A stellar occultation by the transneptunian object (50000) Quaoar observed by CHEOPS

Author(s): B. E. Morgado, G. Bruno, A. R. Gomes-Júnior, I. Pagano, B. Sicardy, Andrea Fortier, J. Desmars, Pierre F. L. Maxted, F. Braga-Ribas, D. Queloz, Sergio G. Sousa, J. L. Ortiz, Alexis Brandeker, A. Collier Cameron, C. L. Pereira, H. G. Florén, N. Hara, D. Souami, Kate G. Isaak, G. Olofsson, P. Santos-Sanz, Thomas G. Wilson, J. Broughton, Y. Alibert, Roi Alonso, G. Anglada, T. Bárczy, D. Barrado, Susana C. C. Barros, Wolfgang Baumjohann, M. Beck, T. Beck, Willy Benz, Nicolas Billot, Xavier Bonfils, C. Broeg, J. Cabrera, Sébastien Charnoz, Szilard Csizmadia, Melvyn B. Davies, M. Deleuil, Laetitia Delrez, Olivier D.S. Demangeon, Brice-Olivier Demory, D. Ehrenreich, A. Erikson, Luca Fossati, Malcolm Fridlund, D. Gandolfi, Michael Gillon, M. Güdel, K. Heng, S. Hoyer, L. L. Kiss, Jacques Laskar, A. Lecavelier Des Etangs, Monika Lendl, C. Lovis, Demetrio Magrin, L. Marafatto, V. Nascimbeni, R. Ottensamer, E. Pallé, Gisbert Peter, D. Piazza, G. Piotto, Don Pollacco, Roberto Ragazzoni, Nicola Rando, Francesco Ratti, H. Rauer, C. Reimers, I. Ribas, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M.S. Smith, M. Steller, G. M. Szabó, Nicolas Thomas, S. Udry, V. Van Grootel, N. A. Walton, K. Westerdorff
Abstract: Context. Stellar occultation is a powerful technique that allows the determination of some physical parameters of the occulting object. The result depends on the photometric accuracy, the temporal resolution, and the number of chords obtained. Space telescopes can achieve high photometric accuracy as they are not affected by atmospheric scintillation. Aims. Using ESA's CHEOPS space telescope, we observed a stellar occultation by the transneptunian object (50000) Quaoar. We compare the obtained chord with previous occultations by this object and determine its astrometry with sub-milliarcsecond precision. Also, we determine upper limits to the presence of a global methane atmosphere on the occulting body. Methods. We predicted and observed a stellar occultation by Quaoar using the CHEOPS space telescope. We measured the occultation light curve from this dataset and determined the dis- and reappearance of the star behind the occulting body. Furthermore, a ground-based telescope in Australia was used to constrain Quaoar's limb. Combined with results from previous works, these measurements allowed us to obtain a precise position of Quaoar at the occultation time. Results. We present the results obtained from the first stellar occultation by a transneptunian object using a space telescope orbiting Earth; it was the occultation by Quaoar observed on 2020 June 11. We used the CHEOPS light curve to obtain a surface pressure upper limit of 85 nbar for the detection of a global methane atmosphere. Also, combining this observation with a ground-based observation, we fitted Quaoar's limb to determine its astrometric position with an uncertainty below 1.0 mas. Conclusions. This observation is the first of its kind, and it shall be considered as a proof of concept of stellar occultation observations of transneptunian objects with space telescopes orbiting Earth. Moreover, it shows significant prospects for the James Webb Space Telescope.
Organisation(s): Department of Astrophysics
External organisation(s): Universidade Federal do Rio de Janeiro, Observatório Nacional/MCT, Laboratório Interinstitucional de e-Astronomia (LIneA), INAF-Osservatorio Astrofisico di Catania, Universidade Federal de Uberlândia, Universidade Estadual Paulista „Júlio de Mesquita Filho“, Université de recherche Paris Sciences et Lettres, Universität Bern, Institut Polytechnique des Sciences Avancées, Keele University, Universidade Tecnólogica Federal do Paraná, Eidgenössische Technische Hochschule Zürich, University of Cambridge, Universidade do Porto, Instituto de Astrofísica de Andalucía (CSIC), Stockholm University, University of St. Andrews, Université de Genève, Université Côte d'Azur, Université de Namur, Science and Operations Department - Science Division (SCI-SC), Reedy Creek Observatory, Royal Astronomical Society of New Zealand, Institute of Astrophysics of the Canary Islands, University of La Laguna, Spanish National Research Council (CSIC), Universitat Autònoma de Barcelona , Institute of Space Studies of Catalonia (IEEC), Admatis Ltd., European Space Astronomy Centre (ESA), Österreichische Akademie der Wissenschaften (ÖAW), University of Grenoble Alpes, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Université de Paris, Lund University, Aix-Marseille Université, Université de Liège, Leiden University, Chalmers University of Technology, University of Turin, University of Warwick, Eötvös Loránd Research Network, Eötvös Loránd University Budapest, Université Paris VI - Pierre-et-Marie-Curie, Osservatorio Astronomico, University of Padova, Technische Universität Berlin, Freie Universität Berlin (FU)
Journal: Astronomy and Astrophysics
Volume: 664
No. of pages: 9
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/202244221
Publication date: 08-2022
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics, 103038 Space exploration
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/0ff5f48a-a47e-45c5-9cc8-bc6c3e6d0f62

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