Volume 663, July 2022
|Number of page(s)||17|
|Section||Planets and planetary systems|
|Published online||22 July 2022|
The multichord stellar occultation on 2019 October 22 by the trans-Neptunian object (84922) 2003 VS2★
Instituto de Astrofísica de Andalucía - Consejo Superior de Investigaciones Científicas,
Glorieta de la Astronomía S/N,
2 LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université de Paris, CNRS, 92190 Meudon, France
3 Laboratório Interinstitucional de e-Astronomia - LIneA & INCT do e-Universo, Rua Gal. José Cristino 77, Bairro Imperial de São Cristóvão, Rio de Janeiro (RJ), Brazil
4 UNESP - São Paulo State University, Grupo de Dinámica Orbital e Planetologia, Guaratinguetá, SP 12516-410, Brazil
5 Astronomical Institute of the Romanian Academy, 5 Cu¸itul de Argint, 040557 Bucharest, Romania
6 Instituto de Astrofísica de Canarias (IAC), C/Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
7 Observatório Nacional/MCTI, Rio de Janeiro (RJ), Brazil, Rua Gal. José Cristino 77, Bairro Imperial de São Cristóvão, Rio de Janeiro (RJ), Brazil
8 Florida Space Institute, UCF, 12354 Research Parkway, Partnership 1 building, Room 211, Orlando, USA
9 naXys, University of Namur, 8 Rempart de la Vierge, Namur 5000, Belgium
10 Department of astronomy, Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia
11 Humboldt Research Fellow, Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
12 Astronomical Observatory, Volgina 7, 11000 Belgrade, Serbia
13 Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences, Sofia, Bulgaria
14 ROASTERR-1 Observatory, L04 Cluj Napoca, Romania
15 Stardust Observatory, L13 Brasov, Romania
16 Astroclubul Bucureşti, Bucharest, Romania
17 Stardreams Observatory, L16 Vălenii de Monte, Romania
18 Romanian Academy - Cluj-Napoca Branch, Astronomical Observatory Cluj-Napoca, Romania
19 University of Craiova, Craiova, Romania
20 Institutul de Stiinte Spatiale (ISS), Atomistilor 409, C.P.: 23 Magurele 077125, Ilfov, Romania
21 Societatea Română pentru Astronomie Culturală (SRPAC), Timisoara, Romania
22 Federal University of Technology - Paraná (UTFPR/DAFIS), Curitiba, Brazil
23 Institut Polytechnique des Sciences Avancées IPSA, 63 boulevard de Brandebourg, 94200 Ivry-sur-Seine, France
24 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
25 Universidade Federal do Rio de Janeiro, Observatorio do Valongo, Rio de Janeiro, Brazil
26 Astronomical Institute of the Slovak Academy of Sciences, 059 60 Tatranska Lomnica, Slovakia
27 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, 1121 Budapest, Konkoly Thege Miklos ut 15-17, Hungary
28 Osservatorio Astrofísico di Catania (OACt-INAF), Via S. Sofia 78, 95123 Catania, Italy
29 ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, Szombathely, Hungary
30 MTA-ELTE Exoplanet Research Group, 9700 Szombathely, Szent Imre h. u. 112, Hungary
31 Mt. Suhora Observatory, Pedagogical University of Cracow Limanowa County, Poland
32 Isaac Newton Group of Telescopes, Santa Cruz de La Palma, Spain
33 Osservatorio Astronomico di Monte Agliale, Via Cune Motrone, Borgo a Mozzano, Italy
34 PDlink Observatory, Cadca, Slovakia
35 INAF - Osservatorio Astronomico di Trieste, Via Tiepolo 11, 34143 Trieste, Italy
36 Gruppo Astrofili Massesi, EAON, Massa, Italy
37 International Occultation Timing Association - European Section (IOTA/ES), Germany
38 Ia cu Stele, Bucharest, Romania
39 Crni Vrh Observatory, Crni Vrh nad Idrijo, Slovenia
40 Faculty of Mathematics and Physics, University of Ljubljana, Slovenia
41 Dark Sky Slovenia, Savlje 89, 1000 Ljubljana, Slovenia
Accepted: 7 April 2022
Context. Stellar occultations have become one of the best techniques to gather information about the physical properties of trans-Neptunian objects (TNOs), which are critical objects for understanding the origin and evolution of our Solar System.
Aims. The purpose of this work is to determine, with better accuracy, the physical characteristics of the TNO (84922) 2003 VS2 through the analysis of the multichord stellar occultation on 2019 October 22 and photometric data collected afterward.
Methods. We predicted, observed, and analyzed the multichord stellar occultation of the Second Gaia Data Release (Gaia DR2) source 3449076721168026624 (mυ = 14.1 mag) by the plutino object 2003 VS2 on 2019 October 22. We performed aperture photometry on the images collected and derived the times when the star disappeared and reappeared from the observing sites that reported a positive detection. We fit the extremities of such positive chords to an ellipse using a Monte Carlo method. We also carried out photometric observations to derive the rotational light curve amplitude and rotational phase of 2003 VS2 during the stellar occultation. Combining the results and assuming a triaxial shape, we derived the 3D shape of 2003 VS2.
Results. Out of the 39 observatories involved in the observational campaign, 12 sites, located in Bulgaria (one), Romania (ten), and Serbia (one), reported a positive detection; this makes it one of the best observed stellar occultations by a TNO so far. Considering the rotational phase of 2003 VS2 during the stellar occultation and the rotational light curve amplitude derived (Am = 0.264 ± 0.017 mag), we obtained a mean area-equivalent diameter of DAeq = 545 ± 13 km and a geometric albedo of 0.134 ± 0.010. By combining the rotational light curve information with the stellar occultation results, we derived the best triaxial shape for 2003 VS2, which has semiaxes a = 339 ± 5 km, b = 235 ± 6 km, and c = 226 ± 8 km. The derived aspect angle of 2003 VS2 is θ = 59° ± 2° or its supplementary θ = 121° ± 2°, depending on the north-pole position of the TNO. The spherical-volume equivalent diameter is DVeq = 524 ± 7 km. If we consider large albedo patches on its surface, the semi-major axis of the ellipsoid could be ~ 10 km smaller. These results are compatible with the previous ones determined from the single-chord 2013 and four-chord 2014 stellar occultations and with the effective diameter and albedo derived from Herschel and Spitzer data. They provide evidence that 2003 VS2’s 3D shape is not compatible with a homogeneous triaxial body in hydrostatic equilibrium, but it might be a differentiated body and/or might be sustaining some stress. No secondary features related to rings or material orbiting around 2003 VS2 were detected.
Key words: Kuiper belt objects: individual: 2003 VS2 / methods: observational / techniques: photometric
The photometric data used to obtain the rotational light curve of (84922) 2003 VS2 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/663/A121
© M. Vara-Lubiano et al. 2022
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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