1. The multichord stellar occultation on 2019 October 22 by the trans-Neptunian object (84922) 2003 VS$_2$
- Author
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Vara-Lubiano, M., Benedetti-Rossi, G., Santos-Sanz, P., Ortiz, J. L., Sicardy, B., Popescu, M., Morales, N., Rommel, F. L., Morgado, B., Pereira, C. L., Álvarez-Candal, A., Fernández-Valenzuela, E., Souami, D., Ilic, D., Vince, O., Bachev, R., Semkov, E., Nedelcu, D. A., Şonka, A., Hudin, L., Boaca, M., Inceu, V., Curelaru, L., Gherase, R., Turcu, V., Moldovan, D., Mircea, L., Predatu, M., Teodorescu, M., Stoian, L., Juravle, A., Braga-Ribas, F., Desmars, J., Duffard, R., Lecacheux, J., Camargo, J. I. B., Assafin, M., Vieira-Martins, R., Pribulla, T., Husárik, M., Sivanič, P., Pal, A., Szakats, R., Kiss, C., Alonso-Santiago, J., Frasca, A., Szabó, G. M., Derekas, A., Szigeti, L., Drozdz, M., Ogloza, W., Skvaruc, J., Ciabattari, F., Delincak, P., Di Marcantonio, P., Iafrate, G., Coretti, I., Baldini, V., Baruffetti, P., Klös, O., Dumitrescu, V., Mikuž, H., and Mohar, A.
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Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Solar and Stellar Astrophysics - Abstract
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 ${\Delta}$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 ${\theta}$ = 59${\deg} \pm$ 2${\deg}$ or its supplementary ${\theta}$ = 121${\deg} \pm$ 2${\deg}$, 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.
- Published
- 2022
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