Orbits and masses in the T Tauri system

Aims: We investigate the binary star T Tauri South, presenting the orbital parameters of the two components and their individual masses.
Methods: We combined astrometric positions from the literature with previously unpublished VLT observations. Model fits yield the orbital elements of T Tau Sa and Sb. We use T Tau N as an astrometric reference to derive an estimate for the mass ratio of Sa and Sb.
Results: Although most of the orbital parameters are not well constrained, it is unlikely that T Tau Sb is on a highly elliptical orbit or escaping from the system. The total mass of T Tau S is rather well constrained to 3.0^+0.15_-0.24~M_⊙. The mass ratio Sb:Sa is about 0.4, corresponding to individual masses of M_Sa = 2.1 ± 0.2 M_⊙ and M_Sb = 0.8 ± 0.1 M_⊙. This confirms that the infrared companion in the T Tauri system is a pair of young stars obscured by circumstellar material.

Based on observations collected at the European Southern Observatory, Chile, proposals number 070.C-0162, 072.C-0593,

074.C-0699, 074.C-0396, 078.C-0386, and 380.C-0179.