Estimation of the Kinematic Age of the \(\boldsymbol{\beta}\) Pictoris Moving Group from Up-to-date Data

Abstract

The kinematics of about 40 single stars belonging to the \(\beta\) Pictoris moving group is studied. The age of the \(\beta\) Pictoris moving group is estimated from these stars with ground-based line-of-sight velocity determinations by two methods. Both estimates are kinematic. In the first method we considered the traceback trajectories of the stars, giving an estimate of \(t=13.2\pm 1.4\) Myr. In the second method, by analyzing the instantaneous velocities of the stars, we show that there is an expansion of the stellar system occurring in the Galactic \(xy\) plane. Based on this effect, we find the time interval elapsed from the beginning of the expansion of the \(\beta\) Pictoris moving group to the present day, \(t=20\pm 2\) Myr.