Constraints on (2060) Chiron’s size, shape, and surrounding material from the November 2018 and September 2019 stellar occultations
Year: 2023
Type: article
Abstract: Context. After the discovery of rings around the largest known Centaur object, (10199) Chariklo, we carried out observation campaigns of stellar occultations produced by the second-largest known Centaur object, (2060) Chiron, to better characterize its physical properties and presence of material on its surroundings. Aims. We aim to provide constraints on (2060) Chiron’s shape for the first time using stellar occultations. We investigate the detectability of material previously observed in its vicinity using the 2018 occultation data obtained from South Africa Astronomical Observatory (SAAO). Methods. We predicted and successfully observed two stellar occultations by Chiron. These observations were used to constrain its size and shape by fitting elliptical limbs with equivalent surface radii in agreement with radiometric measurements. We also obtained the properties of the material observed in 2011 with the same technique used to derive Chariklo’s ring properties in our previous works, used to obtain limits on the detection of secondary events in our 2018 observation. Results. Constraints on the (2060) Chiron shape are reported for the first time. Assuming an equivalent radius of Requiv = 105−7+6 km, we obtained a semi-major axis of a = 126 ± 22 km. Considering Chiron’s true rotational light curve amplitude and assuming it has a Jacobi equilibrium shape, we were able to derive a 3D shape with a semi-axis of a = 126 ± 22 km, b = 109 ± 19 km, and c = 68 ± 13 km, implying in a volume-equivalent radius of Rvol= 98 ± 17 km. We determined the physical properties of the 2011 secondary events around Chiron, which may then be directly compared with those of Chariklo rings, as the same method was used. Data obtained from SAAO in 2018 do not show unambiguous evidence of the proposed rings, mainly due to the large sampling time. Meanwhile, we discarded the possible presence of a permanent ring similar to (10199) Chariklo’s C1R in optical depth and extension. Conclusions. Using the first multi-chord stellar occultation by (2060) Chiron and considering it to have a Jacobi equilibrium shape, we derived its 3D shape, implying a density of 1119 ± 4 kg m−3. New observations of a stellar occultation by (2060) Chiron are needed to further investigate the material’s properties around Chiron, such as the occultation predicted for September 10, 2023.
Source: Astronomy and Astrophysics
Authors: F. Braga-Ribas, C. L. Pereira, B. Sicardy, J. L. Ortiz, J. Desmars, A. Sickafoose, M. Emilio, B. Morgado, G. Margoti, F. L. Rommel, J. I. B. Camargo, M. Assafin, R. Vieira-Martins, A. R. Gomes-Júnior, P. Santos-Sanz, N. Morales, M. Kretlow, J. Lecacheux, F. Colas, R. Boninsegna, O. Schreurs, J. L. Dauvergne, E. Fernandez, H. J. van Heerden, H. González, D. Bihel, F. Jankowsky
Institutions: Universidade Tecnológica Federal do Paraná, Centre National de la Recherche Scientifique, Université Paris Sciences et Lettres, Observatoire de Paris, Sorbonne Université, Sorbonne Paris Cité, Laboratoire d’études spatiales et d’instrumentation en astrophysique, Laboratório Interinstitucional de e-Astronomia, National Observatory, Instituto de Astrofísica de Andalucía, Université de Lille, Institut de Mécanique Céleste et de Calcul des Éphémérides, Institut Polytechnique des Sciences Avancées, Planetary Science Institute, Universidade Estadual de Ponta Grossa, Universidade Federal do Rio de Janeiro, Valongo Observatory, Universidade Federal de Uberlândia, University of the Free State, Heidelberg University
Language: English
Topic: Astro and Planetary Science
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,623
Funders: European Space Agency, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Junta de Andalucía, Horizon 2020 Framework Programme, Agencia Estatal de Investigación
Awards: G1175115578, G1581564621, G1840770272, G187588942, G1972605707, G2262748287, G2713276326, G278595929, G2791710201, G2816488996, G2863668859, G29316538, G300979063, G3154116105, G3201898775, G321761023, G34346518, G3480869486, G3483367168, G3626710213, G425668148, G4574909456, G463062595, G4740277510, G4750726618, G5080475149, G5165349198, G5251085409, G5293599680, G5669043247, G5779771523, G5894067328, G611330818, G6676276723, G683931746, G7084143925, G7391010604, G751615522, G8033781863, G8089911369, G8440677993, G863151887, G8800772453, G8920101981
OpenAlex ID: W4382877282