Kinematics of the Milky way from the statistical analysis of the Gaia Data Release 3

Petr Zavada, Karel Píška

Published 2023-08-21Version 1

By analyzing data from the Gaia Space Observatory, we have obtained precise basic characteristics of the collective motion of stars in a part of our galaxy. Our research is based on a statistical analysis of the motion of $33~146~122$ selected stars at a distance $\lesssim6$ kpc from the Sun. Up to this distance, Gaia provides high statistics of stars with well-measured proper motion and parallax needed to determine the corresponding transverse velocity with sufficient precision. We obtained the velocity of the Sun $\left( U_{\odot},V_{\odot},W_{\odot}\right) =(10.5\pm1,22.5\pm3,7.5\pm0.5)$ relative to a set of nearby stars and the rotation velocity of the galaxy at different radii. For the radius of the Sun's orbit, we obtained the velocity$\ V_{0}\approx225$ km/s. We have shown that the various kinematic characteristics and distributions, which depend on the position in the galaxy, can be very well described in the studied region by a simple Monte-Carlo simulation model based on five parameters in the galactocentric reference frame. The optimal values of these parameters were determined by comparison with the data.