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1. Infrared Wavefront Sensing for Adaptive Optics Assisted Galactic Center Observations with the VLT Interferometer and GRAVITY: Operation and Results

Author: Stefan Hippler, Wolfgang Brandner, Silvia Scheithauer, Martin Kulas, Johana Panduro, Peter Bizenberger, Henry Bonnet, Casey Deen, Françoise Delplancke-Ströbele, Frank Eisenhauer, Gert Finger, Zoltan Hubert, Johann Kolb, Eric Müller, Laurent Pallanca, Julien Woillez, Gérard Zins, and GRAVITY Collaboration
Subjects: near-infrared wavefront sensing, VLT interferometer, Galactic Center, CIAO, adaptive optics, SAPHIRA detector, Physics, QC1-999, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: This article describes the operation of the near-infrared wavefront sensing based Adaptive Optics (AO) system CIAO. The Coudé Infrared Adaptive Optics (CIAO) system is a central auxiliary component of the Very Large Telescope (VLT) interferometer (VLTI). It enables in particular the observations of the Galactic Center (GC) using the GRAVITY instrument. GRAVITY is a highly specialized beam combiner, a device that coherently combines the light of the four 8-m telescopes and finally records interferometric measurements in the K-band on 6 baselines simultaneously. CIAO compensates for phase disturbances caused by atmospheric turbulence, which all four 8 m Unit Telescopes (UT) experience during observation. Each of the four CIAO units generates an almost diffraction-limited image quality at its UT, which ensures that maximum flux of the observed stellar object enters the fibers of the GRAVITY beam combiner. We present CIAO performance data obtained in the first 3 years of operation as a function of weather conditions. We describe how CIAO is configured and used for observations with GRAVITY. In addition, we focus on the outstanding features of the near-infrared sensitive Saphira detector, which is used for the first time on Paranal, and show how it works as a wavefront sensor detector.
Published: 2020
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2. Thermal Imaging of Dust Hiding the Black Hole in NGC 1068

Author: Violeta Gamez Rosas, Jacob W Isbell, Walter Jaffe, Romain G Petrov, James H Leftley, Karl-Heinz Hofmann, Florentin Millour, Leonard Burtscher, Klaus Meisenheimer, Anthony Meilland, Laurens B F M Waters, Bruno Lopez, Stephane Lagarde, Gerd Weigelt, Philippe Berio, Fatme Allouche, Sylvie Robbe-Dubois, Pierre Cruzalebes, Felix Bettonvil, Thomas Henning, Jean-Charles Augereau, Pierre Antonelli, Udo Beckmann, Roy van Boekel, Philippe Bendjoya, William C Danchi, Casten Dominik, Julien Drevon, Jack F Gallimore, Uwe Graser, Matthias Heininger, Vincent Hocde, Michiel Hogerheijde, Josef Hron, Caterina M V Impellizzeri, Lucia Klarmann, Elena Kokoulina, Lucas Labadie, Michael Lehmitz, Alexis Matter, Claudia Paladini, Eric Pantin, Jörg-Uwe Pott, Dieter Schertl, Anthony Soulain, Philippe Stee, Konrad Tristram, Jozsef Varga, Julien Woillez, Sebastian Wolf, Gideon Yoffe, and Gerard Zins
Subjects: Astronomy
Abstract: In the widely accepted ‘unified model’1 solution of the classification puzzle of active galactic nuclei, the orientation of a dusty accretion torus around the central black hole dominates their appearance. In ‘type-1’ systems, the bright nucleus is visible at the centre of a face-on torus. In ‘type-2’ systems the thick, nearly edge-on torus hides the central engine. Later studies suggested evolutionary effects2 and added dusty clumps and polar winds3 but left the basic picture intact. However, recent high-resolution images4 of the archetypal type-2 galaxy NGC 10685,6, suggested a more radical revision. The images displayed a ring-like emission feature that was proposed to be hot dust surrounding the black hole at the radius where the radiation from the central engine evaporates the dust. That ring is too thin and too far tilted from edge-on to hide the central engine, and ad hoc foreground extinction is needed to explain the type-2 classification. These images quickly generated reinterpretations of the dichotomy between types 1 and 27,8. Here we present new multi-band mid-infrared images of NGC 1068 that detail the dust temperature distribution and reaffirm the original model. Combined with radio data ( J.F.G. and C.M.V.I., manuscript in preparation), our maps locate the central engine that is below the previously reported ring and obscured by a thick, nearly edge-on disk, as predicted by the unified model. We also identify emission from polar flows and absorbing dust that is mineralogically distinct from that towards the Milky Way centre.
Published: 2022
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3. Piston Reconstruction Experiment (P-REx) – II. Off-line performance evaluation with VLTI/GRAVITY

Author: Saavidra Perera, Jörg-Uwe Pott, Julien Woillez, Martin Kulas, Wolfgang Brandner, Sylvestre Lacour, and Felix Widmann
Subjects: Space and Planetary Science, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, Astronomy and Astrophysics, Astrophysics::Earth and Planetary Astrophysics
Abstract: For sensitive optical interferometry, it is crucial to control the evolution of the optical path difference (OPD) of the wavefront between the individual telescopes of the array. The OPD between a pair of telescopes is induced by differential optical properties such as atmospheric refraction, telescope alignment, etc. This has classically been measured using a fringe tracker that provides corrections to a piston actuator to account for this difference. An auxiliary method, known as the Piston Reconstruction Experiment (P-REx), has been developed to measure the OPD, or differential ‘piston’ of the wavefront, induced by the atmosphere at each telescope. Previously, this method was outlined and results obtained from Large Binocular Telescope adaptive optics data for a single telescope aperture were presented. P-REx has now been applied off-line to previously acquired Very Large Telescope Intereferometer (VLTI)’s GRAVITY Coudé Infrared Adaptive Optics wavefront sensing data to estimate the atmospheric OPD for the six baselines. Comparisons with the OPD obtained from the VLTI GRAVITY fringe tracker were made. The results indicate that the telescope and instrumental noise of the combined VLTI and GRAVITY systems dominates over the atmospheric turbulence contributions. However, good agreement between simulated and on-sky P-REx data indicates that if the telescope and instrumental noise was reduced to atmospheric piston noise levels, P-REx has the potential to reduce the OPD root mean square of piston turbulence by up to a factor of 10 for frequencies down to 1 Hz. In such conditions, P-REx will assist in pushing the sensitivity limits of optical fringe tracking with long baseline interferometers.
Published: 2022

4. VLTI status update

Author: Xavier Haubois, Antoine Mérand, Roberto Abuter, Juan Pablo Araneda, Fuyan Bian, Pierre Bourget, Paul Bristow, Pablo Burgos, Françoise Delplancke-Ströbele, Roderick Dembet, Juan Pablo Gil, Andreas Glindemann, Frédéric Gonté, Patricia Guajardo, Norbert Hubin, Christian Hummel, Heidi H. Korhonen, Aaron Labdon, Johann Kolb, Johan Kosmalski, Sylvestre Lacour, Claudia Paladini, Laurent Pallanca, Luca Pasquini, Isabelle Percheron, Miguel Riquelme, Thomas Rivinius, Eleonora Sani, Linda Schmidtobreick, Peter Scicluna, Markus Schoeller, Nicolas Schuhler, Konrad R. W. Tristram, Markus Wittkowski, Julien Woillez, and Gérard Zins
Published: 2022

5. GRAVITY+ Wide: towards hundreds of z ~ 2 AGN

Author: Antonia Drescher, Maximilian Fabricius, Taro Shimizu, Julien Woillez, Pierre Bourget, Felix Widmann, Jinyi Shangguan, Christian Straubmeier, Matthew Horrobin, Nicolas Schuhler, Frank Eisenhauer, Frederic Gonté, Stefan Gillessen, Thomas Ott, Guy Perrin, Thibaut Paumard, Wolfgang Brandner, Laura Kreidberg, Karine Perraut, Jean-Baptiste Le Bouquin, Paulo J. V. Garcia, Sebastian Hoenig, Denis Defrère, Guillaume Bourdarot, Helmut Feuchtgruber, Reinhard Genzel, Michael Hartl, Frank Haussmann, Dieter Lutz, Nikhil More, Christian Rau, Jonas Sauter, Sinem Uysal, Patrick Wessely, Ekkehard Wieprecht, Lukas Wimmer, and Senol Yazici
Published: 2022

6. Digging a dark hole in GRAVITY: towards Jupiter-like observations at the astronomical unit scale

Author: Nicolas Pourré, Jean-Baptiste Le Bouquin, Julien Woillez, Alexis Carlotti, Lucie Leboulleux, Karine Perraut, and Sylvestre Lacour
Published: 2022

7. Measuring and compensating vibrations at the VLTI: MANHATTAN-II self-intrinsic noise and hardware extension

Author: Azzurra Bigioli, Benjamin Courtney-Barrer, Roberto Abuter, Frank Eisenhauer, Frederic Gonte, Romain Laugier, Gert Raskin, Miguel Riquelme, Muhammad Salman, Nicolas Schuhler, Julien Woillez, Denis Defrère, Merand, A, Sallum, S, and Sanchez-Bermudez, J
Subjects: Technology, Science & Technology, Manhattan-II, GRAVITY, VLTI vibrations, Physical Sciences, Telescope vibrations, OPD residuals, Optics, accelerometer self-noise, Astronomy & Astrophysics, Instruments & Instrumentation
Abstract: ispartof: OPTICAL AND INFRARED INTERFEROMETRY AND IMAGING VIII vol:12183 ispartof: Conference on Optical and Infrared Interferometry and Imaging VIII Part of SPIE Astronomical Telescopes and Instrumentation Conference location:CANADA, Montreal date:17 Jul - 22 Jul 2022 status: published
Published: 2022

8. STELLIM: a Stellar Imager at VLTI

Author: Xavier Haubois, Nicolas Schuhler, Pierre Bourget, Julien Woillez, and Nick Cvetojevic
Published: 2022

9. L-band nulling interferometry at the VLTI with Asgard/Hi-5: status and plans

Author: Denis Defrère, Azzurra Bigioli, Colin Dandumont, Germain Garreau, Romain Laugier, Marc-Antoine Martinod, Olivier Absil, Jean-Philippe Berger, Emilie Bouzerand, Benjamin Courtney-Barrer, Alexandre Emsenhuber, Steve Ertel, Jonathan Gagne, Adrian M. Glauser, Simon Gross, Michael J. Ireland, Harry-Dean Kenchington Goldsmith, Jacques Kluska, Stefan Kraus, Lucas Labadie, Victor Laborde, Alain Léger, Jarron Leisenring, Jérôme Loicq, Guillermo Martin, Johan Morren, Alexis Matter, Alexandra Mazzoli, Kwinten Missiaen, Salman Muhammad, Marc Ollivier, Gert Raskin, Hélène Rousseau, Ahmed Sanny, Simon Verlinden, Bart Vandenbussche, Julien Woillez, Merand, A, Sallum, S, and Sanchez-Bermudez, J
Subjects: Technology, Science & Technology, high contrast imaging, optical fibers, exozodiacal disks, FOS: Physical sciences, CONSTRAINTS, Optics, DUST, Astronomy & Astrophysics, VLTI, long baseline interferometry, exoplanets, Physical Sciences, Nulling interferometry, DISCS, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Instruments & Instrumentation, high angular resolution
Abstract: Hi-5 is the L'-band (3.5-4.0 $\mu$m) high-contrast imager of Asgard, an instrument suite in preparation for the visitor focus of the VLTI. The system is optimized for high-contrast and high-sensitivity imaging within the diffraction limit of a single UT/AT telescope. It is designed as a double-Bracewell nulling instrument producing spectrally-dispersed (R=20, 400, or 2000) complementary nulling outputs and simultaneous photometric outputs for self-calibration purposes. In this paper, we present an update of the project with a particular focus on the overall architecture, opto-mechanical design of the warm and cold optics, injection system, and development of the photonic beam combiner. The key science projects are to survey (i) nearby young planetary systems near the snow line, where most giant planets are expected to be formed, and (ii) nearby main sequence stars near the habitable zone where exozodiacal dust that may hinder the detection of Earth-like planets. We present an update of the expected instrumental performance based on full end-to-end simulations using the new GRAVITY+ specifications of the VLTI and the latest planet formation models., Comment: 16 pages, 9 figures, SPIE 2022 "Astronomical Telescopes and Instrumentation" manuscript 12183-16
Published: 2022

10. The GRAVITY+ adaptive optics testbench: a laboratory adaptive optics integration bench that reproduces an UT Coudé focus

Author: Florentin Millour, Philippe Bério, Stéphane Lagarde, Sylvie Robbe-Dubois, Carole Gouvret, Olivier Lai, Fatmé Allouche, Christophe Bailet, Olivier Boebion, Marcel Carbillet, Aurélie Marcotto, Alain Spang, Paul Girard, Nicolas Mauclert, Jean-Baptiste Lebouquin, Thibaut Paumard, Férréol Soulez, Julien Woillez, Nikhil More, Frank Eisenhauer, Christian Straubmeier, Laura Kreidberg, Paulo J. V. Garcia, and Sebastian Hoenig
Published: 2022

11. Asgard/NOTT: L-band nulling interferometry at the VLTI

Author: Romain Laugier, Denis Defrère, Julien Woillez, Benjamin Courtney-Barrer, Felix A. Dannert, Alexis Matter, Colin Dandumont, Simon Gross, Olivier Absil, Azzurra Bigioli, Germain Garreau, Lucas Labadie, Jérôme Loicq, Marc-Antoine Martinod, Alexandra Mazzoli, Gert Raskin, and Ahmed Sanny
Subjects: interferometric, techniques: high angular resolution, methods: data analysis, methods: statistical [techniques], methods: statistical, techniques: interferometric, Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: Context. NOTT (formerly Hi-5) is a new high-contrast L′ band (3.5-4.0 μm) beam combiner for the VLTI designed with an ambitious aim to be sensitive to young giant exoplanets down to 5 mas separation around nearby stars. The performance of nulling interferometers in these wavelengths is affected both by fundamental noise from the background and contributions of instrumental noise. This motivates the development of end-to-end simulations to optimize these instruments. Aims. The aim of this study is to enable a performance evaluation of NOTT and inform the design of such instruments with current and future infrastructures in mind, taking into account the different sources of noise and their correlation. Methods. SCIFYsim is an end-to-end simulator for single-mode-filtered beam combiners, with an emphasis on nulling interferometers. We use it to compute a covariance matrix of the errors. We then use statistical detection tests based on likelihood ratios to compute compound detection limits for the instrument. Results. With the current assumptions as to the performance of the wavefront correction systems, the errors are dominated by correlated instrumental errors down to stars of magnitude 6-7 in the L band, beyond which thermal background from the telescopes and relay system becomes dominant. Conclusions. SCIFYsim is suited to anticipating some of the challenges of design, tuning, operation, and signal processing for integrated-optics beam combiners. The detection limits found for this early version of NOTT simulation with the unit telescopes are compatible with detections at contrasts up to 105 in the L band at separations of 5-80 mas around bright stars., Astronomy & Astrophysics, 671, ISSN:0004-6361, ISSN:1432-0746
Published: 2023

12. GRAVITY faint: reducing noise sources in GRAVITY$^+$ with a fast metrology attenuation system

Author: Felix Widmann, Stefan Gillessen, Thomas Ott, Taro Shimizu, Frank Eisenhauer, Maximilian Fabricius, Julien Woillez, Frédéric Gonté, Matthew Horrobin, Jingyi Shangguan, Senol Yazici, Guy Perrin, Thibaut Paumard, Wolfgang Brandner, Laura Kreidberg, Christian Straubmeier, Karin Perraut, Jean-Baptiste Le Bouquin, Paulo Garcia, Sebastian Hönig, Denis Defrère, Guillaume Bourdarot, Antonia Drescher, Helmut Feuchtgruber, Reinhard Genzel, Michael Hartl, Dieter Lutz, Nikhil More, Christian Rau, Sinem Uysal, Ekkehard Wieprecht, Merand, A, Sallum, S, and Sanchez-Bermudez, J
Subjects: Technology, Science & Technology, FOS: Physical sciences, Optics, Astronomy & Astrophysics, interferometry, near-infrared, VLTI, GRAVITY, noise-suppression, Physical Sciences, Astrophysics - Instrumentation and Methods for Astrophysics, Instruments & Instrumentation, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: With the upgrade from GRAVITY to GRAVITY$^+$ the instrument will evolve into an all-sky interferometer that can observe faint targets, such as high redshift AGN. Observing the faintest targets requires reducing the noise sources in GRAVITY as much as possible. The dominant noise source, especially in the blue part of the spectrum, is the backscattering of the metrology laser light onto the detector. To reduce this noise we introduce two new metrology modes. With a combination of small hardware changes and software adaptations, we can dim the metrology laser during the observation without losing the phase referencing. For single beam targets, we can even turn off the metrology laser for the maximum SNR on the detector. These changes lead to an SNR improvement of over a factor of two averaged over the whole spectrum and up to a factor of eight in the part of the spectrum currently dominated by laser noise., Comment: Proceeding of SPIE Astronomical Telescopes + Instrumentation 2022
Published: 2022
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13. A geometric distance to the supermassive black Hole of NGC 3783

Author: N. M. Förster Schreiber, M. L. Bolzer, Pierre-Olivier Petrucci, E. Sturm, Jason Dexter, Thibaut Paumard, Florentin Millour, Christopher A. Onken, Christian Straubmeier, Sebastian F. Hönig, Daniel Rouan, Makoto Kishimoto, Reinhard Genzel, Yann Clénet, P. T. de Zeeuw, Julien Woillez, Ric Davies, D. Kaltenbrunner, António Amorim, A. Drescher, Jinyi Shangguan, S. von Fellenberg, D. Gratadour, Misty C. Bentz, Linda J. Tacconi, J. Stadler, Karine Perraut, Felix Widmann, P. Vermot, Amiel Sternberg, Thomas Ott, Paulo J. V. Garcia, Rachel Street, Wolfgang Brandner, Odele Straub, Dieter Lutz, Hagai Netzer, Mercedes Prieto, Taro Shimizu, Stefan Gillessen, Konrad R. W. Tristram, Oliver Pfuhl, M. Bauböck, Frank Eisenhauer, Andreas Eckart, Guy Perrin, Sylvestre Lacour, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), 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), Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and GRAVITY
Subjects: Length scale, Gravity (chemistry), Cosmology and Nongalactic Astrophysics (astro-ph.CO), Galaxies: Seyfert, Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, symbols.namesake, Angular diameter, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Galaxies: nuclei, Physics, Supermassive black hole, Distance scale, Quasars: individual: NGC 3783, Astronomy and Astrophysics, Galaxies: active, Light curve, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), symbols, Reverberation mapping, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Hubble's law, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The angular size of the broad line region (BLR) of the nearby active galactic nucleus (AGN) NGC 3783 has been spatially resolved by recent observations with VLTI/GRAVITY. A reverberation mapping (RM) campaign has also recently obtained high quality light curves and measured the linear size of the BLR in a way that is complementary to the GRAVITY measurement. The size and kinematics of the BLR can be better constrained by a joint analysis that combines both GRAVITY and RM data. This, in turn, allows us to obtain the mass of the supermassive black hole in NGC3783 with an accuracy that is about a factor of two better than that inferred from GRAVITY data alone. We derive $M_\mathrm{BH}=2.54_{-0.72}^{+0.90}\times 10^7\,M_\odot$. Finally, and perhaps most notably, we are able to measure a geometric distance to NGC 3783 of $39.9^{+14.5}_{-11.9}$ Mpc. We are able to test the robustness of the BLR-based geometric distance with measurements based on the Tully-Fisher relation and other indirect methods. We find the geometric distance is consistent with other methods within their scatter. We explore the potential of BLR-based geometric distances to directly constrain the Hubble constant, $H_0$, and identify differential phase uncertainties as the current dominant limitation to the $H_0$ measurement precision for individual sources., 9 pages and 5 figures in main text, Accepted for publication in A&A
Published: 2021

14. Constraining particle acceleration in Sgr A⋆ with simultaneous GRAVITY, Spitzer, NuSTAR, and Chandra observations

Author: Wolfgang Brandner, A. Jiménez-Rosales, Mark Gurwell, Stefan Hippler, Christian Straubmeier, Th. Henning, Fiona A. Harrison, Jason Dexter, N. M. Förster Schreiber, F. Vincent, Pierre Kervella, Daryl Haggard, S. Yazici, Silvia Scheithauer, Oliver Pfuhl, Y. Dallilar, T. Taro Shimizu, Idel Waisberg, Odele Straub, K. Foster, Felix Widmann, Sera Markoff, Dieter Lutz, J.-B. Le Bouquin, M. Bauböck, Matthew Horrobin, Yann Clénet, P. T. de Zeeuw, Gabriele Ghisellini, Howard A. Smith, Frederick K. Baganoff, Daniel Stern, Thibaut Paumard, Eckhard Sturm, Ric Davies, M. Nowak, Andreas Eckart, Andreas Kaufer, Sebastian Rabien, Laurent Jocou, Paulo J. V. Garcia, Ekkehard Wieprecht, Reinhard Genzel, Jinyi Shangguan, G. Rodríguez-Coira, Patrick Lowrance, C. J. Hailey, Thomas Ott, S. Zhang, A. Drescher, G. Ponti, Giovanni G. Fazio, Steven P. Willner, S. D. von Fellenberg, Linda J. Tacconi, Maryam Habibi, H. Bonnet, Julien Woillez, V. Lapeyrère, Sylvestre Lacour, António Amorim, Erich Wiezorrek, Xavier Haubois, Guy Perrin, J. Neilsen, K. Mori, Eric Gendron, Frank Eisenhauer, G. Heißel, Pierre Léna, Joseph L. Hora, Karine Perraut, Charles F. Gammie, Feng Gao, G. Witzel, Gérard Zins, Mark Morris, André Young, Julia Stadler, Jean-Phillipe Berger, Hope Boyce, Stefan Gillessen, Lieselotte Jochum, Roberto Abuter, High Energy Astrophys. & Astropart. Phys (API, FNWI), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and 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)
Subjects: Accretion, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Electron, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Astrophysics - high energy astrophysical phenomena, law.invention, Luminosity, symbols.namesake, law, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Accretion (meteorology), Galaxy: center, 010308 nuclear & particles physics, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astronomy and Astrophysics, Black hole physics, Synchrotron, ddc, Particle acceleration, Lorentz factor, 13. Climate action, Space and Planetary Science, Accretion disks, symbols, Spectral energy distribution, Flare
Abstract: We report the time-resolved spectral analysis of a bright near-infrared and moderate X-ray flare of Sgr A*. We obtained light curves in the $M$-, $K$-, and $H$-bands in the mid- and near-infrared and in the $2-8~\mathrm{keV}$ and $2-70~\mathrm{keV}$ bands in the X-ray. The observed spectral slope in the near-infrared band is $\nu L_\nu\propto \nu^{0.5\pm0.2}$; the spectral slope observed in the X-ray band is $\nu L_\nu \propto \nu^{-0.7\pm0.5}$. We tested synchrotron and synchrotron self-Compton (SSC) scenarios. The observed near-infrared brightness and X-ray faintness, together with the observed spectral slopes, pose challenges for all models explored. We rule out a scenario in which the near-infrared emission is synchrotron emission and the X-ray emission is SSC. A one-zone model in which both the near-infrared and X-ray luminosity are produced by SSC and a model in which the luminosity stems from a cooled synchrotron spectrum can explain the flare. In order to describe the mean SED, both models require specific values of the maximum Lorentz factor $\gamma_{max}$, which however differ by roughly two orders of magnitude: the SSC model suggests that electrons are accelerated to $\gamma_{max}\sim 500$, while cooled synchrotron model requires acceleration up to $\gamma_{max}\sim5\times 10^{4}$. The SSC scenario requires electron densities of $10^{10}~\mathrm{cm^{-3}}$ much larger than typical ambient densities in the accretion flow, and thus require in an extraordinary accretion event. In contrast, assuming a source size of $1R_s$, the cooled synchrotron scenario can be realized with densities and magnetic fields comparable with the ambient accretion flow. For both models, the temporal evolution is regulated through the maximum acceleration factor $\gamma_{max}$, implying that sustained particle acceleration is required to explain at least a part of the temporal evolution of the flare., Comment: accepted for publication in Astronomy & Astrophysics; preview abstract shortened due to arXiv requirements
Published: 2021

15. VLTI-MATISSE chromatic aperture-synthesis imaging of η Carinae's stellar wind across the Brα line: Periastron passage observations in February 2020

Author: Th. Rivinius, C. M. P. Russell, A. Domiciano de Souza, Uwe Beckmann, Lucas Labadie, F. Allouche, P. Cruzalèbes, Sylvie Robbe-Dubois, Antoine Mérand, William C. Danchi, A. F. J. Moffat, Kenji Hamaguchi, Michael F. Corcoran, József Varga, Alexis Matter, Thomas I. Madura, Stephane Lagarde, Sebastian Wolf, Anthony Meilland, Walter Jaffe, Paul Bristow, T. R. Gull, Felix Bettonvil, D. A. Espinoza-Galeas, Jose H. Groh, J. C. Augereau, Carsten Dominik, W. J. de Wit, Markus Schöller, J. Leftley, V. Hocdé, Uwe Graser, R. van Boekel, F. Navarete, L. Klarmann, K. Ohnaka, Leonard Burtscher, Th. Henning, Karl-Heinz Hofmann, Augusto Damineli, Ian R. Stevens, C. Connot, Klaus Meisenheimer, Stefan Kraus, Patrick W. Morris, G. Yoffe, Michiel R. Hogerheijde, Romain Petrov, Ph. Berio, M. Heininger, Henrik Hartman, J. W. Isbell, Markus Wittkowski, Eric Pantin, E. Kokoulina, J. Drevon, Julien Woillez, L. B. F. M. Waters, E. Nußbaum, Dieter Schertl, Bruno Lopez, Alexander Kreplin, Gerd Weigelt, Florentin Millour, D. J. Hillier, J. Hron, M. Lehmitz, V. Gámez Rosas, J. Sanchez-Bermudez, Noel D. Richardson, C. A. Hummel, Claudia Paladini, Andrea Mehner, Farrokh Vakili, Andreas Glindemann, P. Antonelli, C. Leinert, Gérard Zins, Philippe Stee, and Low Energy Astrophysics (API, FNWI)
Subjects: Interferometric, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, Continuum (design consultancy), individual: eta Carinae [stars], Context (language use), Outflows, Individual, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Winds, 01 natural sciences, Spectral line, outflows, Mass-Loss, general [binaries], massive [stars], Astronomi, astrofysik och kosmologi, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astronomy, Astrophysics and Cosmology, winds [stars], General, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Line (formation), O-type star, Physics, 010308 nuclear & particles physics, Binaries, Astronomy and Astrophysics, mass-loss [stars], Radius, Stars, Techniques, interferometric [techniques], Luminous blue variable, 13. Climate action, Space and Planetary Science, Massive, Astrophysics::Earth and Planetary Astrophysics, η Carinae
Abstract: Context. Eta Carinae is a highly eccentric, massive binary system (semimajor axis ~15.5 au) with powerful stellar winds and a phase-dependent wind-wind collision (WWC) zone. The primary star, η Car A, is a luminous blue variable (LBV); the secondary, η Car B, is a Wolf-Rayet or O star with a faster but less dense wind. Aperture-synthesis imaging allows us to study the mass loss from the enigmatic LBV η Car. Understanding LBVs is a crucial step toward improving our knowledge about massive stars and their evolution. Aims. Our aim is to study the intensity distribution and kinematics of η Car’s WWC zone. Methods. Using the VLTI-MATISSE mid-infrared interferometry instrument, we perform Brα imaging of η Car’s distorted wind. Results. We present the first VLTI-MATISSE aperture-synthesis images of η Car A’s stellar windin several spectral channels distributed across the Brα 4.052 μm line (spectral resolving power R ~ 960). Our observations were performed close to periastron passage in February 2020 (orbital phase ~ 14.0022). The reconstructed iso-velocity images show the dependence of the primary stellar wind on wavelength or line-of-sight (LOS) velocity with a spatial resolution of 6 mas (~14 au). The radius of the faintest outer wind regions is ~26 mas (~60 au). At several negative LOS velocities, the primary stellar wind is less extended to the northwest than in other directions. This asymmetry is most likely caused by the WWC. Therefore, we see both the velocity field of the undisturbed primary wind and the WWC cavity. In continuum spectral channels, the primary star wind is more compact than in line channels. A fit of the observed continuum visibilities with the visibilities of a stellar wind CMFGEN model (CMFGEN is an atmosphere code developed to model the spectra of a variety of objects) provides a full width at half maximum fit diameter of the primary stellar wind of 2.84 ± 0.06 mas (6.54 ± 0.14 au). We comparethe derived intensity distributions with the CMFGEN stellar wind model and hydrodynamic WWC models.
Published: 2021

16. First MATISSE L-band observations of HD 179218

Author: Dieter Schertl, Th. Henning, Gerd Weigelt, Florentin Millour, József Varga, Stephane Lagarde, J. Hron, Walter Jaffe, J. Leftley, Karl-Heinz Hofmann, L. Klarmann, G. Yoffe, A. Soulain, M. Heininger, V. Hocdé, Marco Delbo, Felix C. M. Bettonvil, Paul Bristow, Anthony Meilland, Uwe Beckmann, F. Allouche, A. Bensberg, M. Lehmitz, J. C. Augereau, C. A. Hummel, Lucas Labadie, Gérard Zins, Philippe Berio, Uwe Graser, Farrokh Vakili, P. Antonelli, Markus Wittkowski, Pierre Cruzalèbes, Nathalie Ysard, C. Leinert, Carsten Dominik, L. B. F. M. Waters, Claudia Paladini, Isabelle Percheron, J. Duprat, Anthony P. Jones, Michiel R. Hogerheijde, E. Habart, Sylvie Robbe-Dubois, J. W. Isbell, Eric Pantin, R. van Boekel, Klaus Meisenheimer, Julien Woillez, Bruno Lopez, Alexis Matter, Péter Ábrahám, E. Kokoulina, Romain Petrov, V. Gámez Rosas, Emmanuel Dartois, Ph. Stee, Sebastian Wolf, J. Drevon, M. Dannhoff, William C. Danchi, Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Low Energy Astrophysics (API, FNWI), and Ysard, Nathalie
Subjects: Interferometric, 010504 meteorology & atmospheric sciences, Infrared, Astronomy, Continuum (design consultancy), chemistry.chemical_element, FOS: Physical sciences, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Spectral resolution, General, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Very Large Telescope, Protoplanetary Disks, Astronomy and Astrophysics, Techniques, Astrophysics - Solar and Stellar Astrophysics, Amorphous carbon, chemistry, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Circumstellar Matter, Spectral energy distribution, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Astrophysics::Earth and Planetary Astrophysics, [SDU.ASTR.GA] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Astrophysics - Solar and Stellar Astrophysic, Carbon, Astrophysics - Earth and Planetary Astrophysics
Abstract: Context. Carbon is one of the most abundant components in the Universe. While silicates have been the main focus of solid phase studies in protoplanetary discs (PPDs), little is known about the solid carbon content especially in the planet-forming regions (~0.1–10 au). Fortunately, several refractory carbonaceous species present C-H bonds (such as hydrogenated nano-diamond and amorphous carbon as well as polycyclic aromatic hydrocarbons), which generate infrared (IR) features that can be used to trace the solid carbon reservoirs. The new mid-IR instrument MATISSE, installed at the Very Large Telescope Interferometer (VLTI), can spatially resolve the inner regions (~1–10 au) of PPDs and locate, down to the au-scale, the emission coming from carbon grains. Aims. Our aim is to provide a consistent view on the radial structure, down to the au-scale, as well as basic physical properties and the nature of the material responsible for the IR continuum emission in the inner disk region around HD 179218. Methods. We implemented a temperature-gradient model to interpret the disk IR continuum emission, based on a multiwavelength dataset comprising a broadband spectral energy distribution and VLTI H-, L-, and N-bands interferometric data obtained in low spectral resolution. Then, we added a ring-like component, representing the carbonaceous L-band features-emitting region, to assess its detectability in future higher spectral resolution observations employing mid-IR interferometry. Results. Our temperature-gradient model can consistently reproduce our dataset. We confirmed a spatially extended inner 10 au emission in H- and L-bands, with a homogeneously high temperature (~1700 K), which we associate with the presence of stochastically heated nano-grains. On the other hand, the N-band emitting region presents a ring-like geometry that starts at about 10 au with a temperature of 400 K. Moreover, the existing low resolution MATISSE data exclude the presence of aromatic carbon grains (i.e., producing the 3.3 μm feature) in close proximity tothe star (≲1 au). Future medium spectral resolution MATISSE data will confirm their presence at larger distances. Conclusions. Our best-fit model demonstrates the presence of two separated dust populations: nano-grains that dominate the near- to mid-IR emission in the inner 10 au region and larger grains that dominate the emission outward. The presence of such nano-grains in the highly irradiated inner 10 au region of HD 179218 requires a replenishment process. Considering the expected lifetime of carbon nano-grains from The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS model), the estimated disk accretion inflow of HD 179218 could significantly contribute to feed the inner 10 au region in nano-grains.Moreover, we also expect a local regeneration of those nano-grains by the photo-fragmentation of larger aggregates.
Published: 2021

17. Astrometric Interferometry

Author: Michael J. Ireland and Julien Woillez
Published: 2021

18. Thermal imaging of dust hiding the black hole in NGC 1068

Author: Violeta, Gámez Rosas, Jacob W, Isbell, Walter, Jaffe, Romain G, Petrov, James H, Leftley, Karl-Heinz, Hofmann, Florentin, Millour, Leonard, Burtscher, Klaus, Meisenheimer, Anthony, Meilland, Laurens B F M, Waters, Bruno, Lopez, Stéphane, Lagarde, Gerd, Weigelt, Philippe, Berio, Fatme, Allouche, Sylvie, Robbe-Dubois, Pierre, Cruzalèbes, Felix, Bettonvil, Thomas, Henning, Jean-Charles, Augereau, Pierre, Antonelli, Udo, Beckmann, Roy, van Boekel, Philippe, Bendjoya, William C, Danchi, Carsten, Dominik, Julien, Drevon, Jack F, Gallimore, Uwe, Graser, Matthias, Heininger, Vincent, Hocdé, Michiel, Hogerheijde, Josef, Hron, Caterina M V, Impellizzeri, Lucia, Klarmann, Elena, Kokoulina, Lucas, Labadie, Michael, Lehmitz, Alexis, Matter, Claudia, Paladini, Eric, Pantin, Jörg-Uwe, Pott, Dieter, Schertl, Anthony, Soulain, Philippe, Stee, Konrad, Tristram, Jozsef, Varga, Julien, Woillez, Sebastian, Wolf, Gideon, Yoffe, and Gerard, Zins
Abstract: In the widely accepted 'unified model'
Published: 2021

19. The asymmetric inner disk of the Herbig Ae star HD 163296 in the eyes of VLTI/MATISSE: evidence for a vortex?

Author: William C. Danchi, Luca Pasquini, Lars Venema, Leonard Burtscher, Josef Hron, Markus Wittkowski, J. Beltran, H. Méheut, Antoine Mérand, Sylvie Robbe-Dubois, A. Jaskó, Th. Henning, Farrokh Vakili, F. Guitton, Anthony Meilland, J. Vinther, Carsten Dominik, A. Gabasch, S. Rousseau, E. Kokoulina, M. Ebert, P. Antonelli, J.-U. Pott, N. Tromp, J.-L. Lizon, F. Rigal, J. Kragt, Markus Schöller, Ronald Roelfsema, Romain Petrov, L. Klarmann, P. Guajardo, Karl Heinz Hofmann, R. Frahm, Klaus Meisenheimer, Alexis Matter, F. Wrhel, Nicolas Schuhler, Gerd Jakob, Gerd Weigelt, Ph. Stee, Laurent Pallanca, A. Marcotto, Pierre Cruzalèbes, A. Chelli, I. Percheron, J. C. González Herrera, Andreas Glindemann, Claudia Paladini, Jean-Michel Clausse, M. de Haan, Eddy Elswijk, K. Meixner, Felix Bettonvil, S. Morel, R. Castillo, Uwe Graser, E. Nußbaum, Paul Bristow, Péter Ábrahám, J. W. Isbell, Eric Pantin, T. Maurer, R. ter Horst, Bruno Lopez, R. van Boekel, T. Adler, A. van Duin, L. Mosoni, Alexandre Gallenne, Udo Neumann, Ralf Conzelmann, Jean-Charles Augereau, Yves Bresson, Ramón Navarro, Norbert Hubin, M. Accardo, E. Garces, F. Allouche, Julien Woillez, Th. Rivinius, Y. Fantei, S. Abadie, A. Ridinger, Derek Ives, F. Donnan, G. Bazin, Ralf Klein, Udo Beckmann, M. Mellein, Roberto Abuter, Eszter Pozna, Sebastian Wolf, Tibor Agócs, J. Meisner, D. Schertl, L. Mohr, Marcelo Lopez, L. Jochum, Ralf-Rainer Rohloff, C. Connot, A. Soulain, Claudia Cid, W. Laun, C. Stephan, M. Heininger, R. Brast, V. Gámez Rosas, W. Boland, Michiel R. Hogerheijde, Ph. Berio, Marco Delbo, Christoph Leinert, S. Kuindersma, L. Labadie, A. Böhm, Xavier Haubois, N. Mauclert, Leander Mehrgan, F. Y. J. Gonté, M. Schuil, L. B. F. M. Waters, G. Zins, P. Bourget, R. S. Le Poole, P. Girard, M. Riquelme, József Varga, Florentin Millour, Stephane Lagarde, Walter Jaffe, R. Huerta, M. Lehmitz, G. Kroes, G. Yoffe, C. Bailet, foreign laboratories (FL), CERN [Genève], Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Max-Planck-Institut für Radioastronomie (MPIFR), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Anton Pannenkoek Institute for Astronomy [University of Amsterdam], Max Planck Institute for Astronomy (MPIA), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Low Energy Astrophysics (API, FNWI), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de la Côte d'Azur (OCA), and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Brightness, Interferometric, Astronomy, media_common.quotation_subject, Astronomical unit, [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, Asymmetry, Instability, 0103 physical sciences, Surface brightness, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, media_common, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Pre-Main Sequence, Protoplanetary Disks, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Research Programm of Institute for Mathematics, Astrophysics and Particle Physics, 010308 nuclear & particles physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, Position angle, Stars, Techniques, Vortex, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Azimuth, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Circumstellar Matter, Astrophysics::Earth and Planetary Astrophysics, Infrared, Astrophysics - Earth and Planetary Astrophysics
Abstract: Context. The inner few au region of planet-forming disks is a complex environment. High angular resolution observations have a key role in understanding the disk structure and the dynamical processes at work. Aims. In this study we aim to characterize the mid-infrared brightness distribution of the inner disk of the young intermediate-mass star HD 163296, from VLTI/MATISSE observations. Methods. We use geometric models to fit the data. Our models include a smoothed ring, a flat disk with inner cavity, and a 2D Gaussian. The models can account for disk inclination and for azimuthal asymmetries as well. We also perform numerical hydro-dynamical simulations of the inner edge of the disk. Results. Our modeling reveals a significant brightness asymmetry in the L-band disk emission. The brightness maximum of the asymmetry is located at the NW part of the disk image, nearly at the position angle of the semimajor axis. The surface brightness ratio in the azimuthal variation is $3.5 \pm 0.2$. Comparing our result on the location of the asymmetry with other interferometric measurements, we confirm that the morphology of the $r, accepted for publication in A&A
Published: 2021

20. Mid-infrared circumstellar emission of the long-period Cepheid l Carinae resolved with VLTI/MATISSE

Author: M. Schuil, G. Zins, Y. Fantei, Udo Beckmann, Péter Ábrahám, Anthony Meilland, K. Shabun, Philippe Stee, Farrokh Vakili, Ronald Roelfsema, A. Böhm, Andrea Chiavassa, G. Niccolini, L. Labadie, L. Mosoni, M. Riquelme, Alexandre Gallenne, P. Antonelli, R. Frahm, J.-L. Lizon, Markus Schöller, Ralf-Rainer Rohloff, Florentin Millour, Jean-Michel Clausse, Udo Neumann, F. Wrhel, M. de Haan, J. Meisner, Leonard Burtscher, R. Huerta, F. Allouche, Luca Pasquini, E. Garces, Pierre Cruzalèbes, Nicolas Nardetto, S. Morel, Behnam Javanmardi, P. Bourget, L. Jochum, A. Ridinger, R. S. Le Poole, Th. Rivinius, Bruno Lopez, V. Hocdé, Marco Delbo, I. Percheron, P. Girard, J. C. González Herrera, M. Accardo, G. Bazin, Karl Heinz Hofmann, Laszlo Szabados, J. W. Isbell, Eric Pantin, Jaime Alonso, Josef Hron, D. Schertl, Eszter Pozna, L. Klarmann, Th. Henning, S. Rousseau, C. Connot, E. Nußbaum, Eddy Elswijk, Louise Breuval, Antoine Mérand, R. van Boekel, E. Kokoulina, Leander Mehrgan, József Varga, Roberto Abuter, Markus Wittkowski, T. Adler, E. Lagadec, Claudia Paladini, M. Heininger, F. Guitton, Nicolas Schuhler, W. Laun, Romain Petrov, A. Jaskó, S. Abadie, R. ter Horst, Stephane Lagarde, R. Brast, F. Y. J. Gonté, Norbert Hubin, William C. Danchi, V. Gámez Rosas, A. Soulain, Walter Jaffe, Pierre Kervella, W. Boland, Ramón Navarro, Michiel R. Hogerheijde, Julien Woillez, K. Meixner, Felix Bettonvil, S. Borgniet, J. Beltran, Uwe Graser, Ph. Berio, Ralf Klein, J. Idserda, M. Lopez, Klaus Meisenheimer, Andreas Glindemann, J.-U. Pott, H. Hanenburg, Lars Venema, Sylvie Robbe-Dubois, Alexis Matter, Tibor Agócs, R. Buter, M. Ebert, Carsten Dominik, P. Guajardo, Laurent Pallanca, A. Marcotto, R. Waters, A. Gabasch, R. Castillo, M. Lehmitz, Jean-Charles Augereau, Derek Ives, Yves Bresson, S. Kuindersma, A. Glazenborg, Claudia Cid, C. Stephan, Sebastian Wolf, L. Mohr, J. Kragt, Christoph Leinert, F. Rigal, N. Tromp, Xavier Haubois, N. Mauclert, Gerd Jakob, Gerd Weigelt, J. Vinther, A. Chelli, C. Bailet, Paul Bristow, A. Domiciano de Souza, T. Maurer, A. van Duin, Ralf Conzelmann, M. Mellein, G. Kroes, G. Yoffe, T. Phan Duc, Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Lagrange, Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS., European Southern Observatory (ESO), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Radioastronomie (MPIFR), Max Planck Institute for Astronomy (MPIA), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Low Energy Astrophysics (API, FNWI)
Subjects: Infrared, Cepheid variable, Astronomy, Astrophysics - astrophysics of galaxies, Flux, FOS: Physical sciences, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Astrophysics - solar and stellar astrophysics, 010309 optics, Spitzer Space Telescope, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Spectroscopy, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Research Programm of Institute for Mathematics, Astrophysics and Particle Physics, Stars: variables: Cepheids, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, Circumstellar matter, Infrared: stars, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Stars, Wavelength, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Instrumentation: interferometers, Astrophysics of Galaxies (astro-ph.GA), Stars: atmospheres, Astrophysics::Earth and Planetary Astrophysics
Abstract: The nature of circumstellar envelopes (CSE) around Cepheids is still a matter of debate. The physical origin of their infrared (IR) excess could be either a shell of ionized gas, or a dust envelope, or both. This study aims at constraining the geometry and the IR excess of the environment of the long-period Cepheid $\ell$ Car (P=35.5 days) at mid-IR wavelengths to understand its physical nature. We first use photometric observations in various bands and Spitzer Space Telescope spectroscopy to constrain the IR excess of $\ell$ Car. Then, we analyze the VLTI/MATISSE measurements at a specific phase of observation, in order to determine the flux contribution, the size and shape of the environment of the star in the L band. We finally test the hypothesis of a shell of ionized gas in order to model the IR excess. We report the first detection in the L band of a centro-symmetric extended emission around l Car, of about 1.7$R_\star$ in FWHM, producing an excess of about 7.0\% in this band. In the N band, there is no clear evidence for dust emission from VLTI/MATISSE correlated flux and Spitzer data. On the other side, the modeled shell of ionized gas implies a more compact CSE ($1.13\pm0.02\,R_\star$) and fainter (IR excess of 1\% in the L band). We provide new evidences for a compact CSE of $\ell$ Car and we demonstrate the capabilities of VLTI/MATISSE for determining common properties of CSEs. While the compact CSE of $\ell$ Car is probably of gaseous nature, the tested model of a shell of ionized gas is not able to simultaneously reproduce the IR excess and the interferometric observations. Further Galactic Cepheids observations with VLTI/MATISSE are necessary for determining the properties of CSEs, which may also depend on both the pulsation period and the evolutionary state of the stars., Comment: 13 pages, 8 figures, accepted in Astronomy and Astrophysics
Published: 2021

21. Detection of faint stars near Sagittarius A* with GRAVITY

Author: Christian Straubmeier, Stefan Hippler, Th. Henning, Feng Gao, Gérard Zins, Maryam Habibi, Linda J. Tacconi, Oliver Pfuhl, V. Lapeyrère, Xavier Haubois, Guy Perrin, A. Jiménez-Rosales, Felix Widmann, G. Heißel, António Amorim, Stefan Gillessen, Yann Clénet, P. T. de Zeeuw, H. Bonnet, Jason Dexter, Paulo J. V. Garcia, Julien Woillez, Ric Davies, Lieselotte Jochum, Eric Gendron, G. Rodríguez-Coira, Eckhard Sturm, Laurent Jocou, Jinyi Shangguan, S. Yazici, T. Taro Shimizu, Thibaut Paumard, M. Nowak, M. Bauböck, Karine Perraut, Reinhard Genzel, N. M. Förster Schreiber, Wolfgang Brandner, Matthew Horrobin, Julia Stadler, Thomas Ott, Idel Waisberg, A. Drescher, S. von Fellenberg, Sebastian Rabien, Ekkehard Wieprecht, F. Vincent, Pierre Kervella, Jean-Philippe Berger, Odele Straub, Dieter Lutz, J.-B. Le Bouquin, Sylvestre Lacour, Silvia Scheithauer, Y. Dallilar, Andreas Kaufer, Frank Eisenhauer, Pierre Léna, Erich Wiezorrek, Roberto Abuter, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), 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), Observatoire de Paris - Site de Meudon (OBSPM), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and GRAVITY
Subjects: Astrophysics - instrumentation and methods for astrophysics, Stars: imaging, Proper motion, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics - astrophysics of galaxies, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Supermassive black hole, Galaxy: center, 010308 nuclear & particles physics, Galactic Center, Astronomy and Astrophysics, Infrared: stars, Stars, Sagittarius A, 13. Climate action, Space and Planetary Science, Magnitude (astronomy), Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Radio astronomy, Gravitational redshift
Abstract: International audience; The spin of the supermassive black hole that resides at the Galactic Center can, in principle, be measured by accurate measurements of the orbits of stars that are much closer to Sgr A* than S2, the orbit of which recently provided the measurement of the gravitational redshift and the Schwarzschild precession. The GRAVITY near-infrared interferometric instrument combining the four 8m telescopes of the VLT provides a spatial resolution of 2–4 mas, breaking the confusion barrier for adaptive-optics-assisted imaging with a single 8–10m telescope. We used GRAVITY to observe Sgr A* over a period of six months in 2019 and employed interferometric reconstruction methods developed in radio astronomy to search for faint objects near Sgr A*. This revealed a slowly moving star of magnitude 18.9 in the K-band within 30 mas of Sgr A*. The position and proper motion of the star are consistent with the previously known star S62, which is at a substantially greater physical distance, but in projection passes close to Sgr A*. Observations in August and September 2019 detected S29 easily, with K-magnitude of 16.6, at approximately 130 mas from Sgr A*. The planned upgrades of GRAVITY, and further improvements in the calibration, offer greater chances of finding stars fainter than K-magnitude of 19.Key words: Galaxy: center / stars: imaging / infrared: stars⋆ GRAVITY was developed as part of a collaboration by the Max Planck Institute for extraterrestrial Physics, LESIA of the Observatoire de Paris/Université PSL/CNRS/Sorbonne Université/Université de Paris and IPAG of Université Grenoble Alpes/CNRS, the Max Planck Institute for Astronomy, the University of Cologne, the CENTRA – Centro de Astrofisica e Gravitação, and the European Southern Observatory.⋆⋆ Corresponding authors: F. Gao, e-mail: fgao@mpe.mpg.de; T. Paumard, e-mail: thibaut.paumard@obspm.fr
Published: 2021

22. The GRAVITY Young Stellar Object survey VIII. Gas and dust faint inner rings in the hybrid disk of HD141569

Author: R. Grellmann, O. Pfuhl, V. Ganci, Eric Gendron, Feng Gao, Stefan Hippler, V. Coudé du Foresto, Guy Perrin, Gérard Rousset, Thibaut Paumard, Frederic H. Vincent, Catherine Dougados, A. Wojtczak, R. Genzel, A. Drescher, A. de Valon, Lucas Labadie, Gilles Duvert, E. F. van Dishoeck, G. Heissel, S. D. von Fellenberg, V. Lapeyrère, Mercedes E. Filho, Christian Straubmeier, Karine Perraut, Julia Stadler, Th. Henning, Paola Caselli, Felix Widmann, Z. Hubert, Stefan Gillessen, Matthew Horrobin, António Amorim, Odele Straub, R. Garcia Lopez, J.-B. Le Bouquin, L. Klarmann, Paulo J. V. Garcia, Jean-Phillipe Berger, G. Heißel, J. Sanchez-Bermudez, Andreas Eckart, Pierre Kervella, Silvia Scheithauer, Sylvestre Lacour, T. Ott, Frank Eisenhauer, Pierre Léna, T. Taro Shimizu, M. Bauböck, A. Caratti o Garatti, A. Jiménez-Rosales, Myriam Benisty, F. Eupen, Julien Woillez, Eckhard Sturm, Laurent Jocou, Wolfgang Brandner, Yann Clénet, P. T. de Zeeuw, and Jinyi Shangguan
Subjects: Physics, Protoplanetary disks, Earth and Planetary Astrophysics (astro-ph.EP), Young stellar object, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Planetary system, Stars, Infrared: planetary systems, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Techniques: interferometric, Radiative transfer, Spectral energy distribution, Astrophysics::Solar and Stellar Astrophysics, Emission spectrum, Astrophysics::Earth and Planetary Astrophysics, Spectral resolution, Stars: individual: HD 141569, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Line (formation), Astrophysics - Earth and Planetary Astrophysics
Abstract: The formation and evolution of planetary systems impact the primordial accretion disk. HD141569 is the only known pre-main sequence star characterized by a hybrid disk. Observations probed the outer-disk structure showing a complex system of rings and interferometric observations attempted to characterize its inner 5 au region, but derived limited constraints. The goal of this work was to explore with new high-resolution interferometric observations the properties of the dust and gas in the internal regions of HD141569. We observed HD141569 on mas scales with GRAVITY/VLTI in the near-infrared at low and high spectral resolution. We interpreted the visibilities and spectral energy distribution with geometrical models and radiative transfer techniques to constrain the dust emission. We analyzed the high spectral resolution quantities to investigate the properties of the Br-Gamma line emitting region. Thanks to the combination of three different epochs, GRAVITY resolves the inner dusty disk in the K band. Data modeling shows that an IR excess of about 6% is spatially resolved and that the origin of this emission is confined in a ring of material located at a radius of 1 au from the star with a width smaller than 0.3 au. The MCMax modeling suggests that this emission could originate from a small amount of QHPs, while large silicate grain models cannot reproduce at the same time the observational constraints on the properties of near-IR and mid-IR fluxes. The differential phases in the Br-Gamma line clearly show an S-shape that can be best reproduced witha gas disk in Keplerian rotation, confined within 0.09 au. This is also hinted at by the double-peaked Br-Gamma emission line shape. The modeling of the continuum and gas emission shows that the inclination and position angle of these two components are consistent with a system showing relatively coplanar rings on all scales., Comment: Accepted for publication in A&A; 25 pages, 15 figures, 5 tables
Published: 2021
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23. MOLsphere and pulsations of the Galactic Center’s red supergiant GCIRS 7 from VLTI/GRAVITY

Author: Karine Perraut, Xavier Haubois, Jason Dexter, Christian Straubmeier, Th. Henning, F. H. Vincent, Linda J. Tacconi, Eckhard Sturm, Idel Waisberg, Stefan Hippler, Guy Perrin, Vincent Lapeyrere, J. Sanchez-Bermudez, Felix Widmann, Andreas Kaufer, Thomas Ott, A. Drescher, O. Pfuhl, Julien Woillez, G. Rodríguez-Coira, Laurent Jocou, Jean-Philippe Berger, Eric Gendron, Lieselotte Jochum, Gérard Zins, S. von Fellenberg, Paulo J. V. Garcia, Sylvestre Lacour, Stefan Gillessen, M. Nowak, N. M. Förster Schreiber, Julia Stadler, Matthew Horrobin, Feng Gao, António Amorim, Frank Eisenhauer, Pierre Léna, Odele Straub, J.-B. Le Bouquin, Erich Wiezorrek, M. Habibi, Reinhard Genzel, Silvia Scheithauer, H. Bonnet, Thibaut Paumard, Pierre Kervella, A. Jiménez-Rosales, Andreas Eckart, Ekkehard Wieprecht, S. Yazici, T. Taro Shimizu, M. Bauböck, Roberto Abuter, Jinyi Shangguan, Wolfgang Brandner, Yann Clénet, P. T. de Zeeuw, 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), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Département de Chimie Moléculaire - Ingéniérie et Intéractions BioMoléculaires (DCM - I2BM), Département de Chimie Moléculaire (DCM), Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Extraterrestrische Physik (MPE), 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), Wageningen University and Research [Wageningen] (WUR), European Southern Observatory [Santiago] (ESO), European Southern Observatory (ESO), Poznan Technical University, Max Planck Institute for Astronomy (MPIA), GRAVITY Collaboration, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics [LESIA], Récepteurs nucléaires, maladies cardiovasculaires et diabète - U 1011 [RNMCD], Département de Chimie Moléculaire - Ingéniérie et Intéractions BioMoléculaires [DCM - I2BM], Max-Planck-Institut für Extraterrestrische Physik [MPE], Laboratoire d'études spatiales et d'instrumentation en astrophysique [LESIA], Wageningen University and Research [Wageningen] [WUR], European Southern Observatory [Santiago] [ESO], European Southern Observatory [ESO], Institut Européen des membranes [IEM], Institut de Planétologie et d'Astrophysique de Grenoble [IPAG], Max Planck Institute for Astronomy [MPIA], Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Universidade de Lisboa = University of Lisbon (ULISBOA), Centro de Astrofísica e Gravitação (CENTRA), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Leiden University, University of Colorado [Boulder], Universität zu Köln = University of Cologne, Max Planck Institute for Radio Astronomy, Universidade do Porto = University of Porto, University of California [Berkeley] (UC Berkeley), University of California (UC), Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), Weizmann Institute of Science [Rehovot, Israël], Sciences, EDP, Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institut Européen des membranes (IEM), and Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Galaxy: nucleus, techniques: interferometric, stars: individual: GCIRS 7, stars: fundamental parameters, supergiants, Astrophysics - astrophysics of galaxies, Extinction (astronomy), Continuum (design consultancy), FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, Astrophysics - solar and stellar astrophysics, 0103 physical sciences, Red supergiant, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, Photosphere, 010308 nuclear & particles physics, Galactic Center, Astronomy and Astrophysics, Stars, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Supergiant, [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: GCIRS 7, the brightest star in the Galactic central parsec, formed $6\pm2$ Myr ago together with dozens of massive stars in a disk orbiting the central black-hole. It has been argued that GCIRS 7 is a pulsating body, on the basis of photometric variability. We present the first medium-resolution ($R=500$), K-band spectro-interferometric observations of GCIRS 7, using the GRAVITY instrument with the four auxiliary telescopes of the ESO VLTI. We looked for variations using two epochs, namely 2017 and 2019. We find GCIRS 7 to be moderately resolved with a uniform-disk photospheric diameter of $\theta^*_\text{UD}=1.55 \pm 0.03$ mas ($R^*_\text{UD}=1368 \pm 26$ $R_\odot$) in the K-band continuum. The narrow-band uniform-disk diameter increases above 2.3 $\mu$m, with a clear correlation with the CO band heads in the spectrum. This correlation is aptly modeled by a hot ($T_\text{L}=2368\pm37$ K), geometrically thin molecular shell with a diameter of $\theta_\text{L}=1.74\pm0.03$ mas, as measured in 2017. The shell diameter increased ($\theta_\text{L}=1.89\pm0.03$ mas), while its temperature decreased ($T_\text{L}=2140\pm42$ K) in 2019. In contrast, the photospheric diameter $\theta^*_\text{UD}$ and the extinction up to the photosphere of GCIRS 7 ($A_{\mathrm{K}_\mathrm{S}}=3.18 \pm 0.16$) have the same value within uncertainties at the two epochs. In the context of previous interferometric and photo-spectrometric measurements, the GRAVITY data allow for an interpretation in terms of photospheric pulsations. The photospheric diameter measured in 2017 and 2019 is significantly larger than previously reported using the PIONIER instrument ($\theta_*=1.076 \pm 0.093$ mas in 2013 in the H band). The parameters of the photosphere and molecular shell of GCIRS 7 are comparable to those of other red supergiants that have previously been studied using interferometry., Comment: 12 pages, 11 figures, 3 tables. Accepted for publication in Astronomy and Astrophysics (A&A)
Published: 2021

24. The mass of β Pictoris c from β Pictoris b orbital motion

Author: Matthias Samland, Anne-Lise Maire, David Mouillet, Andreas Eckart, Valentin Christiaens, Julien Woillez, Sarah Blunt, K. Perraut, T. Paumard, T. Ott, Myriam Benisty, E. Nasedkin, A. Mérand, Z. Hubert, Stefan Hippler, Frank Eisenhauer, Roderick Dembet, Gilles Otten, F. H. Vincent, Pierre Léna, Jinyi Shangguan, Miriam Keppler, Ekkehard Wieprecht, G. Bourdarot, M. Houllé, Odele Straub, Alexander J. Bohn, M. Nowak, Felix Widmann, K. Ward-Duong, P. T. de Zeeuw, J.-B. Le Bouquin, Julia Stadler, T. Taro Shimizu, A. Boccaletti, David K. Sing, Ji Wang, Linda J. Tacconi, Arthur Vigan, Elodie Choquet, Jens Kammerer, Claudia Paladini, J. Rameau, R. J. García López, Xavier Haubois, E. Rickman, Guy Perrin, J. P. Berger, Wolfgang Brandner, Eric Gendron, G. Heißel, H. Bonnet, Laurent Jocou, A. Cridland, S. D. von Fellenberg, Pierre Kervella, R. Asensio-Torres, G. Rousset, O. Pfuhl, Erich Wiezorrek, M. Bonnefoy, Y. Clénet, Senol Yazici, R. Abuter, John D. Monnier, Laura Kreidberg, Paulo J. V. Garcia, Zafar Rustamkulov, Tomas Stolker, Gilles Duvert, Paul Mollière, H. Beust, Eckhard Sturm, António Amorim, Anne-Marie Lagrange, Paola Caselli, Christian Straubmeier, Th. Henning, G. Chauvin, Benjamin Charnay, Sylvestre Lacour, E. F. van Dishoeck, Jason Dexter, Stefan Gillessen, André Young, D. Lutz, V. Coudé du Foresto, R. Genzel, Feng Gao, J. H. Girard, Faustine Cantalloube, L. Rodet, Sasha Hinkley, A. Drescher, Vincent Lapeyrere, Laurent Pueyo, Matthew Horrobin, M. L. Bolzer, Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), MacoPharma, 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), Caltech Department of Astronomy [Pasadena], California Institute of Technology (CALTECH), Departamento de Astronomía, Universidad de Chile = University of Chile [Santiago] (UCHILE), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, European Southern Observatory (ESO), Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Max-Planck-Institut für Astronomie (MPIA), 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), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Service de Pathologie respiratoire et allergologie [CHU Limoges], CHU Limoges, University of Auckland [Auckland], the GRAVITY Collaboration, Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Harvard University-Smithsonian Institution, and Université de Genève = University of Geneva (UNIGE)
Subjects: Astrophysics - instrumentation and methods for astrophysics, planets and satellites: detection, 010504 meteorology & atmospheric sciences, Astrophysics, Astrophysics - Earth and planetary astrophysics, 01 natural sciences, High angular resolution, Planet, instrumentation: high angular resolution, 0103 physical sciences, Beta Pictoris, 10. No inequality, instrumentation: interferometers, 010303 astronomy & astrophysics, Instrumentation, 0105 earth and related environmental sciences, Orbital elements, Physics, Interferometers, Astronomy and Astrophysics, Astrometry, Exoplanet, Radial velocity, Detection, Space and Planetary Science, Orbital motion, Planets and satellites, Eccentricity (mathematics), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Aims.We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet.Methods.We combined previous astrometry ofβPictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion ofβPictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet,βPictoris c, was also reobserved at a separation of 96 mas, confirming the previous orbital estimations.Results.From the astrometry of planet b only, we can (i) detect the presence ofβPictoris c and (ii) constrain its mass to 10.04−3.10+4.53MJup. If one adds the astrometry ofβPictoris c, the mass is narrowed down to 9.15−1.06+1.08MJup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89−0.75+0.75MJup. With a semimajor axis of 2.68 ± 0.02 au, a period of 1221 ± 15 days, and an eccentricity of 0.32 ± 0.02, the orbital parameters ofβPictoris c are now constrained as precisely as those ofβPictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets’ dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet.
Published: 2021

25. Improved GRAVITY astrometric accuracy from modeling of optical aberrations

Author: Stefan Hippler, Maryam Habibi, S. Yazici, Paulo J. V. Garcia, T. Taro Shimizu, Roberto Abuter, F. Vincent, Linda J. Tacconi, M. Bauböck, Pierre Kervella, Guy Perrin, Idel Waisberg, G. Heißel, Karine Perraut, Eckhard Sturm, Laurent Jocou, Lieselotte Jochum, Sebastian Rabien, Julien Woillez, A. Jiménez-Rosales, Gérard Zins, M. Nowak, Odele Straub, Dieter Lutz, J.-B. Le Bouquin, Ekkehard Wieprecht, Julia Stadler, Reinhard Genzel, Wolfgang Brandner, Feng Gao, Thomas Ott, A. Drescher, N. M. Förster Schreiber, S. von Fellenberg, Christian Straubmeier, Silvia Scheithauer, Ric Davies, Y. Dallilar, Th. Henning, H. Bonnet, Jinyi Shangguan, Eric Gendron, Andreas Eckart, Yann Clénet, P. T. de Zeeuw, Thibaut Paumard, Jason Dexter, Andreas Kaufer, Felix Widmann, Frank Eisenhauer, Pierre Léna, V. Lapeyrère, Xavier Haubois, Erich Wiezorrek, Matthew Horrobin, Sylvestre Lacour, António Amorim, Jean-Philippe Berger, G. Rodríguez-Coira, Oliver Pfuhl, Stefan Gillessen, André Young, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and 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)
Subjects: Astrophysics - instrumentation and methods for astrophysics, Field (physics), Astrophysics - astrophysics of galaxies, FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, 010309 optics, Telescope, law, Methods: data analysis, 0103 physical sciences, Binary star, Calibration, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Physics, Galaxy: center, Galactic Center, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrometry, Galaxy: fundamental parameters, Interferometry, Space and Planetary Science, Instrumentation: interferometers, Astrophysics of Galaxies (astro-ph.GA), Instrumentation: high angular resolution, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA]
Abstract: The GRAVITY instrument on the ESO VLTI pioneers the field of high-precision near-infrared interferometry by providing astrometry at the 10−100 μas level. Measurements at this high precision crucially depend on the control of systematic effects. We investigate how aberrations introduced by small optical imperfections along the path from the telescope to the detector affect the astrometry. We develop an analytical model that describes the effect of these aberrations on the measurement of complex visibilities. Our formalism accounts for pupil-plane and focal-plane aberrations, as well as for the interplay between static and turbulent aberrations, and it successfully reproduces calibration measurements of a binary star. The Galactic Center observations with GRAVITY in 2017 and 2018, when both Sgr A* and the star S2 were targeted in a single fiber pointing, are affected by these aberrations at a level lower than 0.5 mas. Removal of these effects brings the measurement in harmony with the dual-beam observations of 2019 and 2020, which are not affected by these aberrations. This also resolves the small systematic discrepancies between the derived distance R0 to the Galactic Center that were reported previously.
Published: 2021
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26. Dimensioning adaptive optics for future VLTI projects

Author: Jean-Baptiste Le Bouquin, Dieter Lutz, Stefan Gillessen, Julien Woillez, Maximilian Haase, Christopher Mandla, F. Haussmann, Florentin Millour, Nikhil More, C. Rau, Olivier Lai, Fabien Patru, Thomas Ott, Josef Schubert, Senol Yazici, Michael Hartl, Marcel Carbillet, Frank Eisenhauer, T. Paumard, Ekkehard Wieprecht, European Southern Observatory (ESO), Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Max Planck Institute for Extraterrestrial Physics (MPE), and Max-Planck-Gesellschaft
Subjects: Very Large Telescope, Computer science, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, 01 natural sciences, 7. Clean energy, Deformable mirror, law.invention, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 010309 optics, Telescope, Interferometry, Upgrade, Observatory, law, 0103 physical sciences, Aerospace engineering, business, Adaptive optics, 010303 astronomy & astrophysics, Dimensioning
Abstract: The European Southern Observatory gives the opportunity to develop new third generation instruments for the Very Large Telescope Interferometer. Therefore, adaptive optics systems need to be upgraded, either for NAOMI on a 1.8-m auxiliary telescope or for MACAO on a 8-m unit telescope. It enables to access to new science cases such as active galactic nuclei with the GRAVITY+ project. We study here the requirements of such AO upgrade by increasing the number of sub-apertures of the wave-front sensor and the number of actuators of the deformable mirror. We evaluate the needs for a high-Strehl mode in the visible and near infrared wavelengths in various conditions of observation. We present numerical simulations to quantify the performance. We show that a moderate upgrade of NAOMI, and a significant upgrade of MACAO can enable both better dynamic range and sensitivity with the VLTI.
Published: 2020

27. Static phase aberrations in near-IR interferometry and GRAVITY's determination of the galactic center distanceStatic phase aberrations in near-IR interferometry and GRAVITY's determination of the galactic center distance

Author: M. Nowak, Reinhard Genzel, Wolfgang Brandner, K. Rousselet-Perraut, Julien Woillez, Christian Straubmeier, Eckhard Sturm, Sylvestre Lacour, Felix Widmann, Sebastiano von Fellenberg, M. Bauböck, Guy Perin, Jinyi Shangguan, Odele Straub, Frank Eisenhauer, A. Jiménez-Rosales, Paulo J. V. Garcia, António Amorim, Stefan Gillessen, Julia Stadler, Feng Gao, O. Pfuhl, and Thomas Ott
Subjects: Physics, Gravity (chemistry), business.industry, Zernike polynomials, Galactic Center, Phase (waves), Astrometry, Interferometry, symbols.namesake, Optics, Optical path, symbols, Calibration, business
Abstract: The GRAVITY instrument has revolutionized optical/IR interferometry: fringe-tracking and phase-referencing allow for 30 micro-arcsecond astrometry in a dual beam mode, and for spectro-differential astrometry better than 10 micro-arcseconds. The control of systematic effects is essential to fully exploit this technological advancement. Among those systematics are static phase aberrations, introduced along the instrument's optical path, which in particular affect the inferred separation of two unresolved objects within the same FOV. Here, we present how the aberrations can be measured, characterized by low-order Zernike polynomials and, most importantly, how their impact on the astrometry is corrected. The resulting astrometry corrections are verified with calibration observations of a binary before we discuss how they affect GRAVITY's measurement of the galactic center distance.
Published: 2020

28. First four telescopes large-separation off-axis fringe-tracking interferometry with GRAVITY at the VLTI

Author: Jinyi Shangguan, Feng Gao, Wolfgang Brandner, Frank Eisenhauer, F. Haussmann, Thomas Ott, Guy Perrin, Christian Straubmeier, Pierre Bourget, Frédéric Gonté, Eckhard Sturm, Michael Hartl, Roderick Dembet, Antonia Drescher, Sebastiano von Fellenberg, Nicolas Schuhler, Stefan Gillessen, Jürgen Ott, Gérard Zins, Julien Woillez, Paulo J. V. Garcia, O. Pfuhl, Thibaut Paumard, Karine Perraut, Michi Bauboeck, Odele Straub, Mari Lena Bolzer, Reinhard Genzel, Dieter Lutz, Felix Widmann, António Amorim, Julia Stadler, A. Jiménez-Rosales, Taro Shimizu, Bruno Chazelas, and Matthew Horrobin
Subjects: Physics, Very Large Telescope, Galactic Center, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Quasar, Astrophysics::Cosmology and Extragalactic Astrophysics, Tracking (particle physics), Redshift, Interferometry, Palomar Testbed Interferometer, Astronomical interferometer, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: We present the successful demonstration of world's first large-separation ~30" off-axis fringe tracking with four telescopes in October 2019. With this technique we increase the sky-coverage for optical interferometry by orders of magnitude compared to current technology. Following the early work at the Palomar Testbed Interferometer, the first demonstration of off-axis fringe tracking at the Keck Interferometer and with PRIMA at the ESO Very Large Telescope Interferometer, and the breakthrough with the GRAVITY Galactic Center observations, we enhanced the VLTI infrastructure for GRAVITY to take advantage of the PRIMA Star separators and Differential Delay Lines for off-axis fringe tracking. In our presentation we give an introduction to the subject, present the enhancements of the VLTI, and present our results from the first on-sky operation in October 2019, with observations of the Orion Trapezium Cluster, a field brown dwarf, and a high redshift quasar.
Published: 2020

29. VLTI status update: tapping into a powerful second-generation instrumentation

Author: Mario Tapia, Nicolas Schuhler, M. Riquelme, Bruno Lopez, Andres Pino, Lorena Faundez, Christophe Verinaud, Frank Eisenhauer, J. Beltran, A. Ramirez, Pierre van der Heyden, Lieselotte Jochum, Jean-Baptiste Le Bouquin, J. P. Kirchbauer, Fernando Salgado, Claudia Cid, Richard Tamblay, Thibaut Moulin, Alexander Meister, Andreas Glindemann, Pierre Haguenauer, Javier Reyes, F. Delplancke-Ströbele, Angela Cortes, P. Guajardo, Stefan Huber, Anthony Meilland, Jürgen Ott, Sylvestre Lacour, Steffen Mieske, Julien Leclercq, S. Rochat, Marcus Pavez, Diego Del Valle, S. Guieu, Konrad R. W. Tristram, Sebastien Egner, Pierre Bourget, Luca Pasquini, A. Delboulbe, Christian Stephan, Pascaline Darré, Roderick Dembet, Christian A. Hummel, Peter Krempl, Marcos Suarez, Alain Smette, Pavel Shchekaturov, Yves Magnard, Ralf Conzelmann, Emmanuel Aller-Carpentier, Norbert Hubin, Isabelle Percheron, Frédéric Gonté, Jean Louis Lizon, Claudia Paladini, Thibaut Guerlet, Pablo Gutierrez, Jean-Philippe Berger, Antoine Mérand, Juan Pablo Gil, Célia Pelluet, Luis Caniguante, Johan Kosmalski, Markus Schöller, Reinaldo Donoso, Christophe Dupuy, Lorenzo Pettazzi, Laurent Jocou, Jaime Gonzales, Guillermo Valdes, Markus Wittkowski, Julien Woillez, Daniel Gaytan, Jaime Alonso, Sébastien Poupar, Xavier Haubois, Roberto Abuter, Gérard Zins, Bruno Chazelas, Eloy Fuenteseca, Paul Bristow, Laurent Pallanca, R. Frahm, Thomas Rivinius, Johann Kolb, and Juan Osorio
Subjects: Interferometry, Upgrade, Computer science, Real-time computing, Tapping, Context (language use), Instrumentation (computer programming), Adaptive optics, Status report
Abstract: Following the arrival of MATISSE, the second-generation of VLTI instrumentation is now complete and was simultaneously enhanced by a major facility upgrade including the NAOMI Adaptive Optics on the Auxiliary Telescopes. On the Unit Telescopes, significant efforts were also made to improve the injection stability into VLTI instruments. On top of GRAVITY's own evolution, its fringe tracker is now being used to allow coherent integrations on MATISSE (the so-called GRA4MAT project). Meanwhile, operations also evolved to be more flexible and make the most of an extended observing parameter space. In this context, we present an overview of the current VLTI performances. Finally, we will report on on-going improvements such as the extension of the longest baselines.
Published: 2020

30. Infrared wavefront sensing for adaptive optics assisted galactic center observations with GRAVITY

Author: Julien Woillez, Gérard Zins, Johann Kolb, F. Delplancke-Ströbele, Wolfgang Brandner, Frank Eisenhauer, Casey Deen, Henri Bonnet, Silvia Scheithauer, Peter Bizenberger, Gert Finger, Eric Müller, Johana Panduro, Stefan Hippler, Laurent Pallanca, Z. Hubert, and Martin Kulas
Subjects: Wavefront, Physics, Very Large Telescope, business.industry, Galactic Center, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Wavefront sensor, Interferometry, Optics, Computer Science::Programming Languages, Astrophysics::Earth and Planetary Astrophysics, business, Focus (optics), Adaptive optics
Abstract: We describe the operation of the infrared wavefront sensing based Adaptive Optics system CIAO. The Coude Infrared Adaptive Optics (CIAO) system is a central auxiliary component of the Very Large Telescope interferometer (VLTI). It enables in particular Galactic Center observations using the GRAVITY interferometric instrument. CIAO compensates for phase disturbances caused by atmospheric turbulence, which all four 8 m Unit Telescopes (UT) experience during observation. Each of the four CIAO units generates an almost diffraction-limited image quality at its UT, which ensures that maximum flux of the observed stellar object enters the input fibers of GRAVITY. We present CIAO performance data obtained in the first 3 years of operation. We describe how CIAO is configured and used for observations with GRAVITY. We focus on the outstanding features of the infrared sensitive Saphira detector, which is used for the first time on Paranal, and show how it works as a wavefront sensor detector.
Published: 2020

31. Direct confirmation of the radial-velocity planet β Pictoris c

Author: Benjamin Charnay, Feng Gao, Antoine Mérand, L. Rodet, H. Bonnet, Tyler Gardner, Jean-Phillipe Berger, E. F. van Dishoeck, Anthony Boccaletti, Stefan Gillessen, Felix Widmann, Eric Gendron, Hervé Beust, Karine Perraut, Wolfgang Brandner, A. Cridland, J. Rameau, Sasha Hinkley, R. Asensio-Torres, Stefan Hippler, Roderick Dembet, Thibaut Paumard, John D. Monnier, Claudia Paladini, Valentin Christiaens, Julien Woillez, Linda J. Tacconi, Gilles Otten, Z. Hubert, V. Lapeyrère, Xavier Haubois, António Amorim, Guy Perrin, Jinyi Shangguan, Jingxiu Wang, R. Garcia Lopez, David Mouillet, Erich Wiezorrek, M. Nowak, Reinhard Genzel, Sylvestre Lacour, P. Rubini, G. Heißel, Gilles Duvert, Odele Straub, J.-B. Le Bouquin, Thomas Ott, Jens Kammerer, Anne-Lise Maire, A. Drescher, Laura Kreidberg, G. Rodríguez-Coira, O. Pfuhl, Paulo J. V. Garcia, Laurent Pueyo, A. Grandjean, Frank Eisenhauer, Yann Clénet, P. T. de Zeeuw, Pierre Léna, Matthew Horrobin, V. Coudé du Foresto, Roberto Abuter, Anne-Marie Lagrange, S. D. von Fellenberg, Tomas Stolker, Gérard Rousset, F. Vincent, Pierre Kervella, Faustine Cantalloube, Julien Girard, Andreas Eckart, Arthur Vigan, Mickael Bonnefoy, Paul Mollière, Silvia Scheithauer, André Müller, Miriam Keppler, Ekkehard Wieprecht, E. Nasedkin, Christian Straubmeier, Th. Henning, Jason Dexter, Sarah Blunt, Myriam Benisty, M. Houllé, K. Ward-Duong, Julia Stadler, A. Jiménez-Rosales, Eckhard Sturm, Laurent Jocou, M. Kulikauskas, M. Bauböck, Elodie Choquet, 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), 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), and 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)
Subjects: planets and satellites, Astrophysics, 01 natural sciences, Luminosity, formation -techniques, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, detection -planets and satellites, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Planetary core, Giant planet, Astronomy and Astrophysics, Orbital period, Exoplanet, Accretion (astrophysics), Radial velocity, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], interferometric, Astrophysics::Earth and Planetary Astrophysics
Abstract: Context.Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct detection is more sensitive to planets orbiting at a large distance from their host star. This dichotomy makes it difficult to combine the two techniques on a single target at once.Aims.Simultaneous measurements made by direct and indirect techniques offer the possibility of determining the mass and luminosity of planets and a method of testing formation models. Here, we aim to show how long-baseline interferometric observations guided by radial-velocity can be used in such a way.Methods.We observed the recently-discovered giant planetβPictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer.Results.This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature ofT = 1250 ± 50 K and a dynamical mass ofM = 8.2 ± 0.8 MJup. At 18.5 ± 2.5 Myr, this putsβPic c close to a ‘hot start’ track, which is usually associated with formation via disk instability. Conversely, the planet orbits at a distance of 2.7 au, which is too close for disk instability to occur. The low apparent magnitude (MK = 14.3 ± 0.1) favours a core accretion scenario.Conclusions.We suggest that this apparent contradiction is a sign of hot core accretion, for example, due to the mass of the planetary core or the existence of a high-temperature accretion shock during formation.
Published: 2020

32. Unveiling the β Pictoris system, coupling high contrast imaging, interferometric, and radial velocity data

Author: Christian Straubmeier, J. Hagelberg, Anne-Marie Lagrange, A. Grandjean, Frank Eisenhauer, Myriam Benisty, Silvano Desidera, R. Asensio-Torres, Anne-Lise Maire, M. Nowak, Thibaut Paumard, F. Cantalloube, Jens Kammerer, Yann Clénet, P. T. de Zeeuw, Matthew Horrobin, Karine Perraut, Eric Gendron, O. Pfuhl, L. Pueyo, Stefan Gillessen, Stefan Hippler, John Monnier, Raphael Galicher, P. Thebault, Gael Chauvin, C. Babusiaux, J. Wang, Wolfgang Brandner, L. Kreidberg, P. Léna, V. Lapeyrère, J. M. Girard, Sylvestre Lacour, G. Rodríguez-Coira, Guy Perrin, Matthew A. Kenworthy, H. Le Coroller, G. Heissel, F. Galland, V. Christiaens, P. Delorme, V. Coudé du Foresto, E. Choquet, Matthias Samland, Hervé Beust, Miriam Keppler, Odele Straub, Mickael Bonnefoy, Gilles Duvert, Andreas Eckart, Z. Wahhaj, T. Stolker, A. Zurlo, C. Paladini, F. Vincent, G. Otten, M. Janson, O. Flasseur, J.-B. Le Bouquin, A. Mérand, Felix Widmann, G. Rousset, Jinyi Shangguan, N. Meunier, Feng Gao, R. Gratton, A. Vigan, Paul Mollière, Jean-Phillipe Berger, P. Rubini, P. Kervella, T. Henning, António Amorim, T. Schmidt, Julien Woillez, Xavier Haubois, Anthony Boccaletti, Maud Langlois, Q. Kral, P. Garcia, Thomas Ott, L. Rodet, B. Charnay, R. Garcia Lopez, Reinhard Genzel, Sergio Messina, 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), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), 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 Paris Cité (UPCité), 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), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory [Santiago] (ESO), European Southern Observatory (ESO), CENTRA-SIM, IDL-Faculdade de Ciencias da Universidade de Lisboa, Departamento de Astronomía, Universidad de Chile = University of Chile [Santiago] (UCHILE), Max-Planck-Institut für Radioastronomie (MPIFR), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire des Combustibles Uranium (LCU), Service d'Analyses, d'Elaboration, d'Expérientations et d'Examens des combustibles (SA3E), Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Physikalisches Institut [Köln], Universität zu Köln = University of Cologne, Max-Planck-Institut für Astronomie (MPIA), University of Freiburg [Freiburg], Space Telescope Science Institute (STSci), German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), the GRAVITY Collaboration, Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), 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), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), 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), Centre d'Immunologie de Marseille - Luminy (CIML), Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Observatoire de Paris - Site de Paris (OP), Universität zu Köln, 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), Institut de Recherche pour le Développement (IRD), and Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: planets and satellites: detection, media_common.quotation_subject, Context (language use), Astrophysics, 01 natural sciences, Planet, radial velocities -planets and satellites, 0103 physical sciences, techniques: radial velocities, Astrophysics::Solar and Stellar Astrophysics, Eccentricity (behavior), 10. No inequality, planets and satellites: fundamental parameters, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common, Orbital elements, Physics, [PHYS]Physics [physics], detectionplanets and satellites, 010308 nuclear & particles physics, high angular resolution -techniques, Giant planet, techniques: high angular resolution, Astronomy and Astrophysics, Astrometry, Planetary system, Radial velocity, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], techniques, fundamental parameters
Abstract: Context. The nearby and young β Pictoris system hosts a well resolved disk, a directly imaged massive giant planet orbiting at ≃9 au, as well as an inner planet orbiting at ≃2.7 au, which was recently detected through radial velocity (RV). As such, it offers several unique opportunities for detailed studies of planetary system formation and early evolution. Aims. We aim to further constrain the orbital and physical properties of β Pictoris b and c using a combination of high contrast imaging, long base-line interferometry, and RV data. We also predict the closest approaches or the transit times of both planets, and we constrain the presence of additional planets in the system. Methods. We obtained six additional epochs of SPHERE data, six additional epochs of GRAVITY data, and five additional epochs of RV data. We combined these various types of data in a single Markov-chain Monte Carlo analysis to constrain the orbital parameters and masses of the two planets simultaneously. The analysis takes into account the gravitational influence of both planets on the star and hence their relative astrometry. Secondly, we used the RV and high contrast imaging data to derive the probabilities of presence of additional planets throughout the disk, and we tested the impact of absolute astrometry. Results. The orbital properties of both planets are constrained with a semi-major axis of 9.8 ± 0.4 au and 2.7 ± 0.02 au for b and c, respectively, and eccentricities of 0.09 ± 0.1 and 0.27 ± 0.07, assuming the HIPPARCOS distance. We note that despite these low fitting error bars, the eccentricity of β Pictoris c might still be over-estimated. If no prior is provided on the mass of β Pictoris b, we obtain a very low value that is inconsistent with what is derived from brightness-mass models. When we set an evolutionary model motivated prior to the mass of β Pictoris b, we find a solution in the 10–11 MJup range. Conversely, β Pictoris c’s mass is well constrained, at 7.8 ± 0.4 MJup, assuming both planets are on coplanar orbits. These values depend on the assumptions on the distance of the β Pictoris system. The absolute astrometry HIPPARCOS-Gaia data are consistent with the solutions presented here at the 2σ level, but these solutions are fully driven by the relative astrometry plus RV data. Finally, we derive unprecedented limits on the presence of additional planets in the disk. We can now exclude the presence of planets that are more massive than about 2.5 MJup closer than 3 au, and more massive than 3.5 MJup between 3 and 7.5 au. Beyond 7.5 au, we exclude the presence of planets that are more massive than 1–2 MJup. Conclusions. Combining relative astrometry and RVs allows one to precisely constrain the orbital parameters of both planets and to give lower limits to potential additional planets throughout the disk. The mass of β Pictoris c is also well constrained, while additional RV data with appropriate observing strategies are required to properly constrain the mass of β Pictoris b.
Published: 2020

33. A measure of the size of the magnetospheric accretion region in TW Hydrae

Author: Pierre Kervella, Y. Clénet, M. Filho, Stefan Hippler, Wolfgang Brandner, Tom Ray, Ekkehard Wieprecht, S. Yazici, S. von Fellenberg, O. Pfuhl, M. Bauboeck, J. Sanchez-Bermudez, Andreas Eckart, C. E. Garcia Dabo, A. Ramirez, R. Fedriani, Maryam Habibi, Paulo J. V. Garcia, F. H. Vincent, M. Koutoulaki, António Amorim, Julia Stadler, T. de Zeeuw, A. Jimenez Rosales, Feng Gao, Catherine Dougados, Felix Widmann, Karine Perraut, Lucas Labadie, Myriam Benisty, R. Garcia Lopez, Reinhard Genzel, H. Bonnet, A. Buron, E. F. van Dishoeck, Silvia Scheithauer, W. J. de Wit, Jinyi Shangguan, Stefan Gillessen, T. Ott, Frank Eisenhauer, T. Paumard, Sylvestre Lacour, Pierre Léna, V. Coudé du Foresto, Matthew Horrobin, Julien Woillez, Jean-Philippe Berger, F. Haussmann, A. Natta, L. Klarmann, Z. Hubert, Odele Straub, J.-B. Le Bouquin, Johann Kolb, Erich Wiezorrek, Eckhard Sturm, Laurent Jocou, Guy Perrin, A. Caratti o Garatti, R. Grellmann, Eric Gendron, Christian Straubmeier, Th. Henning, C. Rau, Xavier Haubois, M. Wiest, Roberto Abuter, Gilles Duvert, Paola Caselli, Gérard Zins, G. Rousset, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), School of Cosmic Physics [Dublin], and Dublin Institute for Advanced Studies (DIAS)
Subjects: Young stellar object, Astrophysics::High Energy Astrophysical Phenomena, Magnetosphere, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, TW Hydrae, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, Multidisciplinary, 010308 nuclear & particles physics, Stellar magnetic field, Radius, Accretion (astrophysics), Stars, T Tauri star, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, [SDU]Sciences of the Universe [physics], Astrophysics::Earth and Planetary Astrophysics
Abstract: Stars form by accreting material from their surrounding disks. There is a consensus that matter flowing through the disk is channelled onto the stellar surface by the stellar magnetic field. This is thought to be strong enough to truncate the disk close to the so-called corotation radius where the disk rotates at the same rate as the star. Spectro-interferometric studies in young stellar objects show that Hydrogen is mostly emitted in a region of a few milliarcseconds across, usually located within the dust sublimation radius. Its origin is still a matter of debate and it can be interpreted as coming from the stellar magnetosphere, a rotating wind or a disk. In the case of intermediate-mass Herbig AeBe stars, the fact that the Br gamma emission is spatially resolved rules out that most of the emission comes from the magnetosphere. This is due to the weak magnetic fields (some tenths of G) detected in these sources, resulting in very compact magnetospheres. In the case of T Tauri sources, their larger magnetospheres should make them easier to resolve. However, the small angular size of the magnetosphere (a few tenths of milliarcseconds), along with the presence of winds emitting in Hydrogen make the observations interpretation challenging. Here, we present direct evidence of magnetospheric accretion by spatially resolving the inner disk of the 60 pc T Tauri star TW Hydrae through optical long baseline interferometry. We find that the hydrogen near-infrared emission comes from a region approximately 3.5 stellar radii (R*) across. This region is within the continuum dusty disk emitting region (Rcont = 7 R*) and smaller than the corotation radius which is twice as big. This indicates that the hydrogen emission originates at the accretion columns, as expected in magnetospheric accretion models, rather than in a wind emitted at much larger distance (>1au)., Publish in Nature
Published: 2020

34. Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole

Author: Wolfgang Brandner, Thomas Ott, S. von Fellenberg, Thibaut Paumard, Jason Dexter, S. Yazici, V. Lapeyrère, Reinhard Genzel, Andreas Eckart, Xavier Haubois, Gérard Zins, Karine Perraut, Odele Straub, Stefan Hippler, Christian Straubmeier, Jean-Philippe Berger, António Amorim, M. Bauböck, J.-B. Le Bouquin, Th. Henning, Yann Clénet, P. T. de Zeeuw, Idel Waisberg, Eckhard Sturm, Sylvestre Lacour, Laurent Jocou, H. Bonnet, Jinyi Shangguan, Linda J. Tacconi, Silvia Scheithauer, Eric Gendron, Guy Perrin, M. Nowak, Maryam Habibi, Ekkehard Wieprecht, Felix Widmann, Andreas Kaufer, Julien Woillez, Matthew Horrobin, N. M. Förster Schreiber, Erich Wiezorrek, Frank Eisenhauer, Pierre Léna, Paulo J. V. Garcia, A. Jiménez-Rosales, G. Rodríguez-Coira, F. Vincent, Pierre Kervella, Oliver Pfuhl, Feng Gao, Vitor Cardoso, Lieselotte Jochum, Julia Stadler, Stefan Gillessen, Roberto Abuter, Observatoire de Paris, Université Paris sciences et lettres (PSL), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), 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), GRAVITY, and 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)
Subjects: Astrophysics and Astronomy, gr-qc, astro-ph.GA, black hole physics, Highly elliptical orbit, FOS: Physical sciences, Astrophysics, General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, General Relativity and Quantum Cosmology, symbols.namesake, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, relativistic processes, Physics, Galaxy: nucleus, 010308 nuclear & particles physics, General Relativity and Cosmology, Astronomy and Astrophysics, Orbital period, Astrophysics - Astrophysics of Galaxies, Black hole, Radial velocity, Orbit, Space and Planetary Science, gravitation, [SDU]Sciences of the Universe [physics], Kepler orbit, Astrophysics of Galaxies (astro-ph.GA), [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Precession, symbols, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, Schwarzschild radius, astro-ph.IM
Abstract: The star S2 orbiting the compact radio source Sgr A* is a precision probe of the gravitational field around the closest massive black hole (candidate). Over the last 2.7 decades we have monitored the star's radial velocity and motion on the sky, mainly with the SINFONI and NACO adaptive optics (AO) instruments on the ESO VLT, and since 2017, with the four-telescope interferometric beam combiner instrument GRAVITY. In this paper we report the first detection of the General Relativity (GR) Schwarzschild Precession (SP) in S2's orbit. Owing to its highly elliptical orbit (e = 0.88), S2's SP is mainly a kink between the pre-and post-pericentre directions of motion ~ +- 1 year around pericentre passage, relative to the corresponding Kepler orbit. The superb 2017-2019 astrometry of GRAVITY defines the pericentre passage and outgoing direction. The incoming direction is anchored by 118 NACO-AO measurements of S2's position in the infrared reference frame, with an additional 75 direct measurements of the S2-Sgr A* separation during bright states ('flares') of Sgr A*. Our 14-parameter model fits for the distance, central mass, the position and motion of the reference frame of the AO astrometry relative to the mass, the six parameters of the orbit, as well as a dimensionless parameter f_SP for the SP (f_SP = 0 for Newton and 1 for GR). From data up to the end of 2019 we robustly detect the SP of S2, del phi = 12' per orbital period. From posterior fitting and MCMC Bayesian analysis with different weighting schemes and bootstrapping we find f_SP = 1.10 +- 0.19. The S2 data are fully consistent with GR. Any extended mass inside S2's orbit cannot exceed ~ 0.1% of the central mass. Any compact third mass inside the central arcsecond must be less than about 1000 M_sun., accepted to A&A
Published: 2020

35. VLTI-PIONIER imaging of the red supergiant V602 Carinae

Author: J. C. Guirado, B. Freytag, Andrea Chiavassa, Xavier Haubois, Susanne Höfner, Fabien Baron, Julien Woillez, J. B. Climent, Markus Wittkowski, J. M. Marcaide, European Southern Observatory (ESO), Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy [Uppsala], Uppsala University, Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: Physics, Very Large Telescope, 010308 nuclear & particles physics, Flux, FOS: Physical sciences, Astronomy and Astrophysics, Context (language use), Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 01 natural sciences, law.invention, Telescope, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, law, Angular diameter, 0103 physical sciences, Red supergiant, 010303 astronomy & astrophysics, Image resolution, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: Context. Red supergiant stars possess surface features and extended molecular atmospheres. Photospheric convection may be a crucial factor of the levitation of the outer atmospheric layers. However, the mechanism responsible is still poorly understood. Aims. We image the stellar surface of V602 Carinae (V602 Car) to constrain the morphology and contrast of the surface features and of the extended atmospheric layers. Methods. We observed V602 Car with the Very Large Telescope Interferometer (VLTI) PIONIER instrument (1.53-1.78 $\mathrm{\mu}$m) between May and July 2016, and April and July 2019 with different telescope configurations. We compared the image reconstructions with 81 temporal snapshots of 3D radiative-hydrodynamics (RHD) CO$^5$BOLD simulations in terms of contrast and morphology, using the Structural Similarity Index. Results. The interferometric data are compatible with an overall spherical disk of angular diameter 4.4$\pm$0.2 mas, and an extended molecular layer. In 2016, the reconstructed image reveals a bright arc-like feature toward the northern rim of the photospheric surface. In 2019, an arc-like feature is seen at a different orientation and a new peak of emission is detected on the opposite side. The contrasts of the reconstructed surface images are 11%$\pm$2% and 9%$\pm$2% for 2016 and 2019, respectively. The morphology and contrast of the two images are consistent with 3D RHD simulations, within our achieved spatial resolution and dynamic range. The extended molecular layer contributes 10--13% of the total flux with an angular diameter of 6--8 mas. It is present but not clearly visible in the reconstructed images because it is close to the limits of the achieved dynamic range. The presence of the molecular layer is not reproduced by the 3D RHD simulations. Conclusions..., Comment: 16 pages, 13 figures, accepted for publication in Astronomy and Astrophysics
Published: 2020

36. Betelgeuse scope: Single-mode-fibers-assisted optical interferometer design for dedicated stellar activity monitoring

Author: Steve Ertel, Ewan S. Douglas, Jean Baptiste Lebouquin, Sebastiaan Y. Haffert, Daniel P. Marrone, Jean Philippe Berger, Jordan Stone, Julien Woillez, Oscar M. Montoya, Narsireddy Anugu, Miguel Montargès, Katie M. Morzinski, Josh A. Eisner, John Monnier, and Stefan Kraus
Subjects: Physics, Betelgeuse, Optical fiber, business.industry, Aperture synthesis, Single-mode optical fiber, Astrophysics::Instrumentation and Methods for Astrophysics, Physics::Optics, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Optical telescope, law.invention, CHARA array, Interferometry, Optics, law, Astrophysics::Solar and Stellar Astrophysics, Red supergiant, Astrophysics - Instrumentation and Methods for Astrophysics, business, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics
Abstract: Betelgeuse has gone through a sudden shift in its brightness and dimmed mysteriously. This is likely caused by a hot blob of plasma ejected from Betelgeuse and then cooled to obscuring dust. If true, it is a remarkable opportunity to directly witness the formation of dust around a red supergiant star. Today's optical telescope facilities are not optimized for time-evolution monitoring of the Betelgeuse surface, so in this work, we propose a low-cost optical interferometer. The facility will consist of $12 \times 4$ inch optical telescopes mounted on the surface of a large radio dish for interferometric imaging; polarization-maintaining single-mode fibers will carry the coherent beams from the individual optical telescopes to an all-in-one beam combiner. A fast steering mirror assisted fiber injection system guides the flux into fibers. A metrology system senses vibration-induced piston errors in optical fibers, and these errors are corrected using fast-steering delay lines. We will present the design., Comment: Presented at SPIE Optics+Photonics conference, 9 pages, 3 figures
Published: 2020
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37. Peering into the formation history of β Pictoris b with VLTI/GRAVITY long-baseline interferometry

Author: Gérard Rousset, N. M. Förster Schreiber, E. F. van Dishoeck, Laurent Pueyo, Frank Eisenhauer, Pierre Léna, H. Bonnet, Jingxiu Wang, Eric Gendron, Stefan Gillessen, Anne-Lise Maire, Yann Clénet, P. T. de Zeeuw, Hervé Beust, Jinyi Shangguan, S. Yazici, Julien Woillez, Thibaut Paumard, Claudia Paladini, C. Collin, M. Nowak, Sylvestre Lacour, Thomas Ott, D. Ziegler, F. Chapron, António Amorim, Erich Wiezorrek, Oliver Pfuhl, Feng Gao, A. Buron, P. Fédou, Z. Hubert, R. Garcia Lopez, Reinhard Genzel, Wolfgang Brandner, Odele Straub, J.-B. Le Bouquin, Ekkehard Wieprecht, Jean-Phillipe Berger, Stefan Hippler, Benjamin Charnay, Eckhard Sturm, F. Vincent, Pierre Kervella, Faustine Cantalloube, Laurent Jocou, G. Rodríguez-Coira, Sebastian Rabien, Roberto Abuter, Anne-Marie Lagrange, Mickael Bonnefoy, C. Rau, Linda J. Tacconi, Guy Perrin, Andreas Eckart, Silvia Scheithauer, Felix Widmann, Karine Perraut, V. Lapeyrère, P. Mollière, Gilles Duvert, Christian Straubmeier, F. Haußmann, Th. Henning, Jason Dexter, V. Coudé du Foresto, R. Dembet, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and 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)
Subjects: Planetesimal, 010504 meteorology & atmospheric sciences, planets and satellites, formation -planets and satellites, atmospheres -techniques, FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, β Pictoris, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, individual, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Orbital elements, Physics, [PHYS]Physics [physics], Earth and Planetary Astrophysics (astro-ph.EP), Very Large Telescope, Giant planet, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrometry, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics::Earth and Planetary Astrophysics, interferometricstars, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, Planetary mass, Astrophysics - Earth and Planetary Astrophysics
Abstract: Our objective is to estimate the C/O ratio in the atmosphere of beta Pictoris b and obtain an estimate of the dynamical mass of the planet, as well as to refine its orbital parameters using high-precision astrometry. We used the GRAVITY instrument with the four 8.2 m telescopes of the Very Large Telescope Interferometer to obtain K-band spectro-interferometric data on $\beta$ Pic b. We extracted a medium resolution (R=500) K-band spectrum of the planet and a high-precision astrometric position. We estimated the planetary C/O ratio using two different approaches (forward modeling and free retrieval) from two different codes (ExoREM and petitRADTRANS, respectively). Finally, we used a simplified model of two formation scenarios (gravitational collapse and core-accretion) to determine which can best explain the measured C/O ratio. Our new astrometry disfavors a circular orbit for $\beta$ Pic b ($e=0.15^{+0.05}_{-0.04}$). Combined with previous results and with Hipparcos/GAIA measurements, this astrometry points to a planet mass of $M = 12.7\pm{}2.2\,M_\mathrm{Jup}$. This value is compatible with the mass derived with the free-retrieval code petitRADTRANS using spectral data only. The forward modeling and free-retrieval approches yield very similar results regarding the atmosphere of beta Pic b. In particular, the C/O ratios derived with the two codes are identical ($0.43\pm{}0.05$ vs $0.43^{+0.04}_{-0.03}$). We argue that if the stellar C/O in $\beta$ Pic is Solar, then this combination of a very high mass and a low C/O ratio for the planet suggests a formation through core-accretion, with strong planetesimal enrichment., Comment: 14 pages + 7 page appendix, 7 figures, accepted for pulication
Published: 2020

38. The GRAVITY Young Stellar Object survey I. Probing the disks of Herbig Ae/Be stars in terrestrial orbits

Author: S. Yazici, Oliver Pfuhl, Thomas Henning, J. Bouvier, Stefan Hippler, V. Coudé du Foresto, Thomas Ott, J. Sanchez-Bermudez, Lucas Labadie, E. F. van Dishoeck, Myriam Benisty, Sebastian Rabien, Stefan Gillessen, Frank Eisenhauer, Frederic H. Vincent, A. Caratti o Garatti, Karine Perraut, Chien-Cheng Lin, Laurent Jocou, Andreas Eckart, Jaime E. Pineda, Matthew Horrobin, Christian Straubmeier, Roberto Abuter, Idel Waisberg, Feng Gao, L. Klarmann, Catherine Dougados, Imke Wank, Antoine Mérand, C. Rau, Gérard Rousset, Felix Widmann, Sarah Kendrew, Guy Perrin, A. Buron, P. T. de Zeeuw, Thomas P. Ray, R. Grellmann, Wolfgang Brandner, António Amorim, Bernard Lazareff, Dominique Segura-Cox, Paulo Gordo, Erich Wiezorrek, Henri Bonnet, F. Eupen, Eric Gendron, F. Haussmann, M. Koutoulaki, Yann Clénet, Silvia Scheithauer, Xavier Haubois, Paola Caselli, M. Wiest, Paulo J. V. Garcia, Gilles Duvert, Reinhard Genzel, Julien Woillez, Thibaut Paumard, E. Sturm, Jason Dexter, Jean-Philippe Berger, Z. Hubert, Sylvestre Lacour, Odele Straub, J.-B. Le Bouquin, Pierre Léna, R. Garcia-Lopez, Ekkehard Wieprecht, Pierre Kervella, Faustine Cantalloube, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and 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)
Subjects: stars, Young stellar object, Population, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Planet, 0103 physical sciences, Thermal, Astrophysics::Solar and Stellar Astrophysics, high angular resolutiontechniques, education, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, Earth and Planetary Astrophysics (astro-ph.EP), education.field_of_study, Very Large Telescope, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), formation -circumstellar matter -infrared, interferometric, Closure phase, Terrestrial planet, Astrophysics::Earth and Planetary Astrophysics, ISM -techniques, Astrophysics - Earth and Planetary Astrophysics
Abstract: The formation and the evolution of protoplanetary disks are important stages in the lifetime of stars. The processes of disk evolution and planet formation are intrinsically linked. We spatially resolve with GRAVITY/VLTI in the K-band the sub au-scale region of 27 stars to gain statistical understanding of their properties. We look for correlations with stellar parameters, such as luminosity, mass, temperature and age. Our sample also cover a range of various properties in terms of reprocessed flux, flared or flat morphology, and gaps. We developed semi-physical geometrical models to fit our interferometric data. Our best models correspond to smooth and wide rings, implying that wedge-shaped rims at the dust sublimation edge are favored, as found in the H-band. The closure phases are generally non-null with a median value of ~10 deg, indicating spatial asymmetries of the intensity distributions. Multi-size grain populations could explain the closure phase ranges below 20-25 deg but other scenarios should be invoked to explain the largest ones. Our measurements extend the Radius-Luminosity relation to ~1e4 Lsun and confirm the significant spread around the mean relation observed in the H-band. Gapped sources exhibit a large N-to-K band size ratio and large values of this ratio are only observed for the members of our sample that would be older than 1 Ma, less massive, and with lower luminosity. In the 2 Ms mass range, we observe a correlation in the increase of the relative age with the transition from group II to group I, and an increase of the N-to-K size ratio. However, the size of the current sample does not yet permit us to invoke a clear universal evolution mechanism across the HAeBe mass range. The measured locations of the K-band emission suggest that these disks might be structured by forming young planets, rather than by depletion due to EUV, FUV, and X-ray photo-evaporation., Comment: Accepted for publication in A&A; 23 pages, 16 figures, 7 tables
Published: 2019

39. The GRAVITY young stellar object survey

Author: Paola Caselli, E. F. van Dishoeck, Feng Gao, Jaime E. Pineda, Karine Perraut, Lucas Labadie, Stefan Gillessen, Catherine Dougados, Felix Widmann, E. Sturm, Odele Straub, Eric Gendron, J.-B. Le Bouquin, Christian Straubmeier, L. Klarmann, Mercedes E. Filho, A. Eckart, Thomas Ott, J. Sanchez-Bermudez, Th. Henning, A. Drescher, V. Lapeyrère, Gérard Rousset, Zoltan Hubert, Matthew Horrobin, Paulo J. V. Garcia, Gilles Duvert, Julien Woillez, G. Heissel, Thibaut Paumard, Jean-Phillipe Berger, G. Rodríguez-Coira, R. Grellmann, Frederic H. Vincent, Laurent Jocou, J. Stadler, S. D. von Fellenberg, Sylvestre Lacour, António Amorim, Guy Perrin, Pierre Kervella, V. Coudé du Foresto, Frank Eisenhauer, R. Garcia Lopez, Reinhard Genzel, Dominique Segura-Cox, Pierre Léna, M. Bauböck, Myriam Benisty, T. Taro Shimizu, A. Caratti o Garatti, A. Jiménez-Rosales, Yann Clénet, P. T. de Zeeuw, Wolfgang Brandner, and Jinyi Shangguan
Subjects: Young stellar object, FOS: Physical sciences, Context (language use), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Angular resolution, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Very Large Telescope, 010308 nuclear & particles physics, Astronomy and Astrophysics, Accretion (astrophysics), Vortex, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract: Protoplanetary disks drive some of the formation process (e.g., accretion, gas dissipation, formation of structures, etc.) of stars and planets. Understanding such physical processes is one of the main astrophysical questions. HD 163296 is an interesting young stellar object for which infrared and sub-millimeter observations have shown a prominent circumstellar disk with gaps plausibly created by forming planets. This study aims at characterizing the morphology of the inner disk in HD 163296 with multi-epoch near-infrared interferometric observations performed with GRAVITY at the Very Large Telescope Interferometer (VLTI). Our goal is to depict the K-band (lambda_0 ~ 2.2 um) structure of the inner rim with milliarcsecond (sub-au) angular resolution. Our data is complemented with archival PIONIER (H-band; lambda_0 ~ 1.65 um) data of the source. We performed a Gradient Descent parametric model fitting to recover the sub-au morphology of our source. Our analysis shows the existence of an asymmetry in the disk surrounding the central star of HD 163296. We confirm variability of the disk structure in the inner ~2 mas (0.2 au). While variability of the inner disk structure in this source has been suggested by previous interferometric studies, this is the first time that it is confirmed in the H- and K-bands by using a complete analysis of the closure phases and squared visibilities over several epochs. Because of the separation from the star, position changes, and persistence of this asymmetric structure on timescales of several years, we argue that it is a dusty feature (e.g., a vortex or dust clouds), probably, made by a mixing of sillicate and carbon dust and/or refractory grains, inhomogeneously distributed above the mid-plane of the disk., Accepted to be published in Astronomy and Astrophysics; main-body: 11 pages, 3 figures and 3 tables
Published: 2021

40. NAOMI: the adaptive optics system of the Auxiliary Telescopes of the VLTI

Author: E. Cottalorda, C. Heritier, F. Delplancke-Ströbele, S. Zúñiga-Fernández, S. Guieu, Javier Reyes, M. Seidel, Alexander Meister, Laurent Jocou, Johan Kosmalski, G. Santos Tomás, Oliver Pfuhl, Pierre Bourget, Marcos Suarez, Christophe Verinaud, J. L. Beuzit, Anthony Meilland, Philippe B. Gitton, Andreas Haimerl, J.-B. Le Bouquin, Eric Stadler, C. Frank, Christophe Dupuy, Lorenzo Pettazzi, Pascaline Darré, Xavier Haubois, Gérard Zins, Frédéric Gonté, Jaime Alonso, Bruno Lopez, R. Donaldson, Peter Krempl, H. Bonnet, Pavel Shchekaturov, Johann Kolb, Frank Eisenhauer, Pablo Gutierrez, Thibaut Guerlet, Paul Lilley, Julien Woillez, J. P. Berger, Gerhard Fischer, M. Todorovic, Sebastien Egner, A. Mérand, Thibaut Moulin, Luis Caniguante, Christian Stephan, J. P. Kirchbauer, Luigi Andolfato, Guillermo Valdes, N. Hubin, D. Phan, Eloy Fuenteseca, Stewart McLay, M. Riedel, Isabelle Percheron, A. Delboulbe, Jerome Paufique, W. Pirani, Christian Schmid, Christian Soenke, J. Dupeyron, Jose Abad, Andrew Rakich, M. Le Louarn, Pablo Barriga, Stefan Huber, P. Haguenauer, Paul Jolley, G. Bourdarot, E. Aller Carpentier, R. Brast, Nicolas Schuhler, B. Delabre, Reinhold J. Dorn, Roderick Dembet, Sylvain Rochat, Roberto Abuter, Yves Magnard, J. Quentin, Luca Pasquini, R. Ridings, European Southern Observatory (ESO), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre Spatial Universitaire de Grenoble ( CSUG), CRLCC Eugène Marquis (CRLCC), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Wavefront, Coupling, Very Large Telescope, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Context (language use), Astrophysics, Tracking (particle physics), 01 natural sciences, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 010309 optics, Interferometry, Optics, Space and Planetary Science, 0103 physical sciences, Astronomical seeing, Astrophysics::Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, business, Adaptive optics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics
Abstract: The tip-tilt stabilisation system of the 1.8 m Auxiliary Telescopes of the Very Large Telescope Interferometer was never dimensioned for robust fringe tracking, except when atmospheric seeing conditions are excellent. Increasing the level of wavefront correction at the telescopes is expected to improve the coupling into the single-mode fibres of the instruments, and enable robust fringe tracking even in degraded conditions. We deployed a new adaptive optics module for interferometry (NAOMI) on the Auxiliary Telescopes. We present its design, performance, and effect on the observations that are carried out with the interferometric instruments., Comment: 10 pages, 18 figures, 2 tables, A&A forthcoming
Published: 2019

41. The GRAVITY fringe tracker

Author: Christian Straubmeier, Oliver Pfuhl, Elodie Choquet, Wolfgang Brandner, Xavier Haubois, P. Fédou, Roderick Dembet, Sylvestre Lacour, Guy Perrin, Burkhard Wolff, Julien Woillez, Karine Perraut, A. Ramirez, António Amorim, Konrad R. W. Tristram, Ekkehard Wieprecht, Roberto Abuter, Frédéric Cassaing, T. Ott, Erich Wiezorrek, Frank Eisenhauer, 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), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, University of Cambridge [UK] (CAM), European Southern Observatory (ESO), 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), DOTA, ONERA, Université Paris Saclay [Châtillon], ONERA-Université Paris-Saclay, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Universität zu Köln, Max-Planck-Institut für Astronomie (MPIA), SIM/IDL Faculdade de Ciências da Universidade de Lisboa (FCUL), University of Lisboa, 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), 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), DOTA, ONERA, Université Paris Saclay (COmUE) [Châtillon], ONERA-Université Paris Saclay (COmUE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Universität zu Köln = University of Cologne
Subjects: Time delay and integration, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Context (language use), Astrophysics, Tracking (particle physics), 01 natural sciences, Optics, Optical path, Control theory, 0103 physical sciences, instrumentation: interferometers, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, business.industry, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, techniques: high angular resolution, Astronomy and Astrophysics, Kalman filter, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Space and Planetary Science, Integrator, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, business
Abstract: The GRAVITY instrument has been commissioned on the VLTI during 2016 and is now available to the astronomical community. It is the first optical interferometer capable of observing sources as faint as magnitude 19 in K-band. This is possible thanks to the fringe tracker which compensates the differential piston based on measurements of a brighter off-axis astronomical reference source. The goal of this paper is to consign the main developments made in the context of the GRAVITY fringe tracker. This could serve as basis for future fringe tracking systems. The paper therefore covers all aspects of the fringe tracker, from hardware, to control software and on-sky observations. Special emphasis is placed on the interaction between the group delay controller and the phase delay controller. The group delay control loop is a simple but robust integrator. The phase delay controller is a state-space control loop based on an auto-regressive representation of the atmospheric and vibrational perturbations. A Kalman filter provides optimal determination of the state of the system. The fringe tracker shows good tracking performance on sources with coherent K magnitudes of 11 on the UTs and 9.5 on the ATs. It can track fringes with an SNR level of 1.5 per DIT, limited by photon and background noises. On the ATs, during good seeing conditions, the optical path delay residuals can be as low as 75 nm root mean square. On the UTs, the performance is limited to around 250 nm because of structural vibrations., Accepted in A&A. 18 pages
Published: 2019

42. SAGE: finding IMBH in the black hole desert

Author: Odele Straub, Lester David, F. H. Vincent, V. Lapeyrere, Aglae Kellerer, Julien Woillez, Karan Jani, Pierre Bourget, A. Le Tiec, J-Y. Vinet, M. Nowak, O. Godet, Sylvestre Lacour, J. Martino, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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), Laboratoire Univers et Théories (LUTH (UMR_8102)), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Relativiste Théories Expériences Métrologie Instrumentation Signaux (ARTEMIS), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), 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), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), 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), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), 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), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Nice Sophia Antipolis (1965 - 2019) (UNS), 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), and 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)
Subjects: coalescence, Physics and Astronomy (miscellaneous), Astrophysics::High Energy Astrophysical Phenomena, interferometer, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), triangulation, 01 natural sciences, 7. Clean energy, General Relativity and Quantum Cosmology, Observatory, 0103 physical sciences, 010306 general physics, effect: solar, orbit, Physics, Solar mass, Supermassive black hole, LISA, mass: solar, 010308 nuclear & particles physics, Gravitational wave, beam: width, Geosynchronous orbit, gravitational radiation, Astronomy, black hole: mass, Mass ratio, optics, recombination, laser, Black hole, observatory, detector: sensitivity, Interferometry, 13. Climate action, trajectory, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], mass ratio
Abstract: SAGE (SagnAc interferometer for Gravitational wavE) is a project for a space observatory based on multiple 12-U CubeSats in geosynchronous orbit. The objective is a fast track mission which would fill the observational gap between LISA and ground based observatories. With albeit a lower sensitivity, it would allow early investigation of the nature and event rate of intermediate-mass black hole (IMBH) mergers, constraining our understanding of the universe formation by probing the building up of IMBH up to supermassive black holes. Technically, the CubeSats would create a triangular Sagnac interferometer with 140.000km roundtrip arm length, optimized to be sensitive to gravitational waves at frequencies between 10mHz and 2Hz. The nature of the Sagnac measurement makes it almost insensitive to position error, enabling the use of spacecrafts in ballistic trajectories. The light source and recombination units of the interferometer are based on compact fibered technologies without bulk optics. A peak sensitivity of 23 pm/sqrt(Hz) is expected at 1Hz assuming a 200mW internal laser source and 10-centimeter diameter apertures. Because of the absence of a test mass, the main limitation would come from the non-gravitational forces applied on the spacecrafts. However, conditionally upon our ability to partially post-process the effect of solar wind and solar pressure, SAGE would allow detection of gravitational waves with strains as low as a few 1e-19 within the 0.1 to 1Hz range. Averaged over the entire sky, and including the antenna gain of the Sagnac interferometer, the SAGE observatory would sense equal mass black hole mergers in the 1e4 to 1e6 solar masses range up to a luminosity distance of 800Mpc. Additionally, coalescence of stellar black holes (10Msun) around SMBH (IMBH) forming extreme (intermediate) mass ratio inspirals could be detected within a sphere of radius 200Mpc., Comment: Accepted in Class. Quantum Grav
Published: 2019
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43. A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty

Author: Idel Waisberg, Thibaut Paumard, Julien Woillez, Jason Dexter, Oliver Pfuhl, Stefan Gillessen, Thomas Henning, Senol Yazici, Matthew Horrobin, Stefan Hippler, Christian Straubmeier, Karine Perraut, Odele Straub, J.-B. Le Bouquin, Sebastian Rabien, Amiel Sternberg, F. Vincent, António Amorim, Laurent Jocou, Vincent Lapeyrere, Reinhard Genzel, V. Coudé du Foresto, Feng Gao, Xavier Haubois, Gilles Duvert, Ekkehard Wieprecht, Jean-Philippe Berger, Paulo J. V. Garcia, Maryam Habibi, Thomas Ott, A. Jiménez-Rosales, Ortwin Gerhard, S. von Fellenberg, Linda J. Tacconi, G. Rousset, Eric Gendron, Guy Perrin, Pierre Kervella, Frank Eisenhauer, G. Rodriguez Coira, R. Abuter, Felix Widmann, Pierre Léna, Eckhard Sturm, Silvia Scheithauer, N. M. Förster Schreiber, Erich Wiezorrek, Henri Bonnet, Andreas Eckart, M. Bauböck, Sylvestre Lacour, Yann Clénet, P. T. de Zeeuw, Wolfgang Brandner, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), 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), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and 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)
Subjects: Physics, Galaxy: nucleus, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Galactic Center, black hole physics, FOS: Physical sciences, Astronomy and Astrophysics, Orbital eccentricity, Astrometry, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Redshift, Black hole, Orbit, Interferometry, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, astrometry, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Gravitational redshift
Abstract: We present a 0.16% precise and 0.27% accurate determination of R0, the distance to the Galactic Center. Our measurement uses the star S2 on its 16-year orbit around the massive black hole Sgr A* that we followed astrometrically and spectroscopically for 27 years. Since 2017, we added near-infrared interferometry with the VLTI beam combiner GRAVITY, yielding a direct measurement of the separation vector between S2 and Sgr A* with an accuracy as good as 20 micro-arcsec in the best cases. S2 passed the pericenter of its highly eccentric orbit in May 2018, and we followed the passage with dense sampling throughout the year. Together with our spectroscopy, in the best cases with an error of 7 km/s, this yields a geometric distance estimate: R0 = 8178 +- 13(stat.) +- 22(sys.) pc. This work updates our previous publication in which we reported the first detection of the gravitational redshift in the S2 data. The redshift term is now detected with a significance level of 20 sigma with f_redshift = 1.04 +- 0.05., Comment: 9 pages, 7 figures, submitted to A&A
Published: 2019
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44. An image of the dust sublimation region in the nucleus of NGC 1068

Author: Sebastian F. Hönig, António Amorim, Idel Waisberg, N. M. Förster Schreiber, Feng Gao, Wolfgang Brandner, Paulo J. V. Garcia, T. Taro Shimizu, Linda J. Tacconi, Amiel Sternberg, D. Gratadour, Guy Perrin, Konrad R. W. Tristram, Jason Dexter, Felix Widmann, Andreas Eckart, Mercedes Prieto, P.-O. Petrucci, Bradley M. Peterson, Karine Perraut, Oliver Pfuhl, Sylvestre Lacour, Eckhard Sturm, Frank Eisenhauer, Julien Woillez, Stefan Gillessen, Ric Davies, Jinyi Shangguan, Odele Straub, Dieter Lutz, Makoto Kishimoto, Yann Clénet, P. T. de Zeeuw, Hagai Netzer, P. Vermot, Thibaut Paumard, Thomas Ott, Florentin Millour, Daniel Rouan, Marc Schartmann, Reinhard Genzel, Christian Straubmeier, Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)
Subjects: 010504 meteorology & atmospheric sciences, galaxies: active, FOS: Physical sciences, Astrophysics, 01 natural sciences, Observatory, 0103 physical sciences, medicine, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Physics, Very Large Telescope, Astronomy and Astrophysics, Position angle, Astrophysics - Astrophysics of Galaxies, Galaxy, galaxies: Seyfert, Interferometry, medicine.anatomical_structure, Space and Planetary Science, techniques: interferometric, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Sublimation (phase transition), galaxies: nuclei, Nucleus
Abstract: We present near-infrared interferometric data on the Seyfert 2 galaxy NGC 1068, obtained with the GRAVITY instrument on the European Southern Observatory Very Large Telescope Interferometer. The extensive baseline coverage from 5 to 60 M\lambda allowed us to reconstruct a continuum image of the nucleus with an unrivaled 0.2 pc resolution in the K-band. We find a thin ring-like structure of emission with a radius r = 0.24+/-0.03 pc, inclination i = 70+/-5 deg, position angle PA = -50+/-4 deg, and h/r < 0.14, which we associate with the dust sublimation region. The observed morphology is inconsistent with the expected signatures of a geometrically and optically thick torus. Instead, the infrared emission shows a striking resemblance to the 22 GHz maser disc, which suggests they share a common region of origin. The near-infrared spectral energy distribution indicates a bolometric luminosity of (0.4-4.7) x 10^45 erg/s, behind a large A_K ~ 5.5 (A_V ~ 90) screen of extinction that also appears to contribute significantly to obscuring the broad line region., Comment: Accepted for publication in Astronomy and Astrophysics. 13 pages with 7 figures
Published: 2019
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45. Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA*

Author: Linda J. Tacconi, Eckhard Sturm, Laurent Jocou, Julien Woillez, Guy Perrin, Bernard Lazareff, Christian Straubmeier, P. M. Plewa, Stefan Hippler, H. Bonnet, Feng Gao, Eric Gendron, Th. Henning, Gérard Rousset, N. M. Förster Schreiber, Thomas Ott, Johana Panduro, Jean-Philippe Berger, P. Guajardo, Frank Eisenhauer, Karine Perraut, S. von Fellenberg, Yann Clénet, P. T. de Zeeuw, Felix Widmann, Pierre Léna, Thibaut Paumard, Oliver Pfuhl, Xavier Haubois, Erich Wiezorrek, V. Coudé du Foresto, Casey Deen, Sylvestre Lacour, Stefan Gillessen, Jason Dexter, Amiel Sternberg, Gilles Duvert, Matthew Horrobin, Odele Straub, J.-B. Le Bouquin, Armin Huber, Reinhard Genzel, Paulo J. V. Garcia, Sebastian Rabien, António Amorim, G. Rodríguez-Coira, Wolfgang Brandner, Frederic H. Vincent, Roberto Abuter, V. Lapeyrère, Idel Waisberg, Andreas Eckart, S. Yazici, Maryam Habibi, M. Bauböck, Pierre Kervella, Magdalena Lippa, A. Jiménez-Rosales, Ekkehard Wieprecht, European Southern Observatory (ESO), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, 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), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Radioastronomie (MPIFR), Max Planck Institute for Extraterrestrial Physics (MPE), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Transport et Environnement (INRETS/LTE), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Institut de biologie et chimie des protéines [Lyon] (IBCP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Swedish Space Corporation (SSC), School of Physics and Astronomy [Tel Aviv], Tel Aviv University [Tel Aviv], Laboratoire Univers et Théories (LUTH (UMR_8102)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, Universität zu Köln, AUTRES, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), 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), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), 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 Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)
Subjects: Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, Gravitation, Telescope, General Relativity and Quantum Cosmology, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Circular orbit, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, [PHYS]Physics [physics], Solar mass, 010308 nuclear & particles physics, Astronomy and Astrophysics, Polarization (waves), Astrophysics - Astrophysics of Galaxies, Interferometry, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Orbital motion, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Schwarzschild radius
Abstract: We report the detection of continuous positional and polarization changes of the compact source SgrA* in high states ('flares') of its variable near- infrared emission with the near-infrared GRAVITY-Very Large Telescope Interferometer (VLTI) beam-combining instrument. In three prominent bright flares, the position centroids exhibit clockwise looped motion on the sky, on scales of typically 150 micro-arcseconds over a few tens of minutes, corresponding to about 30% the speed of light. At the same time, the flares exhibit continuous rotation of the polarization angle, with about the same 45(+/-15)-minute period as that of the centroid motions. Modelling with relativistic ray tracing shows that these findings are all consistent with a near face-on, circular orbit of a compact polarized 'hot spot' of infrared synchrotron emission at approximately six to ten times the gravitational radius of a black hole of 4 million solar masses. This corresponds to the region just outside the innermost, stable, prograde circular orbit (ISCO) of a Schwarzschild-Kerr black hole, or near the retrograde ISCO of a highly spun-up Kerr hole. The polarization signature is consistent with orbital motion in a strong poloidal magnetic field., Comment: accepted by A&A; 16 pages
Published: 2018

46. Hi-5: a potential high-contrast thermal near-infrared imager for the VLTI

Author: Ettore Pedretti, Konrad R. W. Tristram, Michael J. Ireland, Jean-Phillipe Berger, Guillermo Martin, Alexandre Gallenne, Julien Woillez, Maddalena Reggiani, L. Labadie, John Monnier, P. Hinz, Stefan Kraus, Antoine Mérand, François Hénault, Bertrand Mennesson, Elsa Huby, Denis Defrere, Stefano Minardi, J.-B. Le Bouquin, William C. Danchi, Jean Surdej, J.-U. Pott, Olivier Absil, Steve Ertel, G. Orban de Xivry, Alexis Matter, Barnaby Norris, and Eugene Serabyn
Subjects: Physics, Active galactic nucleus, Infrared, Near-infrared spectroscopy, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy, Planetary system, 7. Clean energy, 01 natural sciences, Exoplanet, 010309 optics, Stars, Planet, Stellar physics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: Hi-5 is a high-contrast (or high dynamic range) infrared imager project for the VLTI. Its main goal is to characterize young extra-solar planetary systems and exozodiacal dust around southern main-sequence stars. In this paper, we present an update of the project and key technology pathways to improve the contrast achieved by the VLTI. In particular, we discuss the possibility to use integrated optics, proven in the near-infrared, in the thermal near-infrared (L and M bands, 3-5~$\mu$m) and advanced fringe tracking strategies. We also address the strong exoplanet science case (young exoplanets, planet formation, and exozodiacal disks) offered by this wavelength regime as well as other possible science cases such as stellar physics (fundamental parameters and multiplicity) and extragalactic astrophysics (active galactic nuclei and fundamental constants). Synergies and scientific preparation for other potential future instruments such as the Planet Formation Imager are also briefly discussed., Comment: 15 pages, 3 figures, SPIE proceedings, based on arXiv:1801.04148
Published: 2018

47. Characterization of ALPAO deformable mirrors for the NAOMI VLTI Auxiliary Telescopes adaptive optics

Author: S. Guieu, Jean-Philippe Berger, Sebastien Egner, Eric Cottalorda, Pierre Haguenauer, A. Delboulbe, S. Rochat, Jean-Baptiste Le Bouquin, Thibaut Moulin, Jean-Luc Beuzit, Yves Magnard, Laurent Jocou, Christophe Vérinaud, Julien Woillez, and Frédéric Gonté
Subjects: Very Large Telescope, Astronomical optical interferometry, Computer science, Zernike polynomials, business.industry, Bandwidth (signal processing), Deformable mirror, symbols.namesake, Interferometry, Optics, Software, symbols, business, Adaptive optics
Abstract: The Very Large Telescope Interferometer Auxiliary Telescopes will soon be equipped with an adaptive optics system called NAOMI. The corrective optics deformable mirror is the commercial DM241 from ALPAO. Being part of an interferometer operating from visible to mid-infrared, the DMs of NAOMI face several challenges (high level of reliability, open-loop chopping, piston-free control, WFS/DM pupil rotation, high desired bandwidth and stroke). We here describe our extensive characterization of the DMs through measurements and simulations. We summarize the operational scenario we have defined to handle the specific mirror properties. We conclude that the ALPAO DMs have overall excellent properties that fulfill most of the stringent requirements and that deviations from specifications are easily handled. To our knowledge, NAOMI will be the first astronomical system with a command in true Zernike modes (allowing software rotation), and the first astronomical system in which a chopping is performed with the deformable mirror (5” sky, at 5 Hz).
Published: 2018

48. Data reduction of the VLTI/GRAVITY interferometric instrument (Conference Presentation)

Author: Jean-Baptiste Le Bouquin, Cesar Enrique Garcia-Dabo, Pierre Kervella, Frank Eisenhauer, Sylvestre Lacour, Antoine Mérand, Julien Woillez, António Amorim, Guy Perrin, Karine Perraut, Christian Straubmeier, Wolfgang Brandner, and V. Lapeyrere
Subjects: Physics, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Phase (waves), Astrometry, Interference (wave propagation), Metrology, law.invention, Telescope, Interferometry, Optics, law, Calibration, business, Data reduction
Abstract: The new VLTI/GRAVITY instrument is a four telescope beam combiner installed at the VLT Interferometer. The principal novelty of this instrument is the availability of a dual field mode enabling narrow-angle relative astrometry at micro-arcsecond accuracy between two objects separated by several arcseconds. The fringe tracker (FT) stabilizes the interference fringes at up to 1 kHz frequency, allowing for long exposures with the science combiner (SC) as well as phase referenced imaging and differential astrometry (in dual field mode). The FT and SC beam combiners are integrated optics (IO) components, whose 24 outputs are (optionally) polarization-split and spectrally dispersed. The processing of the photometric signals from the IO components is based on the pixel-to-visibility matrix (P2VM) formalism, that translates them into complex visibilities. The retrieval of the relative phase of the two objects subsequently relies on the combination of the phases measured from the FT, SC and the laser metrology. We will present the adopted algorithms, and an overview of the structure of the developed software. The calibration of the wavelength scales of the FT and SC at the required accuracy presents specific difficulties that we will briefly discuss. Examples of the reduction of on-sky data obtained during the commissioning will also be presented.
Published: 2018

49. Image-plane fringe tracker for adaptive-optics assisted long baseline interferometry

Author: Barnaby Norris, Denis Defrere, John D. Monnier, Michael J. Ireland, Peter G. Tuthill, Julien Woillez, and F. Martinache
Subjects: Wavefront, Physics, Very Large Telescope, Offset (computer science), business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Image plane, 01 natural sciences, Exoplanet, 010309 optics, Interferometry, Optics, Path length, 0103 physical sciences, business, Adaptive optics, 010303 astronomy & astrophysics
Abstract: Accurate fringe tracking is essential for sensitive long-wavelength thermal background limited operation of the current Very Large Telescope Interferometry (VLTI) and future Planet Formation Imager (PFI) facilities. We present and simulate a dual fringe tracking and low-order adaptive optics concept based on a combination of non-redundant aperture interferometry and eigenphase in asymmetric pupil wavefront sensing. This scheme can acquire fringes at many wavelengths of path length offset between telescopes, even with moderate tilt offset and pupil shifts between beams. Once locked to fringes, our technique can also be used for simultaneous low-order wavefront sensing, and has near-optimum sensitivity where there is a dominant point-source image component. This concept is part of the Heimdallr visitor instrument currently being investigated for VLTI.
Published: 2018

50. VLTI status update: three years into the second generation

Author: Pierre van der Heyden, Roberto Abuter, Thibaut Guerlet, Andreas Glindemann, Yves Magnard, Frédéric Gonté, Andreas Haimerl, Andres Pino, Nicolas Schuhler, Richard Tamblay, Alexander Meister, Xavier Haubois, Pierre Haguenauer, Frederic Derie, Stefan Huber, Christian Stephan, Isabelle Percheron, Sébastien Poupar, Angela Cortes, Javier Reyes, F. Delplancke-Ströbele, J. Quentin, Roderick Dembet, Marcos Suarez, Julien Woillez, A. Ramirez, Christophe Verinaud, Mario Tapia, Luca Pasquini, Jean-Baptiste Le Bouquin, J. P. Kirchbauer, Emmanuel Aller-Carpentier, Pierre Bourget, R. Brast, José Antonio Abad, S. Rochat, Eloy Fuenteseca, Ralf Conzelmann, S. Guieu, A. Delboulbe, Pablo Barriga, Marcus Pavez, R. Frahm, Jean-Philippe Berger, Guillermo Valdes, Diego Del Valle, Sebastien Egner, Pascaline Darré, Antoine Mérand, R. Ridings, Christophe Dupuy, Lorenzo Pettazzi, Luigi Andolfato, Jerome Paufique, Lieselotte Jochum, Thomas Rivinius, Daniel Gaytan, Paul Bristow, Jean Francois Pirard, Pedro Mardones, Paul Jolley, Reinaldo Donoso, Fernando Salgado, Samuel Lévêque, Johann Kolb, Peter Krempl, Philippe Duhoux, Juan Osorio, Stephane Guisard, Gérard Zins, Willem-Jan de Wit, Jürgen Ott, Pavel Shchekaturov, Thibaut Moulin, Paul Lilley, Jean Louis Lizon, Laurent Pallanca, Andreas Förster, Norbert Hubin, Thanh Phan Duc, Johan Kosmalski, Markus Schöller, Luis Caniguante, Konrad R. W. Tristram, Jaime Alonso, Pablo Gutierrez, J. Beltran, Laurent Jocou, and Jaime Gonzales
Subjects: Interferometry, Upgrade, business.industry, Computer science, Astrometry, Telecommunications, business, Adaptive optics
Abstract: The near-infrared GRAVITY instrument has become a fully operational spectro-imager, while expanding its capability to support astrometry of the key Galactic Centre science. The mid-infrared MATISSE instrument has just arrived on Paranal and is starting its commissioning phase. NAOMI, the new adaptive optics for the Auxiliary Telescopes, is about to leave Europe for an installation in the fall of 2018. Meanwhile, the interferometer infrastructure has continuously improved in performance, in term of transmission and vibrations, when used with both the Unit Telescopes and Auxiliary Telescopes. These are the highlights of the last two years of the VLTI 2nd generation upgrade started in 2015.
Published: 2018

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