Kinematics of T Tauri Stars Close to the Sun from the Gaia DR2 Catalogue

Abstract

The spatial and kinematic properties of a large sample of young T Tauri stars from the solar neighborhood 500 pc in radius have been studied. The following parameters of the position ellipsoid have been determined from the most probable members of the Gould Belt: its sizes are $350× 270× 87$ pc and it is oriented at an angle of $14^{\circ}± 1^{\circ}$ to the Galactic plane with a longitude of the ascending node of $297^{\circ}± 1^{\circ}$. An analysis of the motions of stars from this sample has shown that the residual velocity ellipsoid with principal semiaxes $σ_{1,2,3}=(8.87,5.58,3.03)±(0.10,0.20,0.04)$ km s${}^{-1}$ is oriented at an angle of $22± 1^{\circ}$ to the Galactic plane with a longitude of the ascending node of $298^{\circ}± 2^{\circ}$. It has been established that much of the expansion effect (kinematic $K$ effect) typical for Gould Belt stars, 5-6 km s${}^{-1}$ kpc${}^{-1}$, can be explained by the influence of a Galactic spiral density wave with a radial perturbation amplitude $f_R∼ 5$ km s${}^{-1}$.