The Trans-Neptunian Object (84922) 2003 VS2 through Stellar Occultations

We present results from three world-wide campaigns that resulted in the detections of two single-chord and one multi-chord stellar occultations by the plutino object (84922) 2003 VS2. From the single-chord occultations in 2013 and 2014 we obtained accurate astrometric positions for the object, while from the multi-chord occultation on 2014 November 7, we obtained the parameters of the best-fitting ellipse to the limb of the body at the time of occultation. We also obtained short-term photometry data for the body in order to derive its rotational phase during the occultation. The rotational light curve present a peak-to-peak amplitude of 0.141 +/- 0.009 mag. This allows us to reconstruct the 3D shape of the body, with principal semi-axes of a = 313.8 +/- 7.1 km, b = 265.5(-9.8)(+8.8) km, and c = 247.3(-43.6)(+26.6) km, which is not consistent with a Jacobi triaxial equilibrium figure. The derived spherical volume equivalent diameter of 548.3(-44.6)(+29.6) km is about 5% larger than the radiometric diameter of 2003 VS2 derived from Herschel data of 523 +/- 35 km, but still compatible with it within error bars. From those results we can also derive the geometric albedo (0.123(-0.014)(+0.015)) and, under the assumption that the object is a Maclaurin spheroid, the density rho = 1400(-300)(+1000) for the plutino. The disappearances and reappearances of the star during the occultations do not show any compelling evidence for a global atmosphere considering a pressure upper limit of about 1 microbar for a pure nitrogen atmosphere, nor secondary features (e.g., rings or satellite) around the main body.