Orbits in the T Tauri triple system observed with SPHERE

Abstract

Aims. We present new astrometric measurements of the components in the T Tauri system and derive new orbits and masses.

Methods. T Tauri was observed during the science verification time of the new extreme adaptive optics facility SPHERE at the VLT. We combine the new positions with recalibrated NACO-measurements and data from the literature. Model fits for the orbits of T Tau Sa and Sb around each other and around T Tau N yield orbital elements and individual masses of the stars Sa and Sb.

Results. Our new orbit for T Tau Sa/Sb is in good agreement with other recent results, which indicates that enough of the orbit has been observed for a reliable fit. The total mass of T Tau S is 2.65 +/- 0.11 M-circle dot. The mass ratio M-Sb:M-Sa is 0.25 +/- 0.03, which yields individual masses of M-Sa = 2.12 +/- 0.10 M-circle dot and M-Sb = 0.53 +/- 0.06 M-circle dot. If our current knowledge of the orbital motions is used to compute the position of the southern radio source in the T Tauri system, then we find no evidence of the proposed dramatic change in its path.