Orbits in the T Tauri triple system observed with SPHERE

TL;DR

This study provides new astrometric data and refined orbital parameters for the T Tauri triple system using SPHERE, leading to more accurate stellar masses and confirming the stability of the system's orbital configuration.

Contribution

The paper presents the first combined astrometric measurements with SPHERE and recalibrated data to derive precise orbits and masses for the T Tauri system, improving previous estimates.

Findings

Total mass of T Tauri S is 2.65 solar masses.

Mass ratio of Sb to Sa is 0.25.

No evidence for dramatic changes in the radio source path.

Abstract

We present new astrometric measurements of the components in the T Tauri system, and derive new orbits and masses. 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. 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 Msun. The mass ratio M_Sb:M_Sa is 0.25+/-0.03, which yields individual masses of M_Sa = 2.12+/-0.10 Msun and M_Sb = 0.53+/-0.06 Msun. 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 for the proposed dramatic change in its path.