The multichord stellar occultation on 2019 October 22 by the trans-Neptunian object (84922) 2003 VS$_2$
Creators: name: Vara-Lubiano, M.
name: Benedetti-Rossi, G.
name: Santos-Sanz, P.
name: Ortiz, J. L.
name: Sicardy, B.
name: Popescu, M.
name: Morales, N.
name: Rommel, F. L.
name: Morgado, B.
name: Pereira, C. L.
name: Álvarez-Candal, A.
name: Fernández-Valenzuela, E.
name: Souami, D.
name: Ilic, D.
name: Vince, O.
name: Bachev, R.
name: Semkov, E.
name: Nedelcu, D. A.
name: Şonka, A.
name: Hudin, L.
name: Boaca, M.
name: Inceu, V.
name: Curelaru, L.
name: Gherase, R.
name: Turcu, V.
name: Moldovan, D.
name: Mircea, L.
name: Predatu, M.
name: Teodorescu, M.
name: Stoian, L.
name: Juravle, A.
name: Braga-Ribas, F.
name: Desmars, J.
name: Duffard, R.
name: Lecacheux, J.
name: Camargo, J. I. B.
name: Assafin, M.
name: Vieira-Martins, R.
name: Pribulla, T.
name: Husárik, M.
name: Sivanič, P.
name: Pal, A.
name: Szakats, R.
name: Kiss, C.
name: Alonso-Santiago, J.
name: Frasca, A.
name: Szabó, G. M.
name: Derekas, A.
name: Szigeti, L.
name: Drozdz, M.
name: Ogloza, W.
name: Skvaruc, J.
name: Ciabattari, F.
name: Delincak, P.
name: Di Marcantonio, P.
name: Iafrate, G.
name: Coretti, I.
name: Baldini, V.
name: Baruffetti, P.
name: Klös, O.
name: Dumitrescu, V.
name: Mikuž, H.
name: Mohar, A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We predicted, observed, and analyzed the multichord stellar occultation of the Second Gaia Data Release (Gaia DR2) source 3449076721168026624 (m$_v$ = 14.1 mag) by the plutino object 2003 VS$_2$ (hereafter, VS$_2$) on 2019 October 22. We also carried out photometric observations to derive the rotational light curve amplitude and rotational phase of VS$_2$ during the stellar occultation. Combining the results and assuming a triaxial shape, we derived the 3D shape of VS$_2$. Out of the 39 observatories involved in the observational campaign, 12 sites reported a positive detection; this makes it one of the best observed stellar occultations by a TNO so far. We obtained a rotational light curve amplitude of $Δ$m = 0.264 $\pm$ 0.017 mag, a mean area-equivalent diameter of D$_{A_{eq}}$ = 545 $\pm$ 13 km, and a geometric albedo of 0.134 $\pm$ 0.010. The best triaxial shape obtained for VS$_2$ has semiaxes a = 339 $\pm$ 5 km, b = 235 $\pm$ 6 km, and c = 226 $\pm$ 8 km. The derived aspect angle is $θ$ = 59$° \pm$ 2$°$ or its supplementary $θ$ = 121$° \pm$ 2$°$, depending on the north-pole position. The spherical-volume equivalent diameter is D$_{V_{eq}}$ = 524 $\pm$ 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 VS$_2$'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 VS$_2$ were detected.