Orbits in the T Tauri triple system observed with SPHERE^⋆

¹ University of Innsbruck, Institute for Astro- and Particle Physics, Technikerstr. 25, 6020 Innsbruck, Austria
e-mail: rainer.koehler@uibk.ac.at
² University of Vienna, Department of Astrophysics, Türkenschanzstr. 17 (Sternwarte), 1180 Vienna, Austria
e-mail: rainer.koehler@univie.ac.at
³ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
⁴ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁵ University of Graz, Institute for Physics/IGAM, NAWI Graz, Universitätsplatz 5/II, 8010 Graz, Austria
⁶ Kiel University, Institute of Theoretical Physics and Astrophysics, Leibnizstr. 15, 24098 Kiel, Germany
⁷ Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
⁸ Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército 441, Santiago, Chile
⁹ Millennium Nucleus “Protoplanetary Disks in ALMA Early Science”, Universidad de Chile, Casilla 36-D, Santiago, Chile

Received: 5 August 2015
Accepted: 7 December 2015

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_⊙. The mass ratio M_Sb:M_Sa is 0.25 ± 0.03, which yields individual masses of M_Sa = 2.12 ± 0.10 M_⊙ and M_Sb = 0.53 ± 0.06 M_⊙. 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.