Issue |
A&A
Volume 676, August 2023
|
|
---|---|---|
Article Number | A72 | |
Number of page(s) | 10 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202346749 | |
Published online | 09 August 2023 |
Constraints on (2060) Chiron’s size, shape, and surrounding material from the November 2018 and September 2019 stellar occultations
1
Federal University of Technology - Paraná (PPGFA/UTFPRCuritiba),
Rua Sete de Setembro,
3165,
Curitiba, PR, Brazil
e-mail: fribas@utfpr.edu.br
2
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot,
Sorbonne Paris Cité, 5 place Jules Janssen,
92195
Meudon, France
3
Laboratório Interinstitucional de e-Astronomia - LIneA & INCT do e-Universo,
R. General José Cristino 77, Bairro Imperial de São Cristóvão,
Rio de Janeiro, RJ, Brazil
4
Observatório Nacional/MCTIC,
R. General José Cristino 77, Bairro Imperial de São Cristóvão,
Rio de Janeiro, RJ, Brazil
5
Instituto de Astrofísica de Andalucía, IAA-CSIC,
Glorieta de la Astronomía s/n,
18008
Granada, Spain
6
Institut Polytechnique des Sciences Avancées IPSA,
63 boulevard de Brandebourg,
94200
Ivry-sur-Seine, France
7
Institut de Mécanique Céleste et de Calcul des Éphémérides, IMCCE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ Paris 06, Univ. Lille,
77 Av. Denfert-Rochereau,
75014
Paris, France
8
Planetary Science Institute,
1700 East Fort Lowell Road, Suite 106,
Tucson, AZ
87519, USA
9
Universidade Estadual de Ponta Grossa, O.A. - DEGEO,
Av. Carlos Cavalcanti, 4748,
Ponta Grossa
84030-900, PR, Brazil
10
Observatório do Valongo/UFRJ,
Ladeira Pedro Antonio 43,
Rio de Janeiro, RJ, Brazil
11
Institute of Physics, Federal University of Uberlândia,
Av. João Naves de Ávila - 2121 - Santa Mônica,
Uberlândia, MG, Brazil
12
European Asteroidal Occultation Network (EAON),
Rue de Mariembourg, 45,
5670
Dourbes, Belgium
13
International Occultation Timing Association - European Section (IOTA-ES),
Am Brombeerhag 13,
30459
Hannover, Germany
14
Observatoire de Nandrin, Société Astronomique de Liège,
Avenue des Platanes 17,
4000
Liège (Cointe), Belgium
15
Ciel et Espace,
17 rue Emile Deutsch de la Meurthe,
75014
Paris, France
16
University of the Free State,
205, Nelson Mandela Dr, Park West,
Bloemfontein,
9301, South Africa
17
Observatorio astronómico de Forcarei,
As Casetas, EP-7001, 18,
36556
Forcarei, Pontevedra, Spain
18
Planetarium Ludiver,
1700, rue de la Libértion, Tonneville,
50460
La Hauge, France
19
Landessternwarte, Universität Heidelberg,
Königstuhl 12,
69117
Heidelberg, Germany
Received:
26
April
2023
Accepted:
12
June
2023
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.
Key words: comets: individual: (2060) Chiron / minor planets, asteroids: general / planets and satellites: rings / Kuiper belt: general
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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