Milky Way thin and thick disk kinematics with GAIA data

The evolution of galaxies has been studied for many years, but there is still no uniform scenario to describe our Galaxy and galaxies in the neighborhood as well as high-redshift galaxies. The work describes the basic ideas about the thick and thin disk of the Milky Way galaxy. A detailed analysis of the kinematics of the Milky Way disk in the vicinity of the Sun was performed using the GAIA catalogs EDR3 and Gaia DR3. To determine the local kinematics of the stellar disks of the Milky Way galaxy, we used a complete sample of red giant branch stars distributed in a cylinder centered on the Sun with a radius of 1 kpc and a height of 1 kpc. The kinematic properties of this sample were determined separately for each hemisphere of the Galaxy in search of possible asymmetries. The kinematical properties show the existence of two kinematically different components: a thin disk with average velocities V_R , V_Phi , V_Z about -1, -239.0 km/s, respectively, and velocity dispersions σ_R , σ_Phi , σ_Z at 31 , 20 and 11 km/s, as well as a thick disk with average velocity components of about +1, -225, 0 km/s and velocity dispersions of 49, 35, and 22 km/s. It was found that within the height of 500 pc above/below the galactic plane the stars of the thick disk constitute about half of the disk stars. So many stars of the red giant branch with thick disk kinematics could indicates the secular evolution scenario origin for the thick disk of the Milky Way galaxy. Then we explored the vertical structure of the Galactic disk by using a complete sample of main sequence stars distributed in cones within solid angle |b| <75 and up to distance of 2.5kpc. In order to extend the sample of stars with measured velocities we made an assumption than the proper motion aligned with the Galactic disk. The number density distribution along the vertical Z axis was build. We showed how rotational velocity V_Phi changes with the distance from the disk plane. We constructed dependence of contributions of the thin and thick disk components on the distance from the Galactic plane. According to our calculation the thick disk is more numerous then It is usually considered to be.