Studying the Kinematics of the Stellar Association TW Hya from Current Data

TL;DR

This study analyzes the kinematics of the TW Hya stellar association, estimating its age through trajectory analysis and velocity expansion, revealing insights into its dynamical state and age.

Contribution

It provides new kinematic estimates of TW Hya's age using trajectory integration and velocity expansion analysis, offering a comprehensive dynamical characterization.

Findings

Estimated age of 4.9 ± 1.2 Myr from trajectory analysis.

Estimated age of 9.5 ± 1.1 Myr from expansion analysis.

Determined residual velocity ellipsoid axes: (5.25, 1.84, 0.35) km/s.

Abstract

The kinematics of the young stellar association near the Sun TW Hya is studied. Kinematic estimates of the age of this association were obtained in two ways. The first method -- analysis of stellar trajectories integrated back in time -- gave an estimate of the age $t=4.9\pm1.2$ Myr. The second was to analyze the instantaneous velocities of stars and showed that there is a volume expansion of the stellar system with an angular velocity coefficient $K_{xyz}=103\pm12$ km s$^{-1}$ kpc$^{-1}$. Based on this effect, the time interval that passed from the beginning of the expansion of the TW Hya association to the present moment was found, $t=9.5\pm1.1$ Myr. The following principal semi-axes of the residual velocity ellipsoid are determined: $\sigma_{1,2,3}=(5.25,1.84,0.35)\pm(0.34,0.63,0.26)$ km s$^{-1}$.