Kinematic Properties of Young Intermediate- and Low-Mass Stars from the Gaia DR2 Catalogue

TL;DR

This study analyzes the kinematic properties of young intermediate- and low-mass stars using Gaia DR2 data, providing updated parameters of Galactic rotation and demonstrating their very young age through low residual velocity dispersion.

Contribution

It offers new measurements of Galactic rotation parameters specifically for young pre-main-sequence stars, utilizing a large Gaia DR2 dataset with improved accuracy.

Findings

Galactic rotation parameters are precisely determined for young stars.

Residual velocity dispersion indicates the stars are extremely young.

The circular velocity near the Sun is measured as 230.7 km/s.

Abstract

We have studied the kinematic properties of young pre-main-sequence stars. We have selected these stars based on data from the Gaia DR2 catalogue by invoking a number of photometric infrared surveys. Using 4564 stars with parallax errors less than 20\%, we have found the following parameters of the angular velocity of Galactic rotation: $\Omega_0 =28.84\pm0.10$ km s$^{-1}$ kpc$^{-1}$, $\Omega^{'}_0=-4.063\pm0.029$ km s$^{-1}$ kpc$^{-2}$ and $\Omega^{''}_0=0.766\pm0.020$ km s$^{-1}$ kpc$^{-3}$, where the Oort constants are $A=16.25\pm0.33$ km s$^{-1}$ kpc$^{-1}$ and $B=-12.58\pm0.34$ km s$^{-1}$ kpc$^{-1}$. The circular rotation velocity of the solar neighborhood around the Galactic center is $V_0=230.7\pm4.4$ km s$^{-1}$ for the adopted Galactocentric distance of the Sun $R_0=8.0\pm0.15$ kpc. The residual velocity dispersion for the stars considered is shown to be low, suggesting that they are extremely young. The residual velocity dispersion averaged over three coordinates is $\sim$11 km s$^{-1}$ for Herbig Ae/Be stars and $\sim$7 km s$^{-1}$ for T Tauri stars.