Search

Your search keyword '"Thibault Cavalié"' showing total 63 results
Start Over Author "Thibault Cavalié"
63 results on '"Thibault Cavalié"'

51. Direct detection of the Enceladus water torus with Herschel

Author

M. Kidger, Dominique Bockelée-Morvan, Frank Helmich, J. Crovisier, Miriam Rengel, Paul Hartogh, R. Moreno, N. Biver, Emmanuel Lellouch, T. Cassidy, Christopher Jarchow, Thibault Cavalié, 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), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Max-Planck-Institut für Sonnensystemforschung (MPS), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université Sciences et Technologies - Bordeaux 1

Subjects
010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics, 01 natural sciences, 7. Clean energy, symbols.namesake, 0103 physical sciences, submillimetre: planetary system, STRATOSPHERE, Enceladus, Space research, CARBON-MONOXIDE, 010303 astronomy & astrophysics, Stratosphere, Physics::Atmospheric and Oceanic Physics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, JUPITER, planets and satellites: individual: Saturn, ORIGIN, Astronomy, ASTRONOMY, Astronomy and Astrophysics, Torus, Scale height, PLUME, Gas torus, SATURNS ATMOSPHERE, Space and Planetary Science, Physics::Space Physics, symbols, VAPOR, Astrophysics::Earth and Planetary Astrophysics, Titan (rocket family), EMISSION, Water vapor, planets and satellites: individual: Enceladus, techniques: spectroscopic, SYSTEM
Abstract

International audience; Cryovolcanic activity near the south pole of Saturn's moon Enceladus produces plumes of H2O-dominated gases and ice particles, which escape and populate a torus-shaped cloud. Using submillimeter spectroscopy with Herschel, we report the direct detection of the Enceladus water vapor torus in four rotational lines of water at 557, 987, 1113, and 1670 GHz, and probe its physical conditions and structure. We determine line-of-sight H2O column densities of ~4 × 1013 cm-2 near the equatorial plane, with a ~50 000 km vertical scale height. The water torus appears to be rotationally cold (e.g. an excitation temperature of 16 K is measured for the 1113 GHz line) but dynamically excited, with non-Keplerian dispersion velocities of ~2 km s-1, and appears to be largely shaped by molecular collisions. From estimates of the influx rates of torus material into Saturn and Titan, we infer that Enceladus' activity is likely to be the ultimate source of water in the upper atmosphere of Saturn, but not in Titan's. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada and the United States under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands and with major contributions from Germany, France and the US.Figures 4 and 5 are available in electronic form at http://www.aanda.org

Published
2011

52. A methodology to construct a reduced chemical scheme for 2D-3D photochemical models: Application to Saturn

Author

Thibault Cavalié, Michel Dobrijevic, F. Billebaud, 2 rue de l'Observatoire, CNRS, Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, and Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB)

Subjects
Solar System, 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Photochemistry, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], 01 natural sciences, C-4, law.invention, Atmosphere, symbols.namesake, law, Planet, 0103 physical sciences, Chemical scheme, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, 2D photochemical models, Physics, Photodissociation, Giant planet, Astronomy and Astrophysics, Hydrocarbons, Saturn, Space and Planetary Science, [SDU]Sciences of the Universe [physics], symbols, Titan (rocket family)
Abstract

We present a methodology to build a reduced chemical scheme adapted to the study of hydrocarbons in the atmospheres of giant planets and Titan. As an example, we have built a reduced chemical scheme, containing only 25 compounds and 46 reactions (including photolysis), which is well adapted to compute the abundance of the main hydrocarbons observed so far in the atmosphere of Saturn (CH 3 , CH 4 , C 2 H 2 , C 2 H 4 , C 2 H 6 , CH 3 C 2 H, C 3 H 8 and C 4 H 2 ). This scheme gives similar results, within the error bars of the model, as a 1D photochemical model using an initial chemical scheme containing 90 compounds and more than 600 reactions. As a consequence, such a methodology can be used to build a reduced scheme well adapted to future 2D (or 3D) photochemical models and GCMs.

Published
2011

53. Key reactions in the photochemistry of hydrocarbons in Neptune's stratosphere

Author

Franck Hersant, Eric Hébrard, F. Billebaud, Franck Selsis, Thibault Cavalié, Michel Dobrijevic, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), and Université Sciences et Technologies - Bordeaux 1

Subjects
Propagation of uncertainty, 010504 meteorology & atmospheric sciences, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Giant planet, Astronomy and Astrophysics, Atmospheric sciences, Photochemistry, Mole fraction, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 01 natural sciences, Reaction rate, 13. Climate action, Space and Planetary Science, Neptune, Global sensitivity analysis, 0103 physical sciences, Environmental science, 010303 astronomy & astrophysics, Stratosphere, 0105 earth and related environmental sciences
Abstract

International audience; We studied the propagation of uncertainties carried by the reaction rate coefficients in the photochemistry of Neptune's stratosphere. We showed that the uncertainties on the mole fractions of main hydrocarbons are equal to or larger than the estimated uncertainties on abundances gathered from observations. From a global sensitivity analysis study, we determined a list of 26 key reactions and discussed the 7 main key reactions that should be studied in priority to lower the uncertainties in the mole fractions computed from a photochemical model. This methodology is essential to improve the predictivity of photochemical models and, consequently, to better understand the physical and chemical processes that govern the composition of giant planet atmospheres.

Published
2010
Full Text
View/download PDF

54. The Herschel-SPIRE submillimetre spectrum of Mars

Author

José Cernicharo, M. de Val-Borro, L. Decin, J. A. D. L. Blommaert, Ganna Portyankina, M. Renge, R. Moreno, Edwin A. Bergin, M. I. Blecka, Sarah Leeks, B. M. Swinyard, T. Encrenaz, Michael Kueppers, Geoffrey A. Blake, J. Crovisier, Emmanuel Jehin, N. Biver, Matthew Joseph Griffin, E. Lellouch, L. M. Lara, F. Bensch, Dariusz C. Lis, P. J. Encrenaz, G. S. Orton, G. Davis, Daphne Stam, C. Waelkens, Alexander S. Medvedev, Dominique Bockelée-Morvan, H. J. Walker, Christopher Jarchow, Régis Courtin, Bart Vandenbussche, Eva Verdugo, Paul Hartogh, Marek Banaszkiewicz, Rudolf Schieder, Hideo Sagawa, Nicolas Thomas, Thibault Cavalié, Slawomira Szutowicz, Trevor Fulton, M. R. Kidger, Sunil Sidher, T. de Graauw, David A. Naylor, F. Billebaud, 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), Center for Mathematics and Physics, University of Aizu, Polska Akademia Nauk = Polish Academy of Sciences (PAN), Space Research Centre of Polish Academy of Sciences (CBK), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Centro de Investigaciones Biológicas (CSIC), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Ecology and Evolutionary Biology [Princeton], Princeton University, Instituut voor Sterrenkunde [Leuven], Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory (ESO), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), SRON Netherlands Institute for Space Research (SRON), Centre Alexis Vautrin (CAV), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and École normale supérieure - Paris (ENS-PSL)

Subjects
010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Fourier transform spectrometers, FOS: Physical sciences, Astrophysics, 01 natural sciences, Planet, 0103 physical sciences, Mixing ratio, Calibration, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, QB, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Atmospheric models, Detector, Astronomy and Astrophysics, Mars Exploration Program, Computational physics, 13. Climate action, Space and Planetary Science, Earth and Planetary Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Data reduction
Abstract

We have obtained the first continuous disk averaged spectrum of Mars from 450 to 1550 Ghz using the Herschel-SPIRE Fourier Transform Spectrometer. The spectrum was obtained at a constant resolution of 1.4 GHz across the whole band. The flux from the planet is such that the instrument was operated in "bright source" mode to prevent saturation of the detectors. This was the first successful use of this mode and in this work we describe the method used for observing Mars together with a detailed discussion of the data reduction techniques required to calibrate the spectrum. We discuss the calibration accuracy obtained and describe the first comparison with surface and atmospheric models. In addition to a direct photometric measurement of the planet the spectrum contains the characteristic transitions of 12CO from J 5-4 to J 13-12 as well as numerous H2O transitions. Together these allow the comparison to global atmospheric models allowing the mean mixing ratios of water and 12CO to be investigated. We find that it is possible to match the observed depth of the absorption features in the spectrum with a fixed water mixing ratio of 1 x 10-4 and a 12CO mixing ratio of 9 x 10-4, Accepted for publication in Astronomy&Astrophysics, Herschel First Results special issue

Published
2010

55. First results on Martian carbon monoxide from Herschel/HIFI observations

Author

Dominique Bockelée-Morvan, R. Lorente, Nicolas Biver, Emmanuel Jehin, Ganna Portyankina, C. Leinz, Alexander S. Medvedev, José Cernicharo, J. C. Pearson, M. de Val-Borro, M. I. Błęcka, Paul Hartogh, Marek Banaszkiewicz, G. Tofani, Rolf Güsten, Michael Küppers, B. M. Swinyard, T. Encrenaz, M. Sánchez-Portal, A. Lorenzani, C. Kramer, C. Jarchow, David A. Naylor, S. Sidher, F. Bensch, Slawomira Szutowicz, T. Klein, Raphael Moreno, Jacques Crovisier, R. Schieder, M. Kidger, Noémie Thomas, Trevor Fulton, T. de Graauw, Luisa Lara, Bart Vandenbussche, Leen Decin, E. Natale, Hideo Sagawa, Helmut Feuchtgruber, Thibault Cavalié, Edwin Bergin, Dariusz C. Lis, E. Verdugo, Emmanuel Lellouch, Geoffrey A. Blake, F. Billebaud, Christoffel Waelkens, Miriam Rengel, Joris Blommaert, Pierre Encrenaz, Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Center for Mathematics and Physics, University of Aizu, 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), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), California Institute of Technology (CALTECH), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Centro de Investigaciones Biológicas (CSIC), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Instituut voor Sterrenkunde [Leuven], Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory (ESO), Centre Alexis Vautrin (CAV), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Radioastronomie (MPIFR), Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Solar System Research (MPS), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, Smithsonian Institution-Harvard University [Cambridge], École normale supérieure - Paris (ENS Paris), and Astronomy

Subjects
[PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], RETRIEVAL, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Astrophysics, DAYGLOW, chemistry.chemical_compound, Altitude, MARS ATMOSPHERE, Mixing ratio, GENERAL-CIRCULATION MODEL, TEMPERATURE, Earth and Planetary Astrophysics (astro-ph.EP), planets and satellites: atmospheres, Martian, Physics, submillimeter: general, Astronomy and Astrophysics, Atmosphere of Mars, THERMAL STRUCTURE, CO, molecular processes, Spire, chemistry, radiative transfer, 13. Climate action, Space and Planetary Science, General Circulation Model, Volume mixing ratio, WINDS, Earth and Planetary Astrophysics, VENUS, EXPRESS, Astrophysics - Earth and Planetary Astrophysics, Carbon monoxide
Abstract

We report on the initial analysis of Herschel/HIFI carbon monoxide (CO) observations of the Martian atmosphere performed between 11 and 16 April 2010. We selected the (7-6) rotational transitions of the isotopes ^{13}CO at 771 GHz and C^{18}O at 768 GHz in order to retrieve the mean vertical profile of temperature and the mean volume mixing ratio of carbon monoxide. The derived temperature profile agrees within less than 5 K with general circulation model (GCM) predictions up to an altitude of 45 km, however, show about 12-15 K lower values at 60 km. The CO mixing ratio was determined as 980 \pm 150 ppm, in agreement with the 900 ppm derived from Herschel/SPIRE observations in November 2009., Accepted for publication in Astronomy and Astrophysics (special issue on HIFI first results); minor changes to match published version

Published
2010

56. A cometary origin for CO in the stratosphere of Saturn?

Author

Michel Dobrijevic, G. H. Moriarty-Schieven, Emmanuel Lellouch, F. Billebaud, T. Encrenaz, T. Fouchet, Paul Hartogh, Thibault Cavalié, J. Brillet, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, 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), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB), and Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS)

Subjects
Physics, planets and satellites: individual: Saturn, 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], radio lines: planetary systems, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astronomy, Astronomy and Astrophysics, Context (language use), Astrophysics, 01 natural sciences, Atmosphere, Atmospheric radiative transfer codes, 13. Climate action, Space and Planetary Science, Planet, Saturn, 0103 physical sciences, Radiative transfer, 010303 astronomy & astrophysics, Stratosphere, 0105 earth and related environmental sciences, Line (formation)
Abstract

International audience; Context. The CO(3–2) line has been observed in the atmosphere of Saturn. The CO(3–2) observation proves that an external source of CO exists in the stratosphere of the planet. Aims. We attempt to constrain the type and magnitude of the external source of CO in the atmosphere of Saturn, by observing the emission core of the CO(6–5) line. Methods. We observed the CO(6–5) line at the limbs of Saturn. We analysed the observations by means of a 1-D transport model of the atmosphere of Saturn, coupled with a radiative transfer model. Results. We obtained a high signal-to-noise ratio spectrum that confirms the existence of an external source of CO in the stratosphere of Saturn. We demonstrated that a cometary origin of CO is the most probable, an impact occurring 220±30 years ago and depositing (2.1±0.4)×1015 g of CO above 0.1 mbar. However, we cannot totally reject the possibility of CO originating (at least partially) in a steady source. Conclusions. Complete photochemical modelling of the oxygen compounds is required to determine realistic error bars of the inferred quantities and to conclude on the origin of CO.

Published
2010

57. Preparation for the Solar system observations with Herschel: Simulation of Jupiter observations with PACS

Author

Arno de Lange, Hideo Sagawa, Paul Hartogh, Miriam Rengel, Thibault Cavalié, Center for Mathematics and Physics, University of Aizu, Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, and Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB)

Subjects
Solar System, 010504 meteorology & atmospheric sciences, Infrared, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Astrophysics, 01 natural sciences, 7. Clean energy, Jovian, Jupiter, Planet, 0103 physical sciences, Spectral resolution, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Spectrometer, Astronomy, Astronomy and Astrophysics, 13. Climate action, Space and Planetary Science, Spectral atlas, Earth and Planetary Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

Observations of the water inventory as well as other chemically important species on Jupiter will be performed in the frame of the guaranteed time key project of the Herschel Space Observatory entitled "Water and related chemistry in the Solar system". Among other onboard instruments, PACS (Photodetector Array Camera and Spectrometer) will provide new data of the spectral atlas in a wide region covering the far-infrared and submillimetre domains, with an improved spectral resolution and a higher sensitivity compared to previous observations carried out by Cassini/CIRS (Composite InfraRed Spectrometer) and by ISO (Infrared Space Observatory). In order to optimise the observational plan and to prepare for the data analysis, we have simulated the expected spectra of PACS Jupiter observations. Our simulation shows that PACS will promisingly detect several H2O emission lines. As PACS is capable of spatially resolving the Jovian disk, we will be able to discern the external oxygen sources in the giant planets by exploring the horizontal distribution of water. In addition to H2O lines, some absorption lines due to tropospheric CH4, HD, PH3 and NH3 lines will be observed with PACS. Furthermore, owing to the high sensitivity of the instrument, the current upper limit on the abundance of hydrogen halides such as HCl will be also improved., Comment: to be published in Planetary and Space Science

Published
2010

58. Water and related chemistry in the solar system. A guaranteed time key programme for Herschel

Author

Slawomira Szutowicz, Michael Küppers, M. R. Kidger, N. Biver, David A. Naylor, Sunil Sidher, Emmanuel Jehin, M. I. Blecka, Dariusz C. Lis, Jean Manfroid, A. Gonzalez, Rudolf Schieder, Christopher Jarchow, Marek Banaszkiewicz, F. Billebaud, Régis Courtin, T. de Graauw, Ganna Portyankina, B. M. Swinyard, José Cernicharo, H. Walker, L. Decin, Bart Vandenbussche, F. Bensch, Gary R. Davis, P. J. Encrenaz, E. Verdugo, J. Crovisier, Thibault Cavalié, Paul Hartogh, A. de Lange, G. S. Orton, Hideo Sagawa, Nicolas Thomas, E. A. Bergin, R. Lorente, Alexander S. Medvedev, Dominique Bockelée-Morvan, G. D. Thornhill, Daphne Stam, Damien Hutsemekers, J. A. D. L. Blommaert, M. Sanchez-Portal, Geoffrey A. Blake, L. M. Lara, Emmanuel Lellouch, Thérèse Encrenaz, Miriam Rengel, R. Moreno, C. Waelkens, 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), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Centro de Investigaciones Biológicas (CSIC), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Ecology and Evolutionary Biology [Princeton], Princeton University, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Departamento de Biologia Celular, Facultad de Biologia, Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), European Southern Observatory (ESO), Laboratorio de Ecologia Isotopica, Centro de Energia Nuclear na Agricultura (CENA), California Institute of Technology (CALTECH), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Center for Mathematics and Physics, University of Aizu, SRON Netherlands Institute for Space Research (SRON), Centre Alexis Vautrin (CAV), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Harvard University-Smithsonian Institution, Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and École normale supérieure - Paris (ENS-PSL)

Subjects
Herschel spaceobservatory Water Mars Giant planets Titan Comets, Solar System, Outer planets, 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], 01 natural sciences, Astrobiology, Interplanetary dust cloud, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Enceladus, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Chemistry, Astronomy, Astronomy and Astrophysics, Mars Exploration Program, Atmosphere of Mars, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; "Water and related chemistry in the Solar System" is a Herschel Space Observatory Guaranteed-Time Key Programme. This project, approved by the European Space Agency, aims at determining the distribution, the evolution and the origin of water in Mars, the outer planets, Titan, Enceladus and the comets. It addresses the broad topic of water and its isotopologues in planetary and cometary atmospheres. The nature of cometary activity and the thermodynamics of cometary comae will be investigated by studying water excitation in a sample of comets. The D/H ratio, the key parameter for constraining the origin and evolution of Solar System species, will be measured for the first time in a Jupiter-family comet. A comparison with existing and new measurements of D/H in Oort-cloud comets will constrain the composition of pre-solar cometary grains and possibly the dynamics of the protosolar nebula. New measurements of D/H in giant planets, similarly constraining the composition of proto-planetary ices, will be obtained. The D/H and other isotopic ratios, diagnostic of Mars' atmosphere evolution, will be accurately measured in H2O and CO. The role of water vapor in Mars' atmospheric chemistry will be studied by monitoring vertical profiles of H2O and HDO and by searching for several other species (and CO and H2O isotopes). A detailed study of the source of water in the upper atmosphere of the Giant Planets and Titan will be performed. By monitoring the water abundance, vertical profile, and input fluxes in the various objects, and when possible with the help of mapping observations, we will discriminate between the possible sources of water in the outer planets (interplanetary dust particles, cometary impacts, and local sources). In addition to these inter-connected objectives, serendipitous searches will enhance our knowledge of the composition of planetary and cometary atmospheres.

Published
2009

59. First observation of CO at 345 GHz in the atmosphere of Saturn with the JCMT. New constaints on its origin

Author

Thierry Fouchet, J. Brillet, J. G. A. Wouterloot, Thibault Cavalié, E. Lellouch, G. H. Moriarty-Schieven, Michel Dobrijevic, F. Billebaud, Paul Hartogh, T. Encrenaz, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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), Herzberg Institute of Astrophysics, Conseil National de Recherches Canada (CNRC), Joint Astronomy Center (JAC), Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS)

Subjects
Physics, Solar System, spectroscopy, Outer planets, 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astronomy, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Atmosphere, Interplanetary dust cloud, 13. Climate action, Space and Planetary Science, Saturn, 0103 physical sciences, saturn, atmosphere, Mixing ratio, 010303 astronomy & astrophysics, James Clerk Maxwell Telescope, 0105 earth and related environmental sciences
Abstract

We have performed the first observation of the CO(3-2) spectral line in the atmosphere of Saturn with the James Clerk Maxwell Telescope. We have used a transport model of the atmosphere of Saturn to constrain the origin of the observed CO. The CO line is best-fit when the CO is located at pressures less than ( 15 ± 2 ) mbar with a mixing ratio of ( 2.5 ± 0.6 ) × 10 - 8 implying an external origin. By modeling the transport in Saturn’s atmosphere, we find that a cometary impact origin with an impact 200–350 years ago is more likely than continuous deposition by interplanetary dust particles (IDP) or local sources (rings/satellites). This result would confirm that comet impacts are relatively frequent and efficient providers of CO to the atmospheres of the outer planets. However, a diffuse and/or local source cannot be rejected, because we did not account for photochemistry of oxygen compounds. Finally, we have derived an upper limit of ∼ 1 × 10 - 9 on the tropospheric CO mixing ratio.

Published
2009

60. Observations of CO on Saturn and Uranus at millimeter wavelengths: New upper limit determinations

Author

Thibault Cavalié, Michel Dobrijevic, J. Brillet, F. Billebaud, E. Lellouch, Thierry Fouchet, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Solar System, 010504 meteorology & atmospheric sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Uranus, Astronomy, Planets and satellites: individual: Saturn, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Spectral line, Radio lines: solar system, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], 13. Climate action, Space and Planetary Science, Planet, Saturn, 0103 physical sciences, Mixing ratio, 010303 astronomy & astrophysics, Stratosphere, 0105 earth and related environmental sciences, Line (formation)
Abstract

International audience; We tried to detect CO lines at millimeter wavelength on Saturn and Uranus in order to better constrain the origin of this compound in the atmospheres of these planets. CO sources can be either of internal or of external origin. Methods. We recorded broad multi-band spectra of Saturn and Uranus at the frequencies of the J=1"0 and J=2"1 CO lines, at the IRAM 30m-telescope, Spain, using Lellouch et al. (2005) and Hesman et al. (2007) observing technique. Results. As we do not detect any CO line in the spectra, we derive new upper limits of the abundance of CO in the atmospheres of Saturn and Uranus. The value we obtain for Saturn (6.3×10−8, restricted to the stratosphere) is larger than the value of the CO mixing ratio in the external origin model of Noll & Larson (1991). New observations with better sensitivity and/or more observing time should enable us to state on the CO external source strength. The upper limit we derive on Uranus is slightly lower (2.7 × 10−8, restricted to the stratosphere) than the value derived from the first observation of CO on Uranus, at infrared wavelength, by Encrenaz et al. (2004). As their fluorescence model did not take scattering effects into account, we suggest that their value could be overestimated.

Published
2008

61. HIFI observations of water in the atmosphere of comet C/2008 Q3 (Garradd)

Author

L. M. Lara, Miriam Rengel, T. Klein, Nicolas Biver, M. R. Kidger, R. Moreno, Emmanuel Jehin, E. Lellouch, Michael Küppers, C. Kasemann, David A. Naylor, C. Waelkens, Pieter Dieleman, T. de Graauw, Dominique Bockelée-Morvan, Michael Olberg, E. A. Bergin, Pieter R. Roelfsema, M. Caris, Jean Manfroid, M. I. Blecka, T. Encrenaz, M. de Val-Borro, L. Decin, J. Crovisier, Slawomira Szutowicz, Christopher Jarchow, Bart Vandenbussche, José Cernicharo, J. A. D. L. Blommaert, Damien Hutsemekers, N. Thomas, Geoffrey A. Blake, Rolf Guesten, Paul Hartogh, Alexander S. Medvedev, Marek Banaszkiewicz, Arnold O. Benz, Rudolf Schieder, P. J. Encrenaz, F. Bensch, B. M. Swinyard, Dariusz C. Lis, Thibault Cavalié, Martin Emprechtinger, 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), California Institute of Technology (CALTECH), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), European Southern Observatory (ESO), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Centro de Investigaciones Biológicas (CSIC), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Instituut voor Sterrenkunde [Leuven], Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Centre Alexis Vautrin (CAV), Max-Planck-Institut für Radioastronomie (MPIFR), Onsala Space Observatory, Chalmers University of Technology [Göteborg], Astronomy, Max Planck Institute for Solar System Research (MPS), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, Smithsonian Institution-Harvard University [Cambridge], and École normale supérieure - Paris (ENS Paris)

Subjects
ROTATIONAL-EXCITATION, Electron density, 010504 meteorology & atmospheric sciences, Mean kinetic temperature, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Infrared, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Astrophysics, 01 natural sciences, RADIATIVE-TRANSFER, 0103 physical sciences, Radiation trapping, Spectroscopy, 010303 astronomy & astrophysics, SATELLITE, 0105 earth and related environmental sciences, Line (formation), Earth and Planetary Astrophysics (astro-ph.EP), Physics, LEE, submillimeter: general, Astronomy and Astrophysics, MODEL, 13. Climate action, Space and Planetary Science, comets: individual: C/2008 Q3, ODIN, VAPOR, radio lines: general, techniques: spectroscopic, Excitation, Astrophysics - Earth and Planetary Astrophysics
Abstract

High-resolution far-infrared and sub-millimetre spectroscopy of water lines is an important tool to understand the physical and chemical properties of cometary atmospheres. We present observations of several rotational ortho- and para-water transitions in comet C/2008 Q3 (Garradd) performed with HIFI on Herschel. These observations have provided the first detection of the 2_{12}-1_{01} (1669 GHz) ortho and 1_{11}-0_{00} (1113 GHz) para transitions of water in a cometary spectrum. In addition, the ground-state transition 1_{10}-1_{01} at 557 GHz is detected and mapped. By detecting several water lines quasi-simultaneously and mapping their emission we can constrain the excitation parameters in the coma. Synthetic line profiles are computed using excitation models which include excitation by collisions, solar infrared radiation, and radiation trapping. We obtain the gas kinetic temperature, constrain the electron density profile, and estimate the coma expansion velocity by analyzing the map and line shapes. We derive water production rates of 1.7-2.8 x 10^{28} s^{-1} over the range r_h = 1.83-1.85 AU., Comment: 7 figures, v2: minor changes, updated version of arXiv:1005.2969v1. Accepted for publication in Astronomy and Astrophysics, Herschel special issue on Herschel First Science Results

Published
2010

62. New constraints on the deep oxygen abundance in Uranus and Neptune

Author

Thibault Cavalié, Olivia Venot, Franck Selsis, Hersant, F., Paul Hartogh, 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), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), ECLIPSE 2016, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, and Max Planck Institute for Solar System Research (MPS)

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics::Earth and Planetary Astrophysics, Physics::Atmospheric and Oceanic Physics
Abstract

International audience; One of the great mysteries in the Solar System is how Giant Planets formed. Two main formation scenarios coexist: disk gravitational instability and core accretion. These scenarios differ not only in the time required to form planets, but also in the final composition of the planets' interiors. In this sense, heavy element abundances are key constraints and they depend on how the ices of the planetesimal that formed the cores of these planets condensed (e.g., amorphous or crystalline).Measuring the deep oxygen abundance can help differentiating the condensation processes of the planetesimal ices. Indeed, clathration needs a larger amount of water than the amorphous ice scenario. While Galileo probably failed to measure the Jovian deep oxygen abundance, Juno should shed light on this long lasting question. Measuring Saturn's deep oxygen is a goal of the entry probe that will be proposed to ESA (Mousis et al. 2016). Regarding the Ice Giants, there is no such mission planned in the near future to measure their deep oxygen abundance and it is very challenging to probe remotely below the water cloud in these planets with microwaves. Another way to constrain the deep oxygen abundance consists in using thermochemical modeling to link upper tropospheric disequilibrium species to the deep oxygen.In this paper, we apply a thermochemical and diffusion model to the ice giant tropospheres to constrain their deep oxygen abundance from CO observations. Because the results depend on the thermal structure, on the strength of tropospheric mixing, and to a lesser extent on the deep carbon abundance, we have explored a 4D parameter space (temperature, tropospheric mixing, deep oxygen and carbon abundance) for each planet to fit their upper tropospheric composition. For instance, we have computed a series of classical thermal profiles based on dry/wet adiabats and new profiles that account for the mean molecular weight gradient at the water condensation layer (following the prescription of Leconte et al. 2016). We present the results of the 4D grids and the constraints we infer from the nominal models. These 4D grids can be used in the future once the deep temperature, tropospheric mixing and methane abundance are better known.

63. Atmospheric chemistry on Uranus and Neptune

Author

Julianne I. Moses, Leigh N. Fletcher, Michael T. Roman, Thibault Cavalié, ASP 2020, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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), and Cavalié, Thibault

Subjects
010504 meteorology & atmospheric sciences, Photochemistry, General Mathematics, Uranus, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], General Physics and Astronomy, 01 natural sciences, Astrobiology, Ice Giants, Neptune, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Atmospheric Chemistry Uranus, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), General Engineering, Planetary Atmospheres, Articles, 13. Climate action, Atmospheric Chemistry, Atmospheric chemistry, Astrophysics::Earth and Planetary Astrophysics, Geology, Ice giant, Astrophysics - Earth and Planetary Astrophysics
Abstract

Comparatively little is known about atmospheric chemistry on Uranus and Neptune, because remote spectral observations of these cold, distant ``Ice Giants'' are challenging, and each planet has only been visited by a single spacecraft during brief flybys in the 1980s. Thermochemical equilibrium is expected to control the composition in the deeper, hotter regions of the atmosphere on both planets, but disequilibrium chemical processes such as transport-induced quenching and photochemistry alter the composition in the upper atmospheric regions that can be probed remotely. Surprising disparities in the abundance of disequilibrium chemical products between the two planets point to significant differences in atmospheric transport. The atmospheric composition of Uranus and Neptune can provide critical clues for unravelling details of planet formation and evolution, but only if it is fully understood how and why atmospheric constituents vary in a three-dimensional sense and how material coming in from outside the planet affects observed abundances. Future mission planning should take into account the key outstanding questions that remain unanswered about atmospheric chemistry on Uranus and Neptune, particularly those questions that pertain to planet formation and evolution, and those that address the complex, coupled atmospheric processes that operate on Ice Giants within our solar system and beyond., review paper accepted in Philos. Trans. R. Soc. A

Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results