Kinematical structure of open clusters within 1 kpc by Gaia

Abstract

The work is based on proper motions, radial velocities, and absolute magnitudes of 56 open clusters located within 1 kpc. We classify those as a function of their distances into five groups (Freedman and Diaconis's rule) as well as a double frequency table may be achieved. For these groups, we calculated their velocity ellipsoid parameters VEPs, e.g. space velocity, dispersion velocity, elements of the Solar motion, and dispersion ratio (σ_{2}/σ_{1}).

For the first group of these open clusters with distances 98.717 ≤ r ≤ 310.078 pc, the dispersion ratio is in the range of 0.65-0.74, which is in a good agreement with that deduced by Oort. Finally, we have determined their luminosity and mass functions.