry, Methods: data analysis, 0103 physical sciences, Spectral slope, Rosetta, Comets, OSIRIS, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [PHYS]Physics [physics], [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 520 Astronomy, Zodiacal dust, Astronomy and Astrophysics, 620 Engineering, Comets: general, Wavelength, Techniques: photometric, Space and Planetary Science, Water ice, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Automated method
Abstract: International audience; We present a photometric analysis of individual dust grains in the coma of comet 67P/Churyumov–Gerasimenko using OSIRIS images taken from 2015 July to 2016 January. We analysed a sample of 555 taken during 18 d at heliocentric distances ranging between 1.25 and 2.04 au and at nucleocentric distances between 80 and 437 km. An automated method to detect the tracks was specifically developed. The images were taken by OSIRIS NAC in four different filters: Near-IR (882 nm), Orange (649 nm), FarOrange (649 nm) and Blue (480 nm). It was not always possible to recognize all the grains in the four filters, hence we measured the spectral slope in two wavelengths ranges: in the interval [480–649] nm, for 1179 grains, and in the interval [649–882] nm, for 746 grains. We studied the evolution of the two populations’ average spectral slopes. The data result scattered around the average value in the range [480–649] nm, while in the [649–882] nm we observe a slight decreasing moving away from the Sun as well as a slight increasing with the nucleocentric distance. A spectrophotometric analysis was performed on a subsample of 339 grains. Three major groups were defined, based on the spectral slope between [535–882] nm: (i) the steep spectra that may be related with organic material, (ii) the spectra with an intermediate slope, likely a mixture of silicates and organics and (iii) flat spectra that may be associated with a high abundance of water ice.
Published: 2017

21. Geomorphological and spectrophotometric analysis of Seth's circular niches on comet 67P/Churyumov–Gerasimenko using OSIRIS images

Author: Monica Lazzarin, M. F. A'Hearn, Björn Davidsson, Cecilia Tubiana, Marco Fulle, Olivier Groussin, Frank Scholten, J.-B. Vincent, Sabrina Ferrari, Ekkehard Kührt, Xian Shi, Horst Uwe Keller, Stefano Mottola, L. M. Lara, Ivano Bertini, Michael Küppers, P. J. Gutierrez, Steve Boudreault, R. Rodrigo, Alice Lucchetti, Carsten Güttler, L. Z. Lin, F. La Forgia, Cesare Barbieri, Nilda Oklay, Jakob Deller, Holger Sierks, Sonia Fornasier, Detlef Koschny, Nicolas Thomas, V. Da Deppo, Maurizio Pajola, Clement Feller, Wing-Huen Ip, Laurent Jorda, M. Hoffman, Giampiero Naletto, Pedro Hasselmann, Jörg Knollenberg, J.-R. Kramm, Luca Penasa, G. Cremonese, Stefano Debei, M. De Cecco, J. L. Bertaux, J. J. Lopez Moreno, Philippe Lamy, M. A. Barucci, Matteo Massironi, Stubbe F. Hviid, Jessica Agarwal, Francesco Marzari, Hans Rickman, Frank Preusker, INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), NASA Ames Research Center (ARC), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Geoscienze [Padova], CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Information Engineering [Padova] (DEI), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Dipartimento di Fisica e Astronomia 'Galileo Galilei', International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Physics and Astronomy [Uppsala], Uppsala University, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), European Space Astronomy Centre (ESAC), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Universita degli Studi di Padova, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Consiglio Nazionale delle Ricerche [Roma] (CNR), Max-Planck-Institut für Sonnensystemforschung (MPS), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), European Space Agency (ESA), Universität Bern [Bern], and California Institute of Technology (CALTECH)-NASA
Subjects: 010504 meteorology & atmospheric sciences, comets: general-comets, Comet, Data analysis, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Terrain, 67P/Churyumov–Gerasimenko, 01 natural sciences, individual: 67P/Churyumov-Gerasimenko-methods:data analysis, Methods: data analysis, 0103 physical sciences, Size frequency, Cliff, 010303 astronomy & astrophysics, Geomorphology, 0105 earth and related environmental sciences, Remote sensing, Comets: individual: 67P/Churyumov, Gerasimenko, Physics, Ecological niche, Comets: general, geography, geography.geographical_feature_category, biology, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 520 Astronomy, Astronomy and Astrophysics, Landslide, biology.organism_classification, 620 Engineering, 13. Climate action, Space and Planetary Science, Water ice, Osiris
Abstract: International audience; We provide a detailed geomorphological and spectrophotometric analysis of the circular niches located on the Seth region of 67P using OSIRIS images. The features can be related to landslide events that occurred on 67P and shaped its surface, as the recent Aswan cliff collapse detected in the same region. We therefore provide an analysis of the area pre- and post-perihelion suggesting that no specific changes have been observed. To assess this, after performing a geomorphological map of the area that allows us to identify different terrain units, we computed the boulders cumulative size frequency distribution (SFD) of the niches, before and after the perihelion passage. The niches SFDs are characterized by a similar trend with two different power-law indices within the same deposit: lower power-law value (between −2.3 and −2.7) for boulders smaller than 5 m and steeper power-law value (between −4.7 and −5.0) for boulders larger than 5 m. These trends suggest that smaller boulders have evolved and progressively have been depleted (lower power-law index), while bigger boulders are more representative of the event that generated the deposit and are less degraded. Then, we perform the spectrophotometric analysis of this region comparing pre- and post-perihelion results. We found colour changes within the area, in particular brighter patches related to the presence of exposed water ice mixed to the refractory materials have been detected in the post-perihelion images.
Published: 2017

22. Thermophysics of fractures on comet 67P/Churyumov-Gerasimenko

Author: H. U. Keller, D. Bodewits, Xian Shi, R. Moissl-Fraund, Monica Lazzarin, A.-T. Auger, Giampiero Naletto, M. A. Barucci, Jean-Loup Bertaux, Jean-Baptiste Vincent, Harald Michalik, Stefano Mottola, F. Moreno, F. La Forgia, Philippe Lamy, Jürgen Blum, Imre Toth, F. Preusker, Stubbe F. Hviid, Nilda Oklay, X. Hu, Gabriele Cremonese, Sonia Fornasier, M. De Cecco, P. Gutierrez-Marques, Holger Sierks, Wing-Huen Ip, Laurent Jorda, Marco Fulle, Ekkehard Kührt, Stefano Debei, V. Da Deppo, Pedro J. Gutiérrez, Björn Davidsson, Maurizio Pajola, J.-R. Kramm, Marc Hofmann, Cecilia Tubiana, Géza Kovács, F. Scholten, Rafael Rodrigo, A. Gicquel, Detlef Koschny, Nicolas Thomas, Olivier Groussin, Carsten Güttler, Michael Küppers, J. J. López-Moreno, Mohamed Ramy El-Maarry, S. Höfner, Hans Rickman, Cesare Barbieri, S. Zitzmann, Jakob Deller, Ivano Bertini, Michael F. A'Hearn, Francesco Marzari, J. Knollenberg, Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Physics and Astronomy [Uppsala], Uppsala University, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Akademie der Wissenschaften zu Göttingen, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Trieste (OAT), Istituto Nazionale di Astrofisica (INAF), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Department of Mechatronics, Optics and Mechanical Engineering Informatics (MOMEI), Budapest University of Technology and Economics [Budapest] (BME), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Department of Information Engineering [Padova] (DEI), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Max-Planck-Institut für Sonnensystemforschung (MPS), Technische Universität Braunschweig [Braunschweig], Universität Bern [Bern], Universita degli Studi di Padova, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), European Space Agency (ESA)-European Space Agency (ESA), Polska Akademia Nauk (PAN), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), IMPEC - LATMOS, Consejo Superior de Investigaciones Científicas [Spain] (CSIC), European Space Agency (ESA), California Institute of Technology (CALTECH)-NASA, Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), and ITA
Subjects: Asteroiden und Kometen, Comets: general, Comets: individual: 67P/Churyumov-Gerasimenko, Radiation mechanisms: thermal, 67P/Churyumov-Gerasimenko, 010504 meteorology & atmospheric sciences, Terrain, Astrophysics, Heat sink, 01 natural sciences, Mantle (geology), individual: 67P/Churyumov-Gerasimenko [Comets], 0103 physical sciences, Radiative transfer, Comets, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Comets, 67P/Churyumov-Gerasimenko, Radiation mechanisms: thermal, comets: general, Diurnal temperature variation, Planetengeodäsie, general [Comets], comets: individual: 67P/Churyumov-Gerasimenko, Astronomy and Astrophysics, Mechanics, Outgassing, 13. Climate action, Space and Planetary Science, thermal [Radiation mechanisms], Thermophysics, Rosetta 67P Comets Thermal Fractures, Sublimation (phase transition)
Abstract: Full list of authors: Höfner, S.; Vincent, J. -B.; Blum, J.; Davidsson, B. J. R.; Sierks, H.; El-Maarry, M. R.; Deller, J.; Hofmann, M.; Hu, X.; Pajola, M.; Barbieri, C.; Lamy, P. L.; Rodrigo, R.; Koschny, D.; Rickman, H.; Keller, H. U.; A'Hearn, M. F.; Auger, A. -T.; Barucci, M. A.; Bertaux, J. -L. Bertini, I.; Bodewits, D.; Cremonese, G.; Da Deppo, V.; Debei, S.; De Cecco, M.; Fornasier, S.; Fulle, M.; Gicquel, A.; Groussin, O.; Gutiérrez, P. J.; Gutiérrez-Marqués, P.; Güttler, C.; Hviid, S. F.; Ip, W. -H.; Jorda, L.; Knollenberg, J.; Kovacs, G.; Kramm, J. -R.; Kührt, E.; Küppers, M.; La Forgia, F.; Lazzarin, M.; Lopez-Moreno, J. J.; Marzari, F.; Michalik, H.; Moissl-Fraund, R.; Moreno, F.; Mottola, S.; Naletto, G.; Oklay, N.; Preusker, F.; Scholten, F.; Shi, X.; Thomas, N.; Toth, I.; Tubiana, C.; Zitzmann, S., The camera OSIRIS on board Rosetta obtained high-resolution images of the nucleus of comet 67P/Churyumov-Gerasimenko (67P). Great parts of the nucleus surface are composed of fractured terrain. Aims. Fracture formation, evolution, and their potential relationship to physical processes that drive activity are not yet fully understood. Observed temperatures and gas production rates can be explained or interpreted with the presence of fractures by applying appropriate modelling methods. Methods. We followed a transient thermophysical model approach that includes radiative, conductive, and water-ice sublimation fluxes by considering a variety of heliocentric distances, illumination conditions, and thermophysical properties for a set of characteristic fracture geometries on the nucleus of 67P. We computed diurnal temperatures, heat fluxes, and outgassing behaviour in order to derive and distinguish the influence of the mentioned parameters on fractured terrain. Results. Our analysis confirms that fractures, as already indicated by former studies about concavities, deviate from flat-terrain topographies with equivalent properties, mostly through the effect of self-heating. Compared to flat terrain, illuminated cometary fractures are generally warmer, with smaller diurnal temperature fluctuations. Maximum sublimation rates reach higher peaks, and dust mantle quenching effects on sublimation rates are weaker. Consequently, the rough structure of the fractured terrain leads to significantly higher inferred surface thermal inertia values than for flat areas with identical physical properties, which might explain the range of measured thermal inertia on 67P. Conclusions. At 3.5 AU heliocentric distance, sublimation heat sinks in fractures converge to maximum values >50 W / m2 and trigger dust activity that can be related mainly to H2O. Fractures are likely to grow through the erosive interplay of alternating sublimation and thermal fatigue. © ESO, 2017., OSIRIS was built by a consortium led by the Max-Planck-Institut fur Sonnensystemforschung, Gottingen, Germany, in collaboration with CISAS, University of Padova, Italy, the Laboratoire d'Astrophysique de Marseille, France, the Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain, the Scientific Support OCE of the European Space Agency, Noordwijk, The Netherlands, the Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, the Universidad Politecnica de Madrid, Spain, the Department of Physics and Astronomy of Uppsala University, Sweden, and the Institut fur Datentechnik und Kommunikationsnetze der Technischen Universitat Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MINECO), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. We thank the Rosetta Science Ground Segment at ESAC, the Rosetta Mission Operations Centre at ESOC and the Rosetta Project at ESTEC for their outstanding work enabling the science return of the Rosetta Mission. The first author also wishes to thank the MPS for funding a research stipend, B. Gundlach for the helpful discussions of the application of his porous aggregate model, ITP Engines UK for providing a Ph.D. student research license of ESATAN-TMS (https://www.esatan-tms.com), which was used in this analysis, and the MPS Solar Orbiter Team for the funding of this licence. The authors gratefully acknowledge the referee work of Nalin Samarasinha, whose comments were very helpful in increasing the quality of this paper.
Published: 2017

23. Observations and analysis of a curved jet in the coma of comet 67P/Churyumov-Gerasimenko

Author: Jörg Knollenberg, Monica Lazzarin, M. F. A'Hearn, Michael Küppers, Jong-Shinn Wu, J.-C. Lee, Ivano Bertini, M. A. Barucci, Wing-Huen Ip, Laurent Jorda, L. M. Lara, P. L. Lamy, Horst Uwe Keller, G. Cremonese, Agata Rozek, Cesare Barbieri, Maurizio Pajola, Nicolas Thomas, J. J. Lopez-Moreno, C. C. Su, J.-R. Kramm, S. Debet, M. De Cecco, Cecilia Tubiana, Giampiero Naletto, F. La Forgia, S. Fornasier, Ekkehard Kührt, Stefano Mottola, I. L. Lai, Francesco Marzari, J. Agarwal, Detlef Koschny, Zhong-Yi Lin, Stubbe F. Hviid, C. Güttler, V. Da Deppo, Géza Kovács, Stephen C. Lowry, R. Rodrigo, Hans Rickman, Marco Fulle, P. J. Gutierrez, Olivier Groussin, Dennis Bodewits, Harald Michalik, J. L. Bertaux, B. J. R. Davidsson, Holger Sierks, N. Oklay, J. B. Vincent, Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Institute of Space Science [Taiwan], Department of Mechanical Engineering [NCTU], National Chiao Tung University (NCTU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Department of Atmospheric Sciences [Taoyuan City], Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Università degli Studi di Padova = University of Padua (Unipd), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Physics and Astronomy [Uppsala], Uppsala University, Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institute of Planetary Research, German Aerospace Center (DLR), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Centre for Astrophysics and Planetary Science [Canterbury] (CAPS), University of Kent [Canterbury], Department of Information Engineering, Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), National funding agencies of Germany (DLR), France (CNES), Italy (Agenzia Spaziale Italiana), Spain (Ministerio de Educación, Cultura y Deporte), Sweden (Swedish National Space Board), ESA, Ministry of Science and Technology of Taiwan, Max-Planck-Institut für Sonnensystemforschung (MPS), Universita degli Studi di Padova, European Space Agency (ESA)-European Space Agency (ESA), Consiglio Nazionale delle Ricerche [Roma] (CNR), European Space Agency (ESA), Universität Bern [Bern], Ministerio de Educación, Cultura y Deporte (España), Swedish National Space Board, European Space Agency, Agenzia Spaziale Italiana, Centre National D'Etudes Spatiales (France), German Centre for Air and Space Travel, National Science and Technology Development Agency (Thailand), ITA, USA, GBR, FRA, and DEU
Subjects: 67P/Churyumov-Gerasimenko, Gravity (chemistry), 010504 meteorology & atmospheric sciences, Terminal velocity, 530 Physics, Comet, Equator, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Coma (optics), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, individual: 67P/Churyumov-Gerasimenko [Comets], 0103 physical sciences, medicine, comets, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Comets: individual: 67P/Churyumov-Gerasimenko, Jet (fluid), Astronomy and Astrophysics, Space and Planetary Science, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 520 Astronomy, 620 Engineering, medicine.anatomical_structure, Drag, Astrophysics::Earth and Planetary Astrophysics, Nucleus, Astrophysics - Earth and Planetary Astrophysics
Abstract: Aims. We analyze the physical properties and dynamical origin of a curved jet of comet 67P/Churyumov-Gerasimenko that was observed repeatedly in several nucleus rotations starting on May 30 and persisting until early August, 2015. Methods. We simulated the motion of dust grains ejected from the nucleus surface under the influence of the gravity and viscous drag effect of the expanding gas flow from the rotating nucleus. Results. The formation of the curved jet is a combination of the size of the dust particles (∼0.1-1 mm) and the location of the source region near the nucleus equator. This enhances the spiral feature of the collimated dust stream after the dust is accelerated to a terminal speed on the order of m s. © ESO, 2016., The support of the national funding agencies of Germany (Deutschen Zentrums fur Luft- und Raumfahrt), France (Centre National d'Etudes Spatiales), Italy (Agenzia Spaziale Italiana), Spain (Ministerio de Educacion, Cultura y Deporte), Sweden (Swedish National Space Board; grant no. 74/10:2), and the ESA Technical Directorate is gratefully acknowledged. This work was also supported by grant number NSC 102-2112-M-008-013-MY3 and MOST 104-2119-M-008-024 from the Ministry of Science and Technology of Taiwan. We are indebted to the whole Rosetta mission team, Science Ground Segment, and Rosetta Mission Operation Control for their hard work making this mission possible.
Published: 2016

24. Physical properties and dynamical relation of the circular depressions on comet 67P/Churyumov-Gerasimenko

Author: M. F. A'Hearn, Carsten Güttler, F. La Forgia, Olivier Groussin, J.-C. Lee, I. L. Lai, Nilda Oklay, Steve Boudreault, Francesco Marzari, Sebastien Besse, P. J. Gutiérrez, Giampiero Naletto, Holger Sierks, Björn Davidsson, V. Da Deppo, Marco Fulle, Cecilia Tubiana, Philippe Lamy, Detlef Koschny, J.-R. Kramm, Nicolas Thomas, H. U. Keller, Sonia Fornasier, Stefano Debei, M. De Cecco, J. J. López-Moreno, Monica Lazzarin, Jörg Knollenberg, Michael Küppers, Ekkehard Kührt, Y.-C. Cheng, Simone Marchi, Géza Kovács, L. M. Lara, Harald Michalik, Mohamed Ramy El-Maarry, Wing-Huen Ip, Jessica Agarwal, Laurent Jorda, Hans Rickman, Y. Li, J. B. Vincent, Stubbe F. Hviid, Stefano Mottola, M. A. Barucci, Maurizio Pajola, Cesare Barbieri, Stephen C. Lowry, J. L. Bertaux, E. Toth, Ivano Bertini, Gabriele Cremonese, Zhong-Yi Lin, R. Rodrigo, Dennis Bodewits, Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Institute of Space Science [Taiwan], Department of Atmospheric Sciences [Taoyuan City], Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Universita degli Studi di Padova, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Physics and Astronomy [Uppsala], Uppsala University, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), Department of Industrial Engineering [Padova], University of Trento [Trento], Physikalisches Institut [Bern], Universität Bern [Bern], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Centre for Astrophysics and Planetary Science [Canterbury] (CAPS), University of Kent [Canterbury], Solar System Exploration Research Virtual Institute (SSERVI), Southwest Research Institute [Boulder] (SwRI), Department of Information Engineering [Padova] (DEI), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Ministerio de Educación, Cultura y Deporte (España), Swedish National Space Board, European Space Agency, Agenzia Spaziale Italiana, Centre National D'Etudes Spatiales (France), German Centre for Air and Space Travel, Ministry of Science and Technology (Taiwan), ITA, USA, GBR, FRA, DEU, Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Università degli Studi di Padova = University of Padua (Unipd), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Universität Bern [Bern] (UNIBE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)
Subjects: Insolation, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, Comet, Astrophysics, 01 natural sciences, Asymmetry, symbols.namesake, individual: 67P/Churyumov-Gerasimenko [Comets], Comet nucleus, 0103 physical sciences, Size frequency, Pareto distribution, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, media_common, Physics, Comets: individual: 67P/Churyumov-Gerasimenko, Astronomy and Astrophysics, Space and Planetary Science, Astronomy, comets: individual: 67P/Churyumov-Gerasimenko, 13. Climate action, Global distribution, symbols, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Aims. We aim to characterize the circular depressions of comet 67P/Churyumov-Gerasimenko and investigate whether such surface morphology of a comet nucleus is related to the cumulative sublimation effect since becoming a Jupiter family comet (JFC). Methods. The images from the Rosetta/OSIRIS science camera experiment are used to construct size frequency distributions of the circular depression structures on comet 67P and they are compared with those of the JFCs 81P/Wild 2, 9P/Tempel 1, and 103P/Hartley 2. The orbital evolutionary histories of these comets over the past 100 000 yr are analyzed statistically and compared with each other. Results. The global distribution of the circular depressions over the surface of 67P is charted and classified. Descriptions are given to the characteristics and cumulative size frequency distribution of the identified features. Orbital statistics of the JFCs visited by spacecraft are derived. Conclusions. The size frequency distribution of the circular depressions is found to have a similar power law distribution to those of 9P/Tempel 1 and 81P/Wild 2. This might imply that they could have been generated by the same process. Orbital integration calculation shows that the surface erosion histories of 81P/Wild 2, and 9P/Tempel 1 could be shorter than those of 67P, 103 P/Hartley 2 and 19P/Borrelly. From this point of view, the circular depressions could be dated back to the pre-JFC phase or the transneptunian phase of these comets. The north-south asymmetry in the distribution of the circular depressions could be associated with the heterogeneous structure of the nucleus of comet 67P and/or the solar insolation history. © ESO, 2016., The support of the national funding agencies of Germany (Deutschen Zentrums fur Luft- und Raumfahrt), France (Centre National d'Etudes Spatales), Italy (Agenzia Spaziale Italiana), Spain (Ministerio de Educacion, Cultura y Deporte), Sweden (Swedish National Space Board; grant No. 74/10:2), and the ESA Technical Directorate is gratefully acknowledged. We are indebted to the whole Rosetta mission team, Science Ground Segment, and Rosetta Mission Operation Control for their hard work making this mission possible. This work was also supported by grant number MOST 104-2119-M-008-024 (TANGOII), NSC 102-2112-M-008-013-MY3, and MOST 104-2111-M-008-020(Space) from the Ministry of Science and Technology of Taiwan, and FDCT grant No. 017/2014/A1 and 039/2013/A2 of Macau Special Administrative Region.
Published: 2016

25. CHANGES in the PHYSICAL ENVIRONMENT of the INNER COMA of 67P/CHURYUMOV-GERASIMENKO with DECREASING HELIOCENTRIC DISTANCE

Author: Imre Tóth, E. Kuehrt, P. J. Gutierrez, Ivano Bertini, Detlef Koschny, F. La Forgia, J.-R. Kramm, Steve Boudreault, S. Fornasier, Nicolas Thomas, J. J. Lopez-Moreno, Giampiero Naletto, Cecilia Tubiana, Francesco Marzari, Hans Rickman, Carsten Guettler, Olivier Groussin, M. A. Barucci, L. M. Lara, Monica Lazzarin, R. Rodrigo, Michael F. A'Hearn, Cesare Barbieri, A. Giquel, Michael Kueppers, Jörg Knollenberg, Colin Snodgrass, Zhong-Yi Lin, Marco Fulle, Stefano Debei, N. Oklay, Stubbe F. Hviid, P. Lamy, B. J. R. Davidsson, Géza Kovács, V. DaDeppo, J. L. Bertaux, H. U. Keller, Holger Sierks, Wing-Huen Ip, Laurent Jorda, Dennis Bodewits, G. Cremonese, M. De Cecco, Xian Shi, J. B. Vincent, Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Gauss Professor Akademie der Wissenschaften zu Göttingen, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Università degli Studi di Padova = University of Padua (Unipd), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), School of Physical Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Department of Physics and Astronomy [Uppsala], Uppsala University, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Mechanical Engineering [Padova], Department of Industrial Engineering [Padova], Università degli Studi di Padova = University of Padua (Unipd)-Università degli Studi di Padova = University of Padua (Unipd), University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Department of Information Engineering [Padova] (DEI), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Universita degli Studi di Padova, Max-Planck-Institut für Sonnensystemforschung (MPS), European Space Agency (ESA), Consiglio Nazionale delle Ricerche [Roma] (CNR), Universita degli Studi di Padova-Universita degli Studi di Padova, European Space Agency (ESA)-European Space Agency (ESA), Universität Bern [Bern], ITA, USA, GBR, FRA, DEU, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)
Subjects: 010504 meteorology & atmospheric sciences, atomic processes, comets: individual (67P/Churyumov-Gerasimenko), molecular processes, plasmas, radiation mechanisms: non-thermal, techniques: image processing, 530 Physics, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Coma (optics), Electron, Astrophysics, Spatial distribution, 01 natural sciences, comets: individual: 67P/Churyumov--Gerasimenko, 0103 physical sciences, Emission spectrum, comets, 10. No inequality, 010303 astronomy & astrophysics, Electron ionization, 0105 earth and related environmental sciences, Physics, Earth and Planetary Astrophysics (astro-ph.EP), 520 Astronomy, Astronomy and Astrophysics, 620 Engineering, Plume, Space and Planetary Science, 13. Climate action, Excitation, Astrophysics - Earth and Planetary Astrophysics
Abstract: The Wide Angle Camera of the OSIRIS instrument on board the Rosetta spacecraft is equipped with several narrowband filters that are centered on the emission lines and bands of various fragment species. These are used to determine the evolution of the production and spatial distribution of the gas in the inner coma of comet 67P with time and heliocentric distance, here between 2.6 - 1.3 AU pre-perihelion. Our observations indicate that the emission observed in the OH, OI, CN, NH, and NH2 filters is mostly produced by dissociative electron impact excitation of different parent species. We conclude that CO2 rather than H2O is a significant source of the [OI] 630 nm emission. A strong plume-like feature observed in the in CN and [OI] filters is present throughout our observations. This plume is not present in OH emission and indicates a local enhancement of the CO2/H2O ratio by as much as a factor of 3. We observed a sudden decrease in intensity levels after March 2015, which we attribute to decreased electron temperatures in the first kilometers above the nucleus surface., 6 figures, 6 tables
Published: 2016

26. Geologic mapping of the Comet 67P/Churyumov–Gerasimenko's Northern hemisphere

Author: Pedro J. Gutiérrez, F. La Forgia, Nilda Oklay, Frank Scholten, Lorenza Giacomini, M. F. A'Hearn, Dennis Bodewits, Marco Fulle, Olivier Groussin, Antoine Pommerol, Detlef Koschny, Matteo Massironi, Stubbe F. Hviid, J. Knollenberg, M. De Cecco, Francesca Ferri, Nicolas Thomas, J.-R. Kramm, Harald Michalik, V. Da Deppo, Jessica Agarwal, Giampiero Naletto, Michael Küppers, H. U. Keller, Maurizio Pajola, J. J. Lopez Moreno, Francesco Marzari, Frank Preusker, Carsten Güttler, M. A. Barucci, Wing-Huen Ip, Stefano Debei, Jean-Loup Bertaux, Rafael Rodrigo, Laurent Jorda, Ivano Bertini, Björn Davidsson, Cesare Barbieri, Cecilia Tubiana, Mohamed Ramy El-Maarry, Sonia Fornasier, Luca Penasa, Monica Lazzarin, Jean-Baptiste Vincent, Hans Rickman, Luisa Lara, Sara Magrin, Géza Kovács, Gabriele Cremonese, Ekkehard Kührt, Philippe Lamy, Sebastien Besse, Holger Sierks, Stephen C. Lowry, A.-T. Auger, Dipartimento di Geoscienze [Padova], Università degli Studi di Padova = University of Padua (Unipd), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), NASA Ames Research Center (ARC), School of Physical Sciences [Canterbury], University of Kent [Canterbury], Dipartimento di Fisica e Astronomia 'Galileo Galilei', INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Department of Information Engineering [Padova] (DEI), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Physics and Astronomy [Uppsala], Uppsala University, European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Research and Scientific Support Department, ESTEC (RSSD), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), University of Trento [Trento], Department of Industrial Engineering [Padova], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Institute of Computer and Network Engineering [Braunschweig] (IDA), European Space Agency, Swedish National Space Board, Ministerio de Economía y Competitividad (España), German Centre for Air and Space Travel, Centre National de la Recherche Scientifique (France), Agenzia Spaziale Italiana, Universita degli Studi di Padova, Universität Bern [Bern], Max-Planck-Institut für Sonnensystemforschung (MPS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), European Space Agency (ESA), European Space Agency (ESA)-European Space Agency (ESA), and Consiglio Nazionale delle Ricerche [Roma] (CNR)
Subjects: 67P/Churyumov-Gerasimenko, 010504 meteorology & atmospheric sciences, Lineament, 530 Physics, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Individual, 67P/ Churyumov-Gerasimenko, Comets, Comets: general, Methods: observational, 01 natural sciences, methods: observational – comets: general – comets: individual: 67P Churyumov Gerasimenko, Astrobiology, Paleontology, Astronomi, astrofysik och kosmologi, Astronomy and Astrophysics, Space and Planetary Science, 0103 physical sciences, Astronomy, Astrophysics and Cosmology, observational [Methods], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 520 Astronomy, Northern Hemisphere, general [Comets], Geologic map, 620 Engineering, Methods observational, 13. Climate action, Granulometry, Spatial ecology, individual: 67P/Churyumov-Gerasimenko [comets]
Abstract: The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS), the scientific imaging system onboard the Rosetta mission, has been acquiring images of the nucleus of the comet 67P/Churyumov¿Gerasimenko since 2014 August with a resolution which allows a detailed analysis of its surface. Indeed, data reveal a complex surface morphology which is likely the expression of different processes which occurred at different times on the cometary nucleus. In order to characterize these different morphologies and better understand their distribution, we performed a geologic mapping of comet¿s 67P Northern hemisphere in which features have been distinguished based on their morphological, textural and stratigraphic characteristics. For this purpose, we used narrow-angle camera images acquired in 2014 August and September with a spatial scale ranging from 1.2 to 2.4 m pixel¿1. Several different geologic units have been identified on the basis of their different surface textures, granulometry and morphology. Some of these units are distinctive and localized, whereas others are more common and distributed all over the Northern hemisphere. Moreover, different types of linear features have been distinguished on the basis of their morphology. Some of these lineaments have never been observed before on a comet and can offer important clues on the internal structures of the nucleus itself. The geologic mapping results presented here will allow us to better understand the processes which affected the nucleus¿ surface and thus the origin and evolutionary history of comet 67P/Churyumov¿Gerasimenko. © 2016 The Authors., The support of the national funding agencies of Germany (DLR), France(CNES), Italy(ASI), Spain(MEC), Sweden(SNSB) and the ESA Technical Directorate is gratefully acknowledged.
Published: 2016

27. Characterization of the Abydos region through OSIRIS high-resolution images in support of CIVA measurements

Author: Jean-Pierre Bibring, F. La Forgia, Nilda Oklay, Frank Scholten, Francesco Marzari, J. B. Vincent, Stefano Mottola, Mohamed Ramy El-Maarry, V. Da Deppo, M. De Cecco, Hans Rickman, Cesare Barbieri, Holger Sierks, Matteo Massironi, Alice Lucchetti, Jessica Agarwal, J.-R. Kramm, Stubbe F. Hviid, Marco Fulle, Olivier Groussin, Wing-Huen Ip, Laurent Jorda, Detlef Koschny, P. J. Gutiérrez, J. L. Bertaux, Nicolas Thomas, Stefano Debei, Frank Preusker, Michael Küppers, Maurizio Pajola, François Poulet, Ivano Bertini, R. Rodrigo, Carsten Güttler, H. U. Keller, Sonia Fornasier, Jörg Knollenberg, Michael F. A'Hearn, M. A. Barucci, Björn Davidsson, Cecilia Tubiana, Monica Lazzarin, Giampiero Naletto, J. J. Lopez Moreno, Philippe Lamy, Gabriele Cremonese, Ekkehard Kührt, L. M. Lara, European Space Agency, Ministerio de Educación y Ciencia (España), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Dipartimento di Geoscienze [Padova], Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Department of Physics and Astronomy [Uppsala], Uppsala University, Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Department of Information Engineering [Padova] (DEI), Universita degli Studi di Padova, Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universität Bern [Bern], Max-Planck-Institut für Sonnensystemforschung (MPS), European Space Agency (ESA)-European Space Agency (ESA), Consiglio Nazionale delle Ricerche [Roma] (CNR), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)
Subjects: 67P/Churyumov-Gerasimenko, 010504 meteorology & atmospheric sciences, comets: general, comets: individual: 67P/Churyumov-Gerasimenko, methods: data analysis, Comet, Data analysis, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Narrow angle, High resolution, Terrain, 01 natural sciences, comets: general / comets: individual: 67P/Churyumov-Gerasimenko / methods: data analysis, individual: 67P/Churyumov-Gerasimenko [Comets], Methods: data analysis, 0103 physical sciences, Size frequency, comets, data analysis [Methods], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing, Physics, Comets: individual: 67P/Churyumov-Gerasimenko, biology, general [Comets], Astronomy and Astrophysics, biology.organism_classification, Comets: general, 13. Climate action, Space and Planetary Science, Osiris
Abstract: Context. On 12 November 2014, the European mission Rosetta delivered the Philae lander on the nucleus of comet 67P/Churyumov-Gerasimenko (67P). After the first touchdown, the lander bounced three times before finally landing at a site named Abydos. Aims. We provide a morphologically detailed analysis of the Abydos landing site to support Philae's measurements and to give context for the interpretation of the images coming from the Comet Infrared and Visible Analyser (CIVA) camera system onboard the lander. Methods. We used images acquired by the OSIRIS Narrow Angle Camera (NAC) on 6 December 2014 to perform the analysis of the Abydos landing site, which provided the geomorphological map, the gravitational slope map, the size-frequency distribution of the boulders. We also computed the albedo and spectral reddening maps. Results. The morphological analysis of the region could suggest that Philae is located on a primordial terrain. The Abydos site is surrounded by two layered and fractured outcrops and presents a 0.02 km talus deposit rich in boulders. The boulder size frequency distribution gives a cumulative power-law index of -4.0 + 0.3/-0.4, which is correlated with gravitational events triggered by sublimation and/or thermal fracturing causing regressive erosion. The average value of the albedo is 5.8% at λ = 480.7 nm and 7.4% at λ = 649.2 nm, which is similar to the global albedos derived by OSIRIS and CIVA, respectively. © ESO, 2015., The support of the national funding agencies of Germany (DLR), Italy (ASI), France (CNES), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged
Published: 2016

28. The Agilkia boulders/pebbles size-frequency distributions: OSIRIS and ROLIS joint observations of 67P surface

Author: M. F. A'Hearn, Maurizio Pajola, Olivier Groussin, Detlef Koschny, M. A. Barucci, Nicolas Thomas, Björn Davidsson, H.-G. Grothues, Cecilia Tubiana, M. R. El Maarry, Cesare Barbieri, Clement Feller, Holger Sierks, Jessica Agarwal, Frank Scholten, Monica Lazzarin, Carsten Güttler, Wing-Huen Ip, Jean-Baptiste Vincent, Ivano Bertini, Laurent Jorda, Giampiero Naletto, Jakob Deller, Zhong-Yi Lin, Francesco Marzari, R. Rodrigo, J. P. Bibring, Matteo Massironi, Frank Preusker, Stefano Mottola, Stubbe F. Hviid, A. Gicquel, Marco Fulle, Marc Hofmann, Michael Küppers, F. La Forgia, P. J. Gutiérrez, M. De Cecco, Nilda Oklay, Antoine Pommerol, Harald Michalik, Maximilian Hamm, Ralf Jaumann, Steve Boudreault, V. Da Deppo, Harald Michaelis, H. U. Keller, Hans Rickman, Alice Lucchetti, J. L. Bertaux, J. J. Lopez Moreno, Philippe Lamy, Gabriele Arnold, Jörg Knollenberg, Sonia Fornasier, J.-R. Kramm, Stefano Debei, Ekkehard Kührt, L. M. Lara, Gabriele Cremonese, NASA Ames Research Center (ARC), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), INAF - Osservatorio Astronomico di Trieste (OAT), Istituto Nazionale di Astrofisica (INAF), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Department of Information Engineering [Padova] (DEI), CNR Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institute of Geological Sciences [Berlin], Department of Earth Sciences [Berlin], Free University of Berlin (FU)-Free University of Berlin (FU), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Centro de Astrobiologia [Madrid] (CAB), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), International Space Science Institute [Bern] (ISSI), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Physics and Astronomy [Uppsala], Uppsala University, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Department of Industrial Engineering [Padova], Università degli Studi di Trento (UNITN), Physikalisches Institut [Bern], Universität Bern [Bern], Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), European Space Agency (ESA)-European Space Agency (ESA), Dipartimento di Geoscienze [Padova], Institute of Computer and Network Engineering [Braunschweig] (IDA), Ministerio de Economía y Competitividad (España), Agenzia Spaziale Italiana, Centre National de la Recherche Scientifique (France), Swedish National Space Board, European Space Agency, German Centre for Air and Space Travel, Università degli Studi di Padova = University of Padua (Unipd), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Agence Spatiale Européenne = European Space Agency (ESA), Universität Bern [Bern] (UNIBE), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), and California Institute of Technology (CALTECH)-NASA
Subjects: Surface (mathematics), methods: data analysis –methods: statistical – comets: individual: 67P C-G, 010504 meteorology & atmospheric sciences, Infrared, 530 Physics, statistical [methods], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Individual, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Methods statistical, individual: 67P C-G [comets], Astronomi, astrofysik och kosmologi, 0103 physical sciences, Size frequency, data analysis [methods], 67P C-G, Methods, Astronomy, Astrophysics and Cosmology, 14. Life underwater, 010303 astronomy & astrophysics, Joint (geology), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Remote sensing, Physics, Statistical-comets, biology, methods: data Analysis methods: statistical comets: individual: 67P C G, 520 Astronomy, Astronomy, Astronomy and Astrophysics, data analysis-methods, biology.organism_classification, 620 Engineering, Space and Planetary Science, Computer Science::Computer Vision and Pattern Recognition, Astrophysics::Earth and Planetary Astrophysics, Osiris
Abstract: By using the images acquired by the OSIRIS (Optical, Spectroscopic and Infrared Remote Imaging System) and ROLIS (ROsetta Lander Imaging System) cameras, we derive the size¿ frequency distribution (SFD) of cometary pebbles and boulders covering the size range 0.05¿ 30.0 m on the Agilkia landing site. The global SFD measured on OSIRIS images, reflects the different properties of the multiple morphological units present on Agilkia, combined with selection effects related to lifting, transport and redeposition. Contrarily, the different ROLIS SFD derived on the smooth and rough units may be related to their different regolith thickness present on Agilkia. In the thicker, smoother layer, ROLIS mainly measures the SFD of the airfall population which almost completely obliterates the signature of underlying boulders up to a size of the order of 1 m. This is well matched by the power-law index derived analysing coma particles identified by the grain analyser Grain Impact Analyser and Dust Accumulator. This result confirms the important blanketing dynamism of Agilkia. The steeper SFD observed in rough terrains from 0.4 to 2 m could point out intrinsic differences between northern and southern dust size distributions, or it may suggest that the underlying boulders `peek through¿ the thinner airfall layer in the rough terrain, thereby producing the observed excess in the decimetre size range. Eventually, the OSIRIS SFD performed on the Philae landing unit may be due to water sublimation from a static population of boulders, affecting smaller boulders before the bigger ones, thus shallowing the original SFD., The support of the national funding agencies of Germany (DLR), France(CNES), Italy(ASI), Spain(MEC), Sweden(SNSB) and the ESA Technical Directorate is gratefully acknowledged.
Published: 2016

29. Possible interpretation of the precession of comet 67P/Churyumov-Gerasimenko

Author: Carsten Güttler, F. Scholten, M. A. Barucci, Imre Tóth, Wing-Huen Ip, Laurent Jorda, Claire Capanna, Detlef Koschny, Nicolas Thomas, Ivano Bertini, J. J. López-Moreno, M. De Cecco, F. La Forgia, Stefano Mottola, Jean-Loup Bertaux, Nilda Oklay, Marco Fulle, Cesare Barbieri, Michael Küppers, P. Gutierrez-Marques, Rafael Rodrigo, F. Preusker, Ekkehard Kührt, V. Da Deppo, D. Sabau, Olivier Groussin, Francesco Marzari, L. M. Lara, Jessica Agarwal, Pedro J. Gutiérrez, Sara Magrin, Maurizio Pajola, Michael F. A'Hearn, Holger Sierks, Simone Marchi, J. Knollenberg, Sonia Fornasier, Philippe Lamy, Mohamed Ramy El-Maarry, Hans Rickman, Robert Gaskell, H. U. Keller, Stefano Debei, J.-R. Kramm, Gabriele Cremonese, Björn Davidsson, Cecilia Tubiana, Monica Lazzarin, Giampiero Naletto, Jean-Baptiste Vincent, A. T. Auger, F. Moreno, Stubbe F. Hviid, Antoine Pommerol, L. Maquet, European Space Agency, Swedish National Space Board, Ministerio de Educación, Cultura y Deporte (España), Agenzia Spaziale Italiana, German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Planetary Science Institute [Tucson] (PSI), Department of Physics and Astronomy [Uppsala], Uppsala University, DLR Institute of Planetary Research, German Aerospace Center (DLR), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), International Space Science Institute [Bern] (ISSI), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Università degli Studi di Padova = University of Padua (Unipd), European Space Research and Technology Centre (ESTEC), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Industrial Engineering [Padova], University of Trento [Trento], Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), INAF - Osservatorio Astronomico di Trieste (OAT), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Operations Department (ESAC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Solar System Exploration Research Virtual Institute (SSERVI), Southwest Research Institute [Boulder] (SwRI), Department of Information Engineering [Padova] (DEI), Instituto Nacional de Técnica Aeroespacial (INTA), Center for Space and Habitability (CSH), University of Bern, ITA, USA, GBR, FRA, DEU, Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), European Space Agency (ESA), Max-Planck-Institut für Sonnensystemforschung (MPS), Universita degli Studi di Padova, Consiglio Nazionale delle Ricerche [Roma] (CNR), Universität Bern [Bern], European Space Agency (ESA)-European Space Agency (ESA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)
Subjects: Rotation period, 67P/Churyumov-Gerasimenko, Comets: general, Comets: individual: 67P/Churyumov-Gerasimenko, Astronomy and Astrophysics, Space and Planetary Science, Angular momentum, 010504 meteorology & atmospheric sciences, 530 Physics, media_common.quotation_subject, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics, comets: general / comets: individual: 67P/Churyumov-Gerasimenko, Inertia, 01 natural sciences, individual: 67P/Churyumov-Gerasimenko [Comets], Orientation (geometry), 0103 physical sciences, comets, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, media_common, Physics, 520 Astronomy, general [Comets], 500 Science, Precession, Astrophysics::Earth and Planetary Astrophysics, Right ascension, Principal axis theorem
Abstract: Context. Data derived from the reconstruction of the nucleus shape of comet 67P/Churyumov-Gerasimenko (67P) from images of the OSIRIS camera onboard ROSETTA show evidence that the nucleus rotates in complex mode. First, the orientation of the spin axis is not fixed in an inertial reference frame, which suggests a precessing motion around the angular momentum vector with a periodicity of approximately 257 h ± 12 h.Second, periodograms of the right ascension and declination (RA/Dec) coordinates of the body-frame Z axis show a very significant (higher than 99.99%) periodicity at 276 h ± 12 h, different from the rotational period of 12.40 h as previously determined from light-curve analysis. Aims. The main goal is to interpret the data and associated periodicities of the spin axis orientation in space. Methods. We analyzed the spin axis orientation in space and associated periodicities and compared them with solutions of Euler equations under the assumption that the body rotates in torque-free conditions. Statistical tests comparing the observationally derived spin axis orientation with the outcome from simulations were applied to determine the most likely inertia moments, excitation level, and periods. Results. Under the assumption that the body is solid-rigid and rotates in torque-free conditions, the most likely interpretation is that 67P is spinning around the principal axis with the highest inertia moment with a period of about 13 h. At the same time, the comet precesses around the angular momentum vector with a period of about 6.35 h. While the rotating period of such a body would be about 12.4 h, RA/Dec coordinates of the spin axis would have a periodicity of about 270 h as a result of the combination of the two aforementioned motions. Conclusions. The most direct and simple interpretation of the complex rotation of 67P requires a ratio of inertia moments significantly higher than that of a homogeneous body. © ESO, 2016., The support of the national funding agencies of Germany (DLR), France(CNES), Italy(ASI), Spain(MEC), Sweden(SNSB), and the ESA Technical Directorate is gratefully acknowledged. P.J.G. and L.M.L. particularly acknowledge funding from projects AyA 2012-32237 and ESP 2014-54062-R.
Published: 2016

30. The primordial nucleus of comet 67P/Churyumov-Gerasimenko

Author: Stefano Debei, Maria Antonieta Barucci, Holger Sierks, Philippe Lamy, Björn Davidsson, R. Moissl-Fraund, Cecilia Tubiana, Cesare Barbieri, J. J. Lopez Moreno, S. Höfner, Rafael Rodrigo, J.-R. Kramm, Michael F. A'Hearn, Marco Fulle, Colin Snodgrass, Luisa Lara, Michael Küppers, Sonia Fornasier, A.-T. Auger, Francesco Marzari, J. Knollenberg, Gabriele Cremonese, Pedro J. Gutiérrez, Ekkehard Kührt, Monica Lazzarin, Wing-Huen Ip, Laurent Jorda, Maurizio Pajola, Carsten Güttler, Mohamed Ramy El-Maarry, Jean-Baptiste Vincent, H. U. Keller, Hans Rickman, M. De Cecco, Detlef Koschny, Nicolas Thomas, C. Feller, F. La Forgia, Nilda Oklay, V. Da Deppo, Olivier Groussin, Ivano Bertini, Jean-Loup Bertaux, Géza Kovács, Giampiero Naletto, Stefano Mottola, Matteo Massironi, Stubbe F. Hviid, Department of Physics and Astronomy [Uppsala], Uppsala University, Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Universita degli Studi di Padova, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Physikalisches Institut [Bern], Universität Bern [Bern], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Dipartimento di Geoscienze [Padova], School of Physical Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), University of Trento [Trento], Department of Industrial Engineering [Padova], Université Paris Diderot - Paris 7 (UPD7), INAF - Osservatorio Astronomico di Trieste (OAT), DLR Institute of Planetary Research, German Aerospace Center (DLR), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Department of Information Engineering [Padova] (DEI), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Università degli Studi di Padova = University of Padua (Unipd), Universität Bern [Bern] (UNIBE), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), ITA, USA, GBR, FRA, DEU, ESP, TWN, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Gauss Professor Akademie der Wissenschaften zu Göttingen, International Space Science Institute [Bern] (ISSI), Agence Spatiale Européenne = European Space Agency (ESA), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), California Institute of Technology (CALTECH)-NASA, European Space Agency (ESA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)
Subjects: 67P/Churyumov-Gerasimenko, comets: individual: 67P/Churyumov-Gerasimenko, Kuiper belt: general, protoplanetary disks, Solar System, 010504 meteorology & atmospheric sciences, Comet dust, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics, 01 natural sciences, Astrobiology, 0103 physical sciences, Comets, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, comets, Kuiper belt, Physics, Comet tail, Nice model, Astronomy, Astronomy and Astrophysics, Accretion (astrophysics), 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Interstellar comet, Physics::Space Physics, comets: individual: 67P/Churyumov-Gerasimenko / Kuiper belt: general / protoplanetary disks, Astrophysics::Earth and Planetary Astrophysics, Formation and evolution of the Solar System
Abstract: We investigate the formation and evolution of comet nuclei and other trans-Neptunian objects (TNOs) in the solar nebula and primordial disk prior to the giant planet orbit instability foreseen by the Nice model. Aims. Our goal is to determine whether most observed comet nuclei are primordial rubble-pile survivors that formed in the solar nebula and young primordial disk or collisional rubble piles formed later in the aftermath of catastrophic disruptions of larger parent bodies. We also propose a concurrent comet and TNO formation scenario that is consistent with observations. Methods. We used observations of comet 67P/Churyumov-Gerasimenko by the ESA Rosetta spacecraft, particularly by the OSIRIS camera system, combined with data from the NASA Stardust sample-return mission to comet 81P/Wild 2 and from meteoritics; we also used existing observations from ground or from spacecraft of irregular satellites of the giant planets, Centaurs, and TNOs. We performed modeling of thermophysics, hydrostatics, orbit evolution, and collision physics. Results. We find that thermal processing due to short-lived radionuclides, combined with collisional processing during accretion in the primordial disk, creates a population of medium-sized bodies that are comparably dense, compacted, strong, heavily depleted in supervolatiles like CO and CO2; they contain little to no amorphous water ice, and have experienced extensive metasomatism and aqueous alteration due to liquid water. Irregular satellites Phoebe and Himalia are potential representatives of this population. Collisional rubble piles inherit these properties from their parents. Contrarily, comet nuclei have low density, high porosity, weak strength, are rich in supervolatiles, may contain amorphous water ice, and do not display convincing evidence of in situ metasomatism or aqueous alteration. We outline a comet formation scenario that starts in the solar nebula and ends in the primordial disk, that reproduces these observed properties, and additionally explains the presence of extensive layering on 67P/Churyumov-Gerasimenko (and on 9P/Tempel 1 observed by Deep Impact), its bi-lobed shape, the extremely slow growth of comet nuclei as evidenced by recent radiometric dating, and the low collision probability that allows primordial nuclei to survive the age of the solar system. Conclusions. We conclude that observed comet nuclei are primordial rubble piles, and not collisional rubble piles. We argue that TNOs formed as a result of streaming instabilities at sizes below ~400 km and that ~350 of these grew slowly in a low-mass primordial disk to the size of Triton, Pluto, and Eris, causing little viscous stirring during growth. We thus propose a dynamically cold primordial disk, which prevented medium-sized TNOs from breaking into collisional rubble piles and allowed the survival of primordial rubble-pile comets. We argue that comets formed by hierarchical agglomeration out of material that remained after TNO formation, and that this slow growth was a necessity to avoid thermal processing by short-lived radionuclides that would lead to loss of supervolatiles, and that allowed comet nuclei to incorporate ~3 Myr old material from the inner solar system.
Published: 2016

31. Photometry of dust grains of comet 67P and connection with nucleus regions

Author: Frank Scholten, M. A. Barucci, Monica Lazzarin, L. M. Lara, Hans Rickman, Sonia Fornasier, J.-R. Kramm, J. L. Bertaux, Frank Preusker, Holger Sierks, Cecilia Tubiana, Stubbe F. Hviid, Alice Lucchetti, J. B. Vincent, Stefano Mottola, Marco Fulle, Gabriele Cremonese, Jörg Knollenberg, Laurent Jorda, P. J. Gutiérrez, Stefano Debei, Maurizio Pajola, Carsten Güttler, Detlef Koschny, Giampiero Naletto, Nicolas Thomas, Cesare Barbieri, Jessica Agarwal, Michael Kueppers, Ivano Bertini, Roberto Ragazzoni, M. De Cecco, Francesco Marzari, Michael F. A'Hearn, Sara Magrin, B. J. R. Davidsson, Philippe Lamy, J. J. Lopez Moreno, E. Kürt, F. La Forgia, Nilda Oklay, V. Da Deppo, Olivier Groussin, Horst Uwe Keller, W-H. Ip, Emanuele Simioni, R. Rodrigo, ITA, USA, GBR, FRA, DEU, INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Physics and Astronomy [Uppsala], Uppsala University, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Trento [Trento], Department of Industrial Engineering [Padova], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), European Space Agency (ESA)-European Space Agency (ESA), Department of Information Engineering [Padova] (DEI), Physikalisches Institut [Bern], Universität Bern [Bern], National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Università degli Studi di Padova = University of Padua (Unipd), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Agence Spatiale Européenne = European Space Agency (ESA), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Universität Bern [Bern] (UNIBE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)
Subjects: Comets: general, Comets: individual: 67P/Churyumov-Gerasimenko, Astronomy and Astrophysics, Space and Planetary Science, 010504 meteorology & atmospheric sciences, photometry, Comet, Coma (optics), comet 67P, Astrophysics, Lambda, 01 natural sciences, Photometry (optics), Phase angle (astronomy), individual: 67P/Churyumov-Gerasimenko [Comets], 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Cosmic dust, Physics, Mineral hydration, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy, general [Comets], Full width at half maximum, 13. Climate action, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], dust grain
Abstract: Aims. Multiple pairs of high-resolution images of the dust coma of comet 67P/Churyumov-Gerasimenko have been collected by OSIRIS onboard Rosetta allowing extraction and analysis of dust grain tracks. Methods. We developed a quasi automatic method to recognize and to extract dust tracks in the Osiris images providing size, FWHM and photometric data. The dust tracks characterized by a low signal-to-noise ratio were checked manually. We performed the photometric analysis of 70 dust grain tracks observed on two different Narrow Angle Camera images in the two filters F24 and F28, centered at λ = 480.7 nm and at λ = 743.7 nm, respectively, deriving the color and the reddening of each one. We then extracted several images of the nucleus observed with the same filters and with the same phase angle to be compared with the dust grain reddening. Results. Most of the dust grain reddening is very similar to the nucleus values, confirming they come from the surface or subsurface layer. The histogram of the dust grain reddening has a secondary peak at negative values and shows some grains with values higher than the nucleus, suggesting a different composition from the surface grains. One hypothesis comes from the negative values point at the presence of hydrated minerals in the comet. © ESO, 2016., The support of the national funding agencies of Germany (DLR), Italy (ASI), France (CNES), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. We thank the ESA teams at ESAC, ESOC, and ESTEC for their work in support of the Rosetta mission.
Published: 2016

32. Characterization of OSIRIS NAC filters for the interpretation of multispectral data of comet 67P/Churyumov-Gerasimenko

Author: Carsten Güttler, Cesare Barbieri, Marco Fulle, J. J. López-Moreno, Sebastien Besse, Jörg Knollenberg, Cecilia Tubiana, Jessica Agarwal, M. De Cecco, J. L. Bertaux, Michael F. A'Hearn, Holger Sierks, Sonia Fornasier, F. La Forgia, Giampiero Naletto, Francesco Marzari, Nilda Oklay, Detlef Koschny, Ivano Bertini, Monica Lazzarin, Nicolas Thomas, Wing-Huen Ip, Laurent Jorda, Harald Michalik, V. Da Deppo, Antonella Barucci, J.-R. Kramm, R. Rodrigo, Hans Rickman, Maurizio Pajola, B. J. R. Davidsson, Philippe Lamy, Michael Küppers, Stefano Debei, P. J. Gutiérrez, Gabriele Cremonese, Ekkehard Kührt, L. M. Lara, Stubbe F. Hviid, Olivier Groussin, Horst Uwe Keller, J. B. Vincent, Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), Department of Physics and Astronomy [Uppsala], Uppsala University, Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Institut für Datentechnik und Kommunikationsnetze, Department of Information Engineering [Padova] (DEI), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), ITA, USA, GBR, FRA, DEU, ESP, Max-Planck-Institut für Sonnensystemforschung (MPS), European Space Agency (ESA)-European Space Agency (ESA), Universita degli Studi di Padova, Consiglio Nazionale delle Ricerche [Roma] (CNR), European Space Agency (ESA), Universität Bern [Bern], Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)
Subjects: 67P/Churyumov-Gerasimenko, 530 Physics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Spectral line, Optics, Methods: data analysis, Rosetta, Techniques: imaging spectroscopy, Remote sensing, Physics, Comets: individual: 67P/Churyumov-Gerasimenko, Multispectral data, biology, business.industry, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 520 Astronomy, Cometary Science, Astronomy and Astrophysics, biology.organism_classification, Reflectivity, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Space and Planetary Science, Wavelength, Astrophysics::Earth and Planetary Astrophysics, Osiris, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Context. We interpret multicolor data from OSIRISNAC for the remote-sensing exploration of comet 67P/Churyumov-Gerasimenko. Aims: We determine the most meaningful definition of color maps for the characterization of surface variegation with filters available on OSIRIS NAC. Methods: We analyzed laboratory spectra of selected minerals and olivine-pyroxene mixtures seen through OSIRIS NAC filters, with spectral methods existing in the literature: reflectance ratios, minimum band wavelength, spectral slopes, band tilt, band curvature, and visible tilt. 2O3 filters let us define regions that may significantly differ in composition. Appendices are available in electronic form at "http://www.aanda.org/10.1051/0004-6361/201525994/olm"
Published: 2015

33. Pre-hibernation performances of the OSIRIS cameras onboard the Rosetta spacecraft

Author: Francesca Ferri, Cesare Barbieri, Holger Sierks, F. La Forgia, V. Da Deppo, Michael Küppers, Maurizio Pajola, Mauro Barbieri, Ivano Bertini, Laurent Jorda, Giampiero Naletto, Sonia Fornasier, Cecilia Tubiana, Monica Lazzarin, Sara Magrin, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), Dipartimento di Fisica e Astronomia 'Galileo Galilei', CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Industrial Engineering [Padova], Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, School of Physical Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Universita degli Studi di Padova, Consiglio Nazionale delle Ricerche [Roma] (CNR), Max-Planck-Institut für Sonnensystemforschung (MPS), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)
Subjects: Physics, Solar System, biology, Spacecraft, business.industry, instrumentation: detectors, Instrumentation, Detector, Comet, Astronomy and Astrophysics, Context (language use), technique:photometry, Instrumentation: detectors, Space vehicles: instruments, Techniques: photometric, biology.organism_classification, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Calibration, Osiris, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Remote sensing
Abstract: International audience; Context. The ESA cometary mission Rosetta was launched in 2004. In the past years and until the spacecraft hibernation in June 2011, the two cameras of the OSIRIS imaging system (Narrow Angle and Wide Angle Camera. NAC and WAC) observed many different sources. On 20 January 2014 the spacecraft successfully exited hibernation to start observing the primary scientific target of the mission, comet 67P/Churyinnov-Gerasimenko. Aims. A study of the past performances of the cameras is now mandatory to be able to determine whether the system has been stable through the time and to derive, if necessary. additional analysis methods for the future precise calibration of the cometary data. Methods. The instrumental responses and filter passbands were used to estimate the efficiency of the system. A comparison with acquired images of specific calibration stars was made, and a refined photometric calibration was computed, both for the absolute flux and for the reflectivity of small bodies of the solar system. Results. We found a stability of the instrumental performances within +/- 1.5% from 2007 to 2010, with no evidence of an aging effect on the optics or detectors. The efficiency of the instrumentation is found to be as expected in the visible range, but lower than expected in the UV and IR range. A photometric calibration implementation was discussed for the two cameras. Conclusions. The calibration derived from pre hibernation phases of the mission will be checked as soon as possible after the awakening of OSIRIS and will be continuously monitored until the end of the mission in December 2015, A list of additional calibration sources has been determined that are to be observed during the forthcoming phases of the mission to ensure a better coverage across the wavelength range of the cameras and to study the possible dust contamination of the optics.
Published: 2015

34. Search for satellites near comet 67P/Churyumov-Gerasimenko using Rosetta/OSIRIS images

Author: F. La Forgia, Ivano Bertini, Nilda Oklay, Francesco Marzari, Wing-Huen Ip, Laurent Jorda, Sonia Fornasier, V. Da Deppo, Michael Küppers, Marco Fulle, Michael F. A'Hearn, J. L. Bertaux, Jörg Knollenberg, Olivier Groussin, Lorenza Giacomini, Carsten Güttler, R. Rodrigo, Harald Michalik, Horst Uwe Keller, Hans Rickman, J. B. Vincent, Maurizio Pajola, M. De Cecco, Sara Magrin, Cesare Barbieri, L. M. Lara, B. J. R. Davidsson, Ekkehard Kührt, Stefano Debei, Philippe Lamy, Gabriele Cremonese, Detlef Koschny, Nicolas Thomas, J. J. Lopez Moreno, J.-R. Kramm, Holger Sierks, Monica Lazzarin, Cecilia Tubiana, Matteo Massironi, F. Moreno, Stubbe F. Hviid, P. J. Gutiérrez, Stefano Mottola, M. A. Barucci, Giampiero Naletto, Francesca Ferri, Jessica Agarwal, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Department of Physics and Astronomy [Uppsala], Uppsala University, Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Industrial Engineering [Padova], University of Trento [Trento], Université Paris Diderot - Paris 7 (UPD7), INAF - Osservatorio Astronomico di Trieste (OAT), Dipartimento di Geoscienze [Padova], DLR Institute of Planetary Research, German Aerospace Center (DLR), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Institut für Datentechnik und Kommunikationsnetze, Department of Information Engineering [Padova] (DEI), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), ITA, USA, GBR, FRA, DEU, ESP, Universita degli Studi di Padova, Max-Planck-Institut für Sonnensystemforschung (MPS), European Space Agency (ESA)-European Space Agency (ESA), Consiglio Nazionale delle Ricerche [Roma] (CNR), Universität Bern [Bern], Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)
Subjects: Physics, Comets: individual: 67P/Churyumov-Gerasimenko, 67P/Churyumov-Gerasimenko, Solar System, Comet tail, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astronomy, Context (language use), Astronomy and Astrophysics, Comets: general, Planets and satellites: detection, Techniques: photometric, Astrophysics, Photometry, 13. Climate action, Space and Planetary Science, Comet nucleus, Interstellar comet, Hill sphere, Comets, Satellite, Small bodies - Comets - satellites - Rosetta OSIRIS
Abstract: International audience; The European Space Agency Rosetta mission reached and started escorting its main target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, at the beginning of August 2014. Within the context of solar system small bodies, satellite searches from approaching spacecraft were extensively used in the past to study the nature of the visited bodies and their collisional environ- ment.Aims. During the approaching phase to the comet in July 2014, the OSIRIS instrument onboard Rosetta performed a campaign aimed at detecting objects in the vicinity of the comet nucleus and at measuring these objects’ possible bound orbits. In addition to the scientific purpose, the search also focused on spacecraft security to avoid hazardous material in the comet’s environment.Methods. Images in the red spectral domain were acquired with the OSIRIS Narrow Angle Camera, when the spacecraft was at a distance between 5 785 km and 5 463 km to the comet, following an observational strategy tailored to maximize the scientific outcome. From the acquired images, sources were extracted and displayed to search for plausible displacements of all sources from image to image. After stars were identified, the remaining sources were thoroughly analyzed. To place constraints on the expected displacements of a potential satellite, we performed Monte Carlo simulations on the apparent motion of potential satellites within the Hill sphere.Results. We found no unambiguous detections of objects larger than ∼ 6 m within ∼ 20 km and larger than ∼ 1 m between ∼ 20 km and ∼ 110 km from the nucleus, using images with an exposure time of 0.14 s and 1.36 s, respectively. Our conclusions are consistent with independent works on dust grains in the comet coma and on boulders counting on the nucleus surface. Moreover, our analysisArticle number, page 1 of 9 shows that the comet outburst detected at the end of April 2014 was not strong enough to eject large objects and to place them intoa stable orbit around the nucleus. Our findings underline that it is highly unlikely that large objects survive for a long time around cometary nuclei.
Published: 2015

35. Astronomy

Author: F. La Forgia, Michael F. A'Hearn, Nilda Oklay, Stefano Mottola, Cecilia Tubiana, R. Kramm, Ivano Bertini, Jörg Knollenberg, Gabriele Cremonese, Jean-Loup Bertaux, R. Rodrigo, V. Da Deppo, Stefano Debei, Ekkehard Kührt, Stubbe F. Hviid, Francesco Marzari, L. M. Lara, Sonia Fornasier, P. J. Gutiérrez, Monica Lazzarin, Marco Fulle, Stephen C. Lowry, L. Sabau, K. P. Wenzel, Olivier Groussin, Hans Rickman, Horst Uwe Keller, Cesare Barbieri, Holger Sierks, Detlef Koschny, Nicolas Thomas, Maurizio Pajola, M. A. Barucci, Carsten Güttler, Colin Snodgrass, Giampiero Naletto, J. B. Vincent, Wing-Huen Ip, Laurent Jorda, Dennis Bodewits, M. De Cecco, Francesca Ferri, Jessica Agarwal, Sara Magrin, B. J. R. Davidsson, Michael Küppers, Francesco Angrilli, Philippe Lamy, Harald Michalik, J. J. Lopez Moreno, Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, School of Physical Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), DLR Institute of Planetary Research, German Aerospace Center (DLR), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), INAF - Osservatorio Astronomico di Trieste (OAT), Istituto Nazionale di Astrofisica (INAF), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Centre for Astrophysics and Planetary Science [Canterbury] (CAPS), University of Kent [Canterbury], International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Department of Physics and Astronomy [Uppsala], Uppsala University, Università degli Studi di Trento (UNITN), Department of Industrial Engineering [Padova], Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Dipartimento di Fisica [Padova], Institut für Datentechnik und Kommunikationsnetze, Department of Information Engineering [Padova] (DEI), Instituto Nacional de Técnica Aeroespacial (INTA), Max-Planck-Institut für Sonnensystemforschung (MPS), Universita degli Studi di Padova, Universität Bern [Bern], Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), European Space Agency (ESA)-European Space Agency (ESA), European Space Agency (ESA), ITA, USA, GBR, FRA, DEU, and ESP
Subjects: Comets: general, Comets: individual: 67P/Churyumov-Gerasimenko, Astronomy and Astrophysics, Space and Planetary Science, North pole, Physics, COMET 67P/CHURYUMOV-GERASIMENKO, Brightness, comets: general – comets: individual: 67P/Churyumov-Gerasimenko, biology, 530 Physics, 520 Astronomy, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astronomy, Narrow angle, Astrophysics, biology.organism_classification, 13. Climate action, Rosetta, Osiris, COMET 67P/CHURYUMOV-GERASIMENKO, Rosetta
Abstract: International audience; 67P/Churyumov-Gerasimenko is the target comet of the ESA’s Rosetta mission. After commissioning at the end of March 2014, the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) onboard Rosetta, started imaging the comet and its dust environment to investigate how they change and evolve while approaching the Sun.Methods. We focused our work on Narrow Angle Camera (NAC) orange images and Wide Angle Camera (WAC) red and visible-610 images acquired between 2014 March 23 and June 24 when the nucleus of 67P was unresolved and moving from approximately 4.3 AU to 3.8 AU inbound. During this period the 67P – Rosetta distance decreased from 5 million to 120 thousand km.Results. Through aperture photometry, we investigated how the comet brightness varies with heliocentric distance. 67P was likely already weakly active at the end of March 2014, with excess flux above that expected for the nucleus. The comet’s brightness was mostly constant during the three months of approach observations, apart from one outburst that occurred around April 30 and a second increase in flux after June 20. Coma was resolved in the profiles from mid-April. Analysis of the coma morphology suggests that most of the activity comes from a source towards the celestial north pole of the comet, but the outburst that occurred on April 30 released material in a different direction.
Published: 2015

36. Large scale dust jets in the coma of 67P/Churyumov-Gerasimenko as seen by the OSIRIS instrument on board Rosetta

Author: P. J. Gutiérrez, P. Gutiérrez Marqués, F. La Forgia, Antoine Pommerol, Sonia Fornasier, J. J. López-Moreno, Nilda Oklay, Cesare Barbieri, Giampiero Naletto, A.-T. Auger, Marco Fulle, Holger Sierks, Monica Lazzarin, Jörg Knollenberg, M. A. Barucci, V. Da Deppo, Agata Rozek, Zhong-Yi Lin, Francesco Marzari, Ekkehard Kührt, Jean-Loup Bertaux, Mohamed Ramy El-Maarry, Rafael Rodrigo, Björn Davidsson, R. Moissl–fraund, Cecilia Tubiana, Hans Rickman, F. Moreno, Stubbe F. Hviid, Maurizio Pajola, Harald Michalik, Michael Küppers, Detlef Koschny, Nicolas Thomas, Sara Magrin, M. De Cecco, Ivano Bertini, Francesca Ferri, J.-R. Kramm, Géza Kovács, Philippe Lamy, Wing-Huen Ip, Jessica Agarwal, Stephen C. Lowry, Laurent Jorda, Michael F. A'Hearn, Luisa Lara, Carsten Güttler, Dennis Bodewits, Olivier Groussin, H. U. Keller, Stefano Debei, Gabriele Cremonese, Sebastien Besse, J. B. Vincent, Stefano Mottola, M. D. Sabau, Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Centre for Astrophysics and Planetary Science [Canterbury] (CAPS), University of Kent [Canterbury], Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Università degli Studi di Padova = University of Padua (Unipd), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Physics and Astronomy [Uppsala], Uppsala University, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Industrial Engineering [Padova], University of Trento [Trento], Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), INAF - Osservatorio Astronomico di Trieste (OAT), DLR Institute of Planetary Research, German Aerospace Center (DLR), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Instituto Nacional de Técnica Aeroespacial (INTA), ITA, USA, GBR, FRA, DEU, ESP, Max-Planck-Institut für Sonnensystemforschung (MPS), Universita degli Studi di Padova, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), European Space Agency (ESA)-European Space Agency (ESA), Consiglio Nazionale delle Ricerche [Roma] (CNR), and Universität Bern [Bern]
Subjects: Comets: general, Comets: individual: 67P/Churyumov-Gerasimenko, Astronomy and Astrophysics, Space and Planetary Science, 67P/Churyumov-Gerasimenko, 010504 meteorology & atmospheric sciences, Comet dust, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Coma (optics), Astrophysics, Rotation, 01 natural sciences, Comet nucleus, 0103 physical sciences, Rosetta, medicine, comets, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, biology, Comet tail, activity, Astronomy, biology.organism_classification, medicine.anatomical_structure, 13. Climate action, Osiris, Nucleus
Abstract: Context. During the most recent perihelion passage in 2009 of comet 67P/Churyumov-Gerasimenko (67P), ground-based observations showed an anisotropic dust coma where jet-like features were detected at ~ 1.3 AU from the Sun. The current perihelion passage is exceptional as the Rosetta spacecraft is monitoring the nucleus activity since March 2014, when a clear dust coma was already surrounding the nucleus at 4.3 AU from the Sun. Subsequently, the OSIRIS camera also witnessed an outburst in activity between April 27 and 30, and since mid-July, the dust coma at rh ~ 3.7-3.6 AU preperihelion is clearly non-isotropic, pointing to the existence of dust jet-like features. Aims: We aim to ascertain on the nucleus surface the origin of the dust jet-like features detected as early as in mid-July 2014. This will help to establish how the localized comet nucleus activity compares with that seen in previous apparitions and will also help following its evolution as the comet approaches its perihelion, at which phase most of the jets were detected from ground-based observations. Determining these areas also allows locating them in regions on the nucleus with spectroscopic or geomorphological distinct characteristics. Methods: Three series of dust images of comet 67P obtained with the Wide Angle Camera (WAC) of the OSIRIS instrument onboard the Rosetta spacecraft were processed with different enhancement techniques. This was made to clearly show the existence of jet-like features in the dust coma, whose appearance toward the observer changed as a result of the rotation of the comet nucleus and of the changing observing geometry from the spacecraft. The position angles of these features in the coma together with information on the observing geometry, nucleus shape, and rotation, allowed us to determine the most likely locations on the nucleus surface where the jets originate from. Results: Geometrical tracing of jet sources indicates that the activity of the nucleus of 67P gave rise during July and August 2014 to large-scale jet-like features from the Hapi, Hathor, Anuket, and Aten regions, confirming that active regions may be present on the nucleus localized at 60° northern latitude as deduced from previous comet apparitions. There are also hints that large-scale jets observed from the ground are possibly composed, at their place of origin on the nucleus surface, of numerous small-scale features.
Published: 2015

37. Morphology and dynamics of the jets of comet 67P/Churyumov-Gerasimenko: Early-phase development

Author: Gabriele Cremonese, Ekkehard Kührt, Stefano Debei, F. La Forgia, Cesare Barbieri, Mariolino De Cecco, Stefano Mottola, Michael F. A'Hearn, Stubbe F. Hviid, Nilda Oklay, Pedro J. Gutiérrez, Giampiero Naletto, José Juan López-Moreno, Wing-Huen Ip, Zhong-Yi Lin, Laurent Jorda, Michael Küppers, N. Thomas, Luisa Lara, Jean-Loup Bertaux, Maurizio Pajola, Stephen C. Lowry, Holger Sierks, Francesco Marzari, Harald Michalik, Yu-Te Liao, J.-R. Kramm, Dennis Bodewits, Géza Kovács, Sonia Fornasier, Björn Davidsson, Marco Fulle, Philippe Lamy, Detlef Koschny, Cecilia Tubiana, Jessica Agarwal, H. U. Keller, Jörg Knollenberg, Monica Lazzarin, Agata Rozek, Rafael Rodrigo, Maria Antonietta Barucci, Hans Rickman, Olivier Groussin, J.-C. Lee, Ivano Bertini, Jean-Baptste Vincent, Ian-Lin Lai, Carsten Güttler, Vania Da Deppo, Institute of Astronomy, National Taiwan University [Taiwan] (NTU), Space Science Institute [Macau] (SSI), Macau University of Science and Technology (MUST), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Department of Earth Sciences [Chung-Li City], Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), Department of Physics and Astronomy [Uppsala], Uppsala University, Department of Industrial Engineering [Padova], University of Trento [Trento], Université Paris Diderot - Paris 7 (UPD7), INAF - Osservatorio Astronomico di Trieste (OAT), DLR Institute of Planetary Research, German Aerospace Center (DLR), Centre for Astrophysics and Planetary Science [Canterbury] (CAPS), University of Kent [Canterbury], Department of Information Engineering [Padova] (DEI), Physikalisches Institut [Bern], Universität Bern [Bern], ITA, USA, GBR, FRA, DEU, ESP, Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Università degli Studi di Padova = University of Padua (Unipd), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), and Universität Bern [Bern] (UNIBE)
Subjects: 67P/Churyumov-Gerasimenko, Brightness, 010504 meteorology & atmospheric sciences, 530 Physics, Comet dust, Astrophysics::High Energy Astrophysical Phenomena, Comet, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Potential source, comets, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Comets: individual: 67P/Churyumov-Gerasimenko, Astronomy and Astrophysics, Space and Planetary Science, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy, 13. Climate action, Sublimation (phase transition), Astrophysics::Earth and Planetary Astrophysics, Early phase
Abstract: Aims: The OSIRIS camera onboard the Rosetta spacecraft obtained close-up views of the dust coma of comet 67P. The jet structures can be used to trace their source regions and to examine the possible effect of gas-surface interaction. Methods: We analyzed the wide-angle images obtained in the special dust observation sequences between August and September 2014. The jet features detected in different images were compared to study their time variability. The locations of the potential source regions of some of the jets are identified by ray tracing. We used a ring-masking technique to calculate the brightness distribution of dust jets along the projected distance. Results: The jets detected between August and September 2014 mostly originated in the Hapi region. Morphological changes appeared over a timescale of several days in September. The brightness slope of the dust jets is much steeper than the background coma. This might be related to the sublimation or fragmentation of the emitted dust grains. Interaction of the expanding gas flow with the cliff walls on both sides of Hapi could lead to erosion and material down-fall to the nucleus surface. Appendix A is available in electronic form at "http://www.aanda.org/10.1051/0004-6361/201525961/olm"
Published: 2015

38. OSIRIS observations of meter-sized exposures of H2O ice at the surface of 67P/Churyumov-Gerasimenko and interpretation using laboratory experiments

Author: Stephen C. Lowry, F. La Forgia, Cesare Barbieri, Frank Preusker, Nilda Oklay, Antoine Pommerol, Steve Boudreault, Ivano Bertini, Monica Lazzarin, Stubbe F. Hviid, Géza Kovács, M. De Cecco, V. Da Deppo, M. A. Barucci, M. F. A'Hearn, Olivier Groussin, Holger Sierks, J.-R. Kramm, J. L. Lopez Moreno, J. L. Bertaux, P. J. Gutierrez, Marco Fulle, Carsten Güttler, Jessica Agarwal, Björn Davidsson, Frank Scholten, Detlef Koschny, Nicolas Thomas, Giampiero Naletto, Cecilia Tubiana, Harald Michalik, Philippe Lamy, Wing-Huen Ip, Laurent Jorda, Mohamed Ramy El-Maarry, Sonia Fornasier, Clement Feller, Olivier Poch, H. U. Keller, Bernhard Jost, Francesco Marzari, Hans Rickman, J. B. Vincent, Stefano Mottola, Raphael Marschall, Jörg Knollenberg, Maurizio Pajola, E. Küppers, A. Gracia-Berná, R. Rodrigo, Ekkehard Kührt, L. M. Lara, Gabriele Cremonese, Stefano Debei, A.-T. Auger, Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy [Uppsala], Uppsala University, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], DLR Institute of Planetary Research, German Aerospace Center (DLR), School of Physical Sciences [Canterbury], University of Kent [Canterbury], Department of Industrial Engineering [Padova], CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Institut für Datentechnik und Kommunikationsnetze, Universität Bern [Bern], Universita degli Studi di Padova, Max-Planck-Institut für Sonnensystemforschung (MPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), IMPEC - LATMOS, Technische Universität Braunschweig [Braunschweig], Consiglio Nazionale delle Ricerche [Roma] (CNR), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Spain] (CSIC), European Space Agency (ESA)-European Space Agency (ESA), Polska Akademia Nauk (PAN), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), ITA, USA, GBR, FRA, and DEU
Subjects: Physics, Brightness, Spots, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Techniques: image processing, Stratification (water), Astronomy and Astrophysics, Mass wasting, Astrophysics, Debris, Comets: general, Methods: laboratory: solid state, Space and Planetary Science, Image processing, 13. Climate action, Sublimation (phase transition), comets: general – techniques: image processing – methods: laboratory: solid state, comets, Visible spectrum
Abstract: International audience; Since OSIRIS started acquiring high-resolution observations of the surface of the nucleus of comet 67P/Churyumov-Gerasimenko, over one hundred meter-sized bright spots have been identified in numerous types of geomorphologic regions, but mostly located in areas receiving low insolation. The bright spots are either clustered, in debris fields close to decameter-high cliffs, or isolated without structural relation to the surrounding terrain. They can be up to ten times brighter than the average surface of the comet at visible wavelengths and display a significantly bluer spectrum. They do not exhibit significant changes over a period of a few weeks. All these observations are consistent with exposure of water ice at the surface of boulders produced by dislocation of the weakly consolidated layers that cover large areas of the nucleus. Laboratory experiments show that under simulated comet surface conditions, analog samples acquire a vertical stratification with an uppermost porous mantle of refractory dust overlaying a layer of hard ice formed by recondensation or sintering under the insulating dust mantle. The evolution of the visible spectrophotometric properties of samples during sublimation is consistent with the contrasts of brightness and color seen at the surface of the nucleus. Clustered bright spots are formed by the collapse of overhangs that is triggered by mass wasting of deeper layers. Isolated spots might be the result of the emission of boulders at low velocity that are redepositioned in other regions.
Published: 2015
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39. Redistribution of particles across the nucleus of comet 67P/Churyumov-Gerasimenko

Author: Monica Lazzarin, Harald Michalik, Jean-Baptiste Vincent, Gabriele Cremonese, Cesare Barbieri, Wing-Huen Ip, Olivier Poch, H. U. Keller, Laurent Jorda, Matteo Massironi, Björn Davidsson, Giampiero Naletto, Stubbe F. Hviid, Cecilia Tubiana, I. L. Lai, Luisa Lara, P. J. Gutiérrez, Holger Sierks, Stefano Debei, Jong-Shinn Wu, M. A. Barucci, Stefano Mottola, Detlef Koschny, Sonia Fornasier, Frank Preusker, Maurizio Pajola, Jessica Agarwal, Francesco Marzari, Ekkehard Kührt, Antoine Pommerol, Nicolas Thomas, Lorenza Giacomini, M. De Cecco, F. La Forgia, C. C. Su, Raphael Marschall, Jörg Knollenberg, Frank Scholten, Michael Küppers, Nilda Oklay, Rafael Rodrigo, M. F. A'Hearn, Mohamed Ramy El-Maarry, A. Gracia-Berná, Hans Rickman, J.-R. Kramm, J. J. Lopez Moreno, Carsten Güttler, V. Da Deppo, J. L. Bertaux, Marco Fulle, Ying Liao, Ivano Bertini, P. L. Lamy, Olivier Groussin, Physikalisches Institut [Bern], Universität Bern [Bern], Department of Physics and Astronomy [Uppsala], Uppsala University, Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Geoscienze [Padova], Universita degli Studi di Padova, DLR Institute of Planetary Research, German Aerospace Center (DLR), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Dipartimento di Fisica e Astronomia 'Galileo Galilei', Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Department of Mechanical Engineering [NCTU], National Chiao Tung University (NCTU), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Institut für Datentechnik und Kommunikationsnetze, Universität Bern [Bern] (UNIBE), Università degli Studi di Padova = University of Padua (Unipd), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), ITA, USA, GBR, FRA, and DEU
Subjects: 010504 meteorology & atmospheric sciences, Ventifact, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Numerical modeling, Techniques: image processing, Astrophysics, comets – surface morphology – dust transport, 01 natural sciences, 0103 physical sciences, Thermal, medicine, Comets, Dust transport, Redistribution (chemistry), Space vehicles: instruments, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Comets: individual: 67P/Churyumov-Gerasimenko, Hydrodynamics, Astronomy and Astrophysics, Space and Planetary Science, Reptation, medicine.anatomical_structure, 13. Climate action, Aeolian processes, Surface morphology, Nucleus
Abstract: Context. We present an investigation of the surface properties of areas on the nucleus of comet 67P/Churyumov-Gerasimenko. Aims: We aim to show that transport of material from one part of the cometary nucleus to another is a significant mechanism that influences the appearance of the nucleus and the surface thermal properties. Methods: We used data from the OSIRIS imaging system onboard the Rosetta spacecraft to identify surface features on the nucleus that can be produced by various transport mechanisms. We used simple calculations based on previous works to establish the plausibility of dust transport from one part of the nucleus to another. Results: We show by observation and modeling that "airfall" as a consequence of non-escaping large particles emitted from the neck region of the nucleus is a plausible explanation for the smooth thin deposits in the northern hemisphere of the nucleus. The consequences are also discussed. We also present observations of aeolian ripples and ventifacts. We show by numerical modeling that a type of saltation is plausible even under the rarified gas densities seen at the surface of the nucleus. However, interparticle cohesive forces present difficulties for this model, and an alternative mechanism for the initiation of reptation and creep may result from the airfall mechanism. The requirements on gas density and other parameters of this alternative make it a more attractive explanation for the observations. The uncertainties and implications are discussed.
Published: 2015

40. Geomorphology and spectrophotometry of Philae's landing site on comet 67P/Churyumov-Gerasimenko

Author: H. U. Keller, Michael Küppers, Cesare Barbieri, Wing-Huen Ip, Laurent Jorda, Harald Michalik, Frank Preusker, Marco Fulle, Ivano Bertini, Lorenza Giacomini, Detlef Koschny, Mohamed Ramy El-Maarry, Pedro J. Gutiérrez, Carsten Güttler, Michael F. A'Hearn, Jean-Loup Bertaux, Nicolas Thomas, Olivier Groussin, Hans Rickman, Emanuele Simioni, M. De Cecco, Luisa Lara, Sonia Fornasier, F. La Forgia, Dennis Bodewits, Frank Scholten, Nilda Oklay, Francesco Marzari, J. J. Lopez Moreno, Gabriele Cremonese, Jörg Knollenberg, Sara Magrin, M. A. Barucci, V. Da Deppo, I. Hall, Rafael Rodrigo, Ekkehard Kührt, Maurizio Pajola, Francesca Ferri, Philippe Lamy, Jessica Agarwal, Stefano Debei, Giampiero Naletto, A.-T. Auger, Antoine Pommerol, Matteo Massironi, Stubbe F. Hviid, Sebastien Besse, Björn Davidsson, Cecilia Tubiana, Monica Lazzarin, J.-R. Kramm, J. B. Vincent, Stefano Mottola, Holger Sierks, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Universita degli Studi di Padova, Dipartimento di Geoscienze [Padova], Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, DLR Institute of Planetary Research, German Aerospace Center (DLR), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Department of Industrial Engineering [Padova], CNR Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), Physikalisches Institut [Bern], Universität Bern [Bern], Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Centro de Astrobiologia [Madrid] (CAB), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), International Space Science Institute [Bern] (ISSI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Physics and Astronomy [Uppsala], Uppsala University, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Trento [Trento], Université Paris Diderot - Paris 7 (UPD7), INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Institut für Datentechnik und Kommunikationsnetze, Università degli Studi di Padova = University of Padua (Unipd), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Universität Bern [Bern] (UNIBE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), ITA, USA, GBR, FRA, DEU, and ESP
Subjects: Solar System, Comet, Data analysis, 67P Churyumov-Gerasimenko, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics, Residual, 67P/C-G, Photometry, Photometry (optics), Comets: general, Comets: individual: 67P/Churyumov-Gerasimenko, Methods: data analysis, Techniques: photometric, Blue filter, Spectrophotometry, Spectral slope, Comets, medicine, Geomorphology, Remote sensing, [PHYS]Physics [physics], Physics, biology, medicine.diagnostic_test, variegation, Astronomy and Astrophysics, geomorphology, biology.organism_classification, 13. Climate action, Space and Planetary Science, Osiris, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: International audience; On 12 November 2014 the European mission Rosetta succeeded in delivering a lander, named Philae, on the surface of one of the smallest, low-gravity and most primitive bodies of the solar system, the comet 67P/Churyumov-Gerasimenko (67P).Aims. The aim of this paper is to provide a comprehensive geomorphological and spectrophotometric analysis of Philae’s landing site (Agilkia) to give an essential framework for the interpretation of its in situ measurements.Methods. OSIRIS images, coupled with gravitational slopes derived from the 3D shape model based on stereo-photogrammetry were used to interpret the geomorphology of the site. We adopted the Hapke model, using previously derived parameters, to photometrically correct the images in orange filter (649.2 nm). The best approximation to the Hapke model, given by the Akimov parameter-less function, was used to correct the reflectance for the effects of viewing and illumination conditions in the other filters. Spectral analyses on coregistered color cubes were used to retrieve spectrophotometric properties.Results. The landing site shows an average normal albedo of 6.7% in the orange filter with variations of ∼15% and a global featureless spectrum with an average red spectral slope of 15.2%/100 nm between 480.7 nm (blue filter) and 882.1 nm (near-IR filter). The spatial analysis shows a well-established correlation between the geomorphological units and the photometric characteristics of the surface. In particular, smooth deposits have the highest reflectance a bluer spectrum than the outcropping material across the area.Conclusions. The featureless spectrum and the redness of the material are compatible with the results by other instruments that have suggested an organic composition. The observed small spectral variegation could be due to grain size effects. However, the combination of photometric and spectral variegation suggests that a compositional differentiation is more likely. This might be tentatively interpreted as the effect of the efficient dust-transport processes acting on 67P. High-activity regions might be the original sources for smooth fine-grained materials that then covered Agilkia as a consequence of airfall of residual material. More observations performed by OSIRIS as the comet approaches the Sun would help interpreting the processes that work at shaping the landing site and the overall nucleus.
Published: 2015

41. Regional surface morphology of comet 67P/Churyumov-Gerasimenko from Rosetta/OSIRIS images

Author: F. La Forgia, Wing-Huen Ip, P. J. Gutiérrez, Ivano Bertini, Laurent Jorda, Lorenza Giacomini, H. U. Keller, Jörg Knollenberg, F. Marzari, Antoine Pommerol, J. J. Lopez Moreno, Harald Michalik, Géza Kovács, Holger Sierks, Rafael Rodrigo, Frank Scholten, Stefano Debei, A. Gracia-Berná, Sebastien Besse, Ekkehard Kührt, Nilda Oklay, Philippe Lamy, Matteo Massironi, Sonia Fornasier, Simone Marchi, J. L. Bertaux, Dennis Bodewits, Giampiero Naletto, Raphael Marschall, Michael Küppers, Monica Lazzarin, Carsten Güttler, V. Da Deppo, Stubbe F. Hviid, Jean-Baptiste Vincent, Maurizio Pajola, A.-T. Auger, M. F. A'Hearn, Marco Fulle, Olivier Groussin, M. De Cecco, M. A. Barucci, J.-R. Kramm, Gabriele Cremonese, Björn Davidsson, Cecilia Tubiana, Mohamed Ramy El-Maarry, Hans Rickman, Frank Preusker, Detlef Koschny, Nicolas Thomas, Cesare Barbieri, Luisa Lara, Jessica Agarwal, Physikalisches Institut [Bern], Universität Bern [Bern], Dipartimento di Geoscienze [Padova], Universita degli Studi di Padova, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Centro de Astrobiologia [Madrid] (CAB), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), International Space Science Institute [Bern] (ISSI), Department of Physics and Astronomy [Uppsala], Uppsala University, Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche [Roma] (CNR), University of Trento [Trento], Department of Industrial Engineering [Padova], Université Paris Diderot - Paris 7 (UPD7), INAF - Osservatorio Astronomico di Trieste (OAT), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), DLR Institute of Planetary Research, German Aerospace Center (DLR), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Solar System Exploration Research Virtual Institute (SSERVI), Southwest Research Institute [Boulder] (SwRI), Institut für Datentechnik und Kommunikationsnetze, Department of Information Engineering [Padova] (DEI), Universität Bern [Bern] (UNIBE), Università degli Studi di Padova = University of Padua (Unipd), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), and National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)
Subjects: Physics, 67P/Churyumov-Gerasimenko, Comets: individual: 67P/Churyumov-Gerasimenko, biology, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Mechanical failure, Astronomy, Astronomy and Astrophysics, Astrophysics, biology.organism_classification, Methods observational, observational method, Comets: general, comet, Methods: observational, 13. Climate action, Space and Planetary Science, Aeolian processes, comet 67P/ Churyumov-Gerasimenko, comets, observational, Osiris
Abstract: The OSIRIS camera onboard the Rosetta spacecraft has been acquiring images of the comet 67P/Churyumov-Gerasimenko (67P)'s nucleus at spatial resolutions down to ~0.17 m/px ever since Aug. 2014. These images have yielded unprecedented insight into the morphological diversity of the comet's surface. This paper presents an overview of the regional morphology of comet 67P. Methods: We used the images that were acquired at orbits ~20-30 km from the center of the comet to distinguish different regions on the surface and introduce the basic regional nomenclature adopted by all papers in this Rosetta special feature that address the comet's morphology and surface processes. We used anaglyphs to detect subtle regional and topographical boundaries and images from close orbit (~10 km from the comet's center) to investigate the fine texture of the surface. Results: Nineteen regions have currently been defined on the nucleus based on morphological and/or structural boundaries, and they can be grouped into distinctive region types. Consolidated, fractured regions are the most common region type. Some of these regions enclose smooth units that appear to settle in gravitational sinks or topographically low areas. Both comet lobes have a significant portion of their surface covered by a dusty coating that appears to be recently placed and shows signs of mobilization by aeolian-like processes. The dusty coatings cover most of the regions on the surface but are notably absent from a couple of irregular large depressions that show sharp contacts with their surroundings and talus-like deposits in their interiors, which suggests that short-term explosive activity may play a significant role in shaping the comet's surface in addition to long-term sublimation loss. Finally, the presence of layered brittle units showing signs of mechanical failure predominantly in one of the comet's lobes can indicate a compositional heterogeneity between the two lobes.
Published: 2015
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42. Orbital elements of the material surrounding comet 67P/Churyumov-Gerasimenko

Author: Francesco Marzari, Holger Sierks, Cesare Barbieri, J. J. Lopez Moreno, Gabriele Cremonese, Michael F. A'Hearn, Sonia Fornasier, S. F. Hviid, R. Rodrigo, Géza Kovács, Maurizio Pajola, Olivier Groussin, Michael Küppers, R. Moissl-Fraund, Stefano Debei, Giampiero Naletto, Ekkehard Kührt, F. La Forgia, Hans Rickman, Monica Lazzarin, L. M. Lara, Nilda Oklay, Detlef Koschny, Harald Michalik, Nicolas Thomas, Ivano Bertini, Jörg Knollenberg, Sara Magrin, J. B. Vincent, P. J. Gutiérrez, V. Da Deppo, B. J. R. Davidsson, Cecilia Tubiana, Philippe Lamy, M. De Cecco, Colin Snodgrass, Marco Fulle, Wing-Huen Ip, Laurent Jorda, M. A. Barucci, Stephen C. Lowry, H. U. Keller, Dennis Bodewits, J. L. Bertaux, Carsten Güttler, J.-R. Kramm, Jessica Agarwal, Department of Physics and Astronomy [Uppsala], Uppsala University, Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Dipartimento di Fisica e Astronomia 'Galileo Galilei', Università degli Studi di Padova = University of Padua (Unipd), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Akademie der Wissenschaften zu Göttingen, Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste (OAT), DLR Institute of Planetary Research, German Aerospace Center (DLR), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Centre for Astrophysics and Planetary Science [Canterbury] (CAPS), University of Kent [Canterbury], Institut für Datentechnik und Kommunikationsnetze, School of Physical Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Max-Planck-Institut für Sonnensystemforschung (MPS), Universita degli Studi di Padova, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), European Space Agency (ESA)-European Space Agency (ESA), Consiglio Nazionale delle Ricerche [Roma] (CNR), Universität Bern [Bern], ITA, USA, GBR, FRA, DEU, and ESP
Subjects: Comets: individual: 67P/Churyumov-Gerasimenko, Orbital elements, Physics, 67P/Churyumov-Gerasimenko, 530 Physics, Comet, astrometry – celestial mechanics – comet: individual: 67P/Churyumov–Gerasimenko, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astronomy, Astronomy and Astrophysics, Astrophysics, Astrometry, Light curve, Celestial mechanics, Space and Planetary Science, Photometry (optics), Orbit, Hill sphere, Comets, Astrophysics::Earth and Planetary Astrophysics, Orbit determination, Astrophysics::Galaxy Astrophysics
Abstract: International audience; We investigate the dust coma within the Hill sphere of comet 67P/Churyumov-Gerasimenko.Aims. We aim to determine osculating orbital elements for individual distinguishable but unresolved slow-moving grains in the vicinity of the nucleus. In addition, we perform photometry and constrain grain sizes.Methods. We performed astrometry and photometry using images acquired by the OSIRIS Wide Angle Camera on the European Space Agency spacecraft Rosetta. Based on these measurements, we employed standard orbit determination and orbit improvement techniques.Results. Orbital elements and effective diameters of four grains were constrained, but we were unable to uniquely determine them. Two of the grains have light curves that indicate grain rotation.Conclusions. The four grains have diameters nominally in the range 0.14–0.50 m. For three of the grains, we found elliptic orbits, which is consistent with a cloud of bound particles around the nucleus. However, hyperbolic escape trajectories cannot be excluded for any of the grains, and for one grain this is the only known option. One grain may have originated from the surface shortly before observation. These results have possible implications for the understanding of the dispersal of the cloud of bound debris around comet nuclei, as well as for understanding the ejection of large grains far from the Sun.
Published: 2015

43. Spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from the OSIRIS instrument onboard the ROSETTA spacecraft

Author: J. Knollenberg, F. La Forgia, Olivier Groussin, Nilda Oklay, Sebastien Besse, M. Küppers, Wing-Huen Ip, Maurizio Pajola, H. U. Keller, V. Da Deppo, Carsten Güttler, Holger Sierks, Frank Scholten, Jean-Loup Bertaux, Francesco Marzari, Pedro Hasselmann, Detlef Koschny, S. F. Hviid, Ivano Bertini, Rafael Rodrigo, Harald Michalik, Nicolas Thomas, Gábor L. Kovács, M. F. A'Hearn, C. Feller, Laurent Jorda, Marco Fulle, Xian Shi, Stefano Debei, Fernando Moreno, Sonia Fornasier, Giampiero Naletto, Ekkehard Kührt, Stefano Mottola, P. J. Gutiérrez, Björn Davidsson, Luisa Lara, Cecilia Tubiana, Frank Preusker, Antoine Pommerol, M. De Cecco, R. Kramm, Gabriele Cremonese, Monica Lazzarin, Jean-Baptiste Vincent, M. A. Barucci, Hans Rickman, Colin Snodgrass, Cesare Barbieri, Klaus-Dieter Matz, C. Leyrat, J. J. Lopez Moreno, Philippe Lamy, Jessica Agarwal, Université Paris Diderot - Paris 7 ( UPD7 ), Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Observatorio Nacional [Rio de Janeiro], Research and Scientific Support Department, ESTEC ( RSSD ), European Space Research and Technology Centre ( ESTEC ), European Space Agency ( ESA ) -European Space Agency ( ESA ), Instituto de Astrofísica de Andalucía ( IAA ), Consejo Superior de Investigaciones Científicas [Spain] ( CSIC ), Max-Planck-Institut für Sonnensystemforschung ( MPS ), DLR Institute of Planetary Research, German Aerospace Center ( DLR ), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Universita degli Studi di Padova = University of Padua = Université de Padoue, Laboratoire d'Astrophysique de Marseille ( LAM ), Aix Marseille Université ( AMU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National d'Etudes Spatiales ( CNES ) -Centre National de la Recherche Scientifique ( CNRS ), International Space Science Institute ( ISSI ), Centro de Astrobiologia [Madrid] ( CAB ), Instituto Nacional de Técnica Aeroespacial ( INTA ) -Consejo Superior de Investigaciones Científicas [Spain] ( CSIC ), Space Research Centre [Warsaw] ( CBK ), Polska Akademia Nauk ( PAN ), Department of Physics and Astronomy [Uppsala], Uppsala University, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] ( IGEP ), Technische Universität Braunschweig [Braunschweig], Department of Astronomy [College Park], University of Maryland [College Park], IMPEC - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales ( LATMOS ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' ( CISAS ), INAF - Osservatorio Astronomico di Padova ( OAPD ), Istituto Nazionale di Astrofisica ( INAF ), CNR Institute for Photonics and Nanotechnologies ( IFN ), Consiglio Nazionale delle Ricerche [Roma] ( CNR ), Department of Industrial Engineering [Padova], University of Trento [Trento], INAF - Osservatorio Astronomico di Trieste ( OAT ), Institute of Space Science [Taiwan], National Central University [Taiwan] ( NCU ), Operations Department (ESAC), European Space Astronomy Center ( ESAC ), Institut für Datentechnik und Kommunikationsnetze, Department of Information Engineering [Padova] ( DEI ), Physikalisches Institut [Bern], Universität Bern [Bern], School of Physical Sciences [Milton Keynes], The Open University [Milton Keynes] ( OU ), ITA, USA, GBR, FRA, DEU, Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, German Aerospace Center (DLR), Università degli Studi di Padova = University of Padua (Unipd), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), International Space Science Institute [Bern] (ISSI), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], University of Maryland System-University of Maryland System, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), CNR Institute for Photonics and Nanotechnologies (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), INAF - Osservatorio Astronomico di Trieste (OAT), National Central University [Taiwan] (NCU), European Space Astronomy Centre (ESAC), Department of Information Engineering [Padova] (DEI), Universität Bern [Bern] (UNIBE), Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), European Space Agency (ESA)-European Space Agency (ESA), Max-Planck-Institut für Sonnensystemforschung (MPS), Universita degli Studi di Padova, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), and Consiglio Nazionale delle Ricerche [Roma] (CNR)
Subjects: 67P/Churyumov-Gerasimenko, Absolute magnitude, Opposition surge, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Data analysis, FOS: Physical sciences, Astrophysics, Photometry, photometric, Methods: data analysis, Geometric albedo, Spectrophotometry, Comets: individual: 67P/Churyumov-Gerasimenko, Techniques: photometric, Spectral slope, Comets, medicine, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Spacecraft, medicine.diagnostic_test, biology, business.industry, Astronomy and Astrophysics, biology.organism_classification, [ SDU.ASTR.EP ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], medicine.anatomical_structure, Space and Planetary Science, Comet, Osiris, business, Nucleus, Astrophysics - Earth and Planetary Astrophysics
Abstract: The Rosetta mission of the European Space Agency has been orbiting the comet 67P/Churyumov-Gerasimenko (67P) since August 2014 and is now in its escort phase. A large complement of scientific experiments designed to complete the most detailed study of a comet ever attempted are onboard Rosetta. We present results for the photometric and spectrophotometric properties of the nucleus of 67P derived from the OSIRIS imaging system, which consists of a Wide Angle Camera (WAC) and a Narrow Angle Camera (NAC). The disk-averaged phase function of the nucleus of 67P shows a strong opposition surge with a G parameter value of -0.13$\pm$0.01 in the HG system formalism and an absolute magnitude $H_v(1,1,0)$ = 15.74$\pm$0.02 mag. The integrated spectrophotometry in 20 filters covering the 250-1000 nm wavelength range shows a red spectral behavior, without clear absorption bands except for a potential absorption centered at $\sim$ 290 nm that is possibly due to SO$_2$ ice. The nucleus shows strong phase reddening, with disk-averaged spectral slopes increasing from 11\%/(100 nm) to 16\%/(100 nm) in the 1.3$^{\circ}$--54$^{\circ}$ phase angle range. The geometric albedo of the comet is 6.5$\pm$0.2\% at 649 nm, with local variations of up to $\sim$ 16\% in the Hapi region. From the disk-resolved images we computed the spectral slope together with local spectrophotometry and identified three distinct groups of regions (blue, moderately red, and red). The Hapi region is the brightest, the bluest in term of spectral slope, and the most active surface on the comet. Local spectrophotometry shows an enhancement of the flux in the 700-750 nm that is associated with coma emissions., 18, pages, 14 figures, Astronomy and Astrophysics, in press
Published: 2015

44. PHOBOS AS A D-TYPE CAPTURED ASTEROID, SPECTRAL MODELING FROM 0.25 TO 4.0 μm

Author: Dale P. Cruikshank, F. La Forgia, C. M. Dalle Ore, Ivano Bertini, Sara Magrin, Cesare Barbieri, Ted L. Roush, Monica Lazzarin, and M. Pajola
Subjects: Physics, Radiometer, biology, Infrared telescope, Astronomy, Astronomy and Astrophysics, Mars Exploration Program, planets and satellites: surfaces, biology.organism_classification, Photometry (optics), planets and satellites: individual (Phobos), techniques: imaging spectroscopy, Meteorite, Space and Planetary Science, Asteroid, Model spectrum, Osiris
Abstract: This paper describes the spectral modeling of the surface of Phobos in the wavelength range between 0.25 and 4.0 μm. We use complementary data to cover this spectral range: the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System on board the ESA Rosetta spacecraft) reflectance spectrum that Pajola et al. merged with the VSK-KRFM-ISM (Videospectrometric Camera (VSK)-Combined Radiometer and Photometer for Mars (KRFM)-Imaging Spectrometer for Mars (ISM) on board the USSR Phobos 2 spacecraft) spectra by Murchie & Erard and the IRTF (NASA Infrared Telescope Facility, Hawaii, USA) spectra published by Rivkin et al. The OSIRIS data allow the characterization of an area of Phobos covering from 868 N to 90° S in latitude and from 126° W to 286° W in longitude. This corresponds chiefly to the trailing hemisphere, but with a small sampling of the leading hemisphere as well. We compared the OSIRIS results with the Trojan D-type asteroid 624 Hektor and show that the overall slope and curvature of the two bodies over the common wavelength range are very similar. This favors Phobos being a captured D-type asteroid as previously suggested. We modeled the OSIRIS data using two models, the first one with a composition that includes organic carbonaceous material, serpentine, olivine, and basalt glass, and the second one consisting of Tagish Lake meteorite and magnesium-rich pyroxene glass. The results of these models were extended to longer wavelengths to compare the VSK-KRFM-ISM and IRTF data. The overall shape of the second model spectrum between 0.25 and 4.0 μm shows curvature and an albedo level that match both the OSIRIS and Murchie & Erard data and the Rivkin et al. data much better than the first model. The large interval fit is encouraging and adds weight to this model, making it our most promising fit for Phobos. Since Tagish Lake is commonly used as a spectral analog for D-type asteroids, this provides additional support for compositional similarities between Phobos and D-type asteroids.
Published: 2013

45. Dust Environment Model of the Interstellar Comet 2I/Borisov.

Author: G. Cremonese, M. Fulle, P. Cambianica, G. Munaretto, M. T. Capria, F. La Forgia, M. Lazzarin, A. Migliorini, W. Boschin, G. Milani, A. Aletti, G. Arlic, P. Bacci, R. Bacci, E. Bryssinck, D. Carosati, D. Castellano, L. Buzzi, S. Di Rubbo, and M. Facchini
Published: 2020
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46. CHANGES IN THE PHYSICAL ENVIRONMENT OF THE INNER COMA OF 67P/CHURYUMOV–GERASIMENKO WITH DECREASING HELIOCENTRIC DISTANCE.

Author: D. Bodewits, L. M. Lara, M. F. A’Hearn, F. La Forgia, A. Gicquel, G. Kovacs, J. Knollenberg, M. Lazzarin, Z.-Y. Lin (林忠義), X. Shi, C. Snodgrass, C. Tubiana, H. Sierks, C. Barbieri, P. L. Lamy, R. Rodrigo, D. Koschny, H. Rickman, H. U. Keller, and M. A. Barucci
Published: 2016
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47. Da Terminologia a Terminologia a colori

Author: Bertaccini, F., Castagnoli, Sara, La Forgia, F., F. BERTACCINI, S. CASTAGNOLI, F. LA FORGIA, F. Bertaccini, S. Castagnoli, and F. La Forgia
Subjects: Terminologia, Didattica, Linguaggi Specialistici, Terminologia, Linguaggi Specialistici, Didattica
Abstract: Si tratta di un'introduzione al volume che testimonia i primi dieci anni del lavoro svolto all'interno del Laboratorio di Terminologia e di Traduzione Assistita dell'ex Scuola Superiore di Lingue Moderne per Interpreti e Traduttori (dall'anno 2013 Dipartimento di Interpretazione e Traduzione).
Published: 2010

48. Le istruzioni e il web: i video-tutorial su youtube

Author: LA FORGIA, FRANCESCA, Enrico Garavelli, Elina Suomela-Härmä, and F. La Forgia
Subjects: Scrittura, Linguaggio tecnico, Oralità
Abstract: L’intervento proposto – che nasce a margine di una ricerca sulle caratteristiche tipologiche e formali dei manuali di istruzioni in prospettiva di didattica della scrittura – analizza le caratteristiche linguistiche e testuali di una specifica forma comunicativa orale: i video tutorial pubblicati su Youtube. I video tutorial hanno lo scopo di fornire istruzioni per usare o per creare un determinato prodotto, ma, diversamente dai tutorial creati dalle aziende produttrici (ad esempio, quello per iTunes http://goo.gl/d3LAS), gli autori dei video presenti su Youtube sono mossi principalmente dal desiderio di condividere con gli altri utenti della rete le proprie conoscenze (siano esse il risultato di una professione o di una passione). I video tutorial sono, infatti, una delle espressioni del video blog, ossia del diario in rete espresso attraverso il video invece che la pagina scritta, e sono, prima di tutto, un modo per esprimere sé stessi e per raccontarsi (Storelli 2012). Questo significa che la maggior parte dei video si caratterizza per un tono informale e colloquiale, e per un parlato poco programmato molto simile a quello spontaneo, lontanissimo quindi dal parlato recitato dei tutorial ufficiali (Nencioni 1983). L’analisi sarà di tipo qualitativo, e si concentrerà su un numero limitato di video, scelti in modo da spaziare il più possibile tra i diversi argomenti trattati (ricette di cucina, make up, lavoro a maglia, programmi informatici, bigiotteria, ecc.), con l’obiettivo di individuare caratteristiche linguistiche comuni, ossia tratti che possano essere considerati come sistematici per questo genere. L’analisi si servirà del modello elaborato per la descrizione dei manuali di istruzioni, costruito selezionando criteri e parametri da vari studi che si sono occupati di analisi e di tipologie testuali (Berruto 1981, Hatim 1984, Lavinio 2000, Mazzoleni 2002 e 2004, Sabatini 1999, Skytte 2001), nel tentativo di fornire non solo criteri di analisi ma anche indicazioni utilizzabili nel processo di scrittura (La Forgia in preparazione// pubblicato nel 2013).
Published: 2014

49. Didattica della scrittura: I manuali di istruzioni

Author: LA FORGIA, FRANCESCA and F. La Forgia
Subjects: Comprensione e leggibilità, Scrittura tecnica, Didattica della scrittura
Abstract: Ogni giorno veniamo a contatto con testi che forniscono procedure e istruzioni: per accedere a servizi on line, per compilare documenti, per usare telefoni cellulari, perfino per lavare in modo adeguato una pentola antiaderente. Ma nonostante la diffusione ed importanza, i manuali di istruzioni sono spesso inutilmente complicati, di difficile lettura e di ancora più difficile esecuzione. Destinato principalmente ai formatori che si occupano di scrittura tecnica e professionale, e per la preparazione iniziale dei redattori tecnici, questo volume inserisce il problema della lingua dei manuali in una riflessione più ampia sulla teoria e metodologia dell’insegnamento/apprendimento della scrittura, nella convinzione che per essere capaci di redigere qualsiasi testo non sia sufficiente sapere come scrivere ma sia necessario sapere anche perché si deve scrivere in un certo modo, per produrre un contenuto corretto, adeguato e comunicativamente efficace. (IV di copertina)
Published: 2013

50. La varietà di lingua nei testi di istruzioni

Author: LA FORGIA, FRANCESCA, P. BIANCHI, N. DE BLASI, C. DE CAPRIO, F. MONTUORI, and F. La Forgia
Subjects: Relazioni transfrastiche, Testi di istruzioni, Prospettiva comunicativa, Lessico
Abstract: Seguendo la classificazione tipologica di Hatim (1984), i testi di istruzione sono testi a dominanza prescrittivo-istruzionale, il cui scopo comunicativo principale è quello di regolamentare un campo di attività determinato. In questo senso, sono testi fortemente vincolanti (Sabatini 1999: 148) «l’emittente avverte come imprescindibile […] il bisogno di restringere al massimo e comunque di regolare esplicitamente la libertà di interpretazione del testo da parte del destinatario». Regolare, o limitare, lo spazio di inferenza del destinatario significa che il mittente deve produrre un testo in cui le ambiguità proprie di ogni lingua naturale siano ridotte al minimo e che miri alla massima univocità possibile. Per ottenere ciò, deve agire su tutti i livelli pertinenti per la costruzione di un testo, cioè – usando la divisione della retorica antica – su inventio, dispositio ed elocutio (selezione delle informazioni, loro organizzazione e scelta della loro forma linguistica), con l’obiettivo di costruire un testo che presenti il giusto equilibrio tra codifica linguistica e inferenza del destinatario (nel senso in cui questi due concetti sono delineati in Prandi 2004). E sebbene alcune delle scelte che si compiono in questi tre livelli dipendano strettamente dall’appartenenza a un determinato genere all’interno dell’insieme dei testi tipologicamente a dominanza prescrittivo-istruzionale, dal tipo di destinatario a cui il testo è indirizzato (esperto, semi-esperto o non-esperto) e dal tipo di argomento, è tuttavia possibile individuare caratteristiche linguistiche comuni a tutto l’insieme dei testi d’istruzione. In questa sede, mi focalizzerò su tre aspetti che riguardano i livelli lessicale e sintattico. A livello lessicale, tralasciando l’analisi del vocabolario tecnico che è normalmente la più investigata, descriverò la necessità di costruire anche a livello di lessico “comune” sequenze lessicali (o fraseologismi) stabili che riducano al minimo la variazione. A livello sintattico, mostrerò da una parte l’esigenza di limitare il numero di nessi usato per le diverse relazioni transfrastiche, dall’altra la necessità di scegliere, dove possibile, sequenze transfrastiche che non modifichino l’ordine non marcato della prospettiva comunicativa. I testi di istruzione, infatti, sono testi che devono essere eseguiti e devono essere costruiti in modo da guidare facilmente il destinatario (che è contemporaneamente utente) attraverso le azioni che deve compiere. Di conseguenza, la lingua di questi testi deve essere il più possibile ripetitiva, sintetica e non ambigua. non tanto nella direzione di un linguaggio controllato pensato per una possibile traduzione automatica quanto piuttosto nella direzione di una scrittura controllata. (Abstract)
Published: 2012

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