2022ApJ...932...28V

We present a detailed analysis of kinematics of the Milky Way disk in the solar neighborhood using the Gaia DR3 catalog. To determine the local kinematics of the stellar disks of the Milky Way we use a complete sample of 278,228 red giant branch (RGB) stars distributed in a cylinder, centered at the Sun with a 1 kpc radius and half-height of 0.5 kpc. We determine separately the kinematical properties of RGB stars for each Galactic hemisphere in search of possible asymmetries. The kinematical properties of the RGB stars reveal the existence of two kinematically distinct components: the thin disk with mean velocities V_R, V_ph, V_Z of about -1, -239, 0 km s^–1, correspondingly, and velocity dispersions σ_R, σ_ph, σ_Z of 31, 20, and 11 km s^–1, and the Thick disk with mean velocity components of about +1, -225, 0 km s^–1, and velocity dispersions of 49, 35, and 22 km s^–1. We find that up to 500 pc in height above/below the Galactic plane, Thick disk stars comprise about half the stars of the disk. Such a high amount of RGB stars with Thick disk kinematics points at the secular evolution scenario origin for the Thick disk of the Milky Way.