The outer orbit of the triple star T Tauri

Abstract

The T Tauri's triple system of young stars (WDS 04220+1932=Hip 20390) was discovered in 1983. Since that time, a lot of articles are devoted to the study of the physical properties of the stars of this system. Our work is dedicated to astrometric study of this triple system using the apparent motion parameters (AMP) method. The orbit of the inner pair $ SaSb $ with a period of 27 years is now well known \citep{schef20}. The total mass $M_{Sa+Sb}=2.49 M_\odot$ if to use parallax from Gaia DR3 \citep{G2022}. Two orbits of the outer pair N-S are obtained on the basis of published high-precision homogeneous observations on the Keck~1 and VLT telescopes, and one of them is almost circular orbit. For a circular orbit, orbital elements and dynamic parallax can be calculated for a given mass using only apparent motion parameters. This is what made it possible to compare dynamic parallax with high-precision one from the Gaia DR3 catalog and to calculate the components masses depending on the mass of the internal subsystem: $M_{N}=2.4\pm 0.2~M_\odot$, $M_{Sa}=2.09\pm 0.05~M_\odot$, $M_{Sb}=0.40\pm 0.05~M_\odot$. Limits for the orbital period are also estimated: $500\leq {P}\leq {700}$ ~ years.