KINEMATICS AND VELOCITY ELLIPSOID OF THE SOLAR NEIGHBORHOOD WHITE DWARFS

To determine the velocity ellipsoid of the solar neighborhood white dwarfs, we use the space velocity components of stars. Two samples of white dwarfs are used, the 20 pc and 25 pc samples. Beside the two main samples, the solar velocity and velocity dispersions are calculated for four subsamples, namely BA, non - DA, hot and cool white dwarfs. A comparison between the results of the 20 pc sample and those of the 25 pc sample gives good agreement, while the comparison between the other subsamples gives poor agreement. The dependence of the velocity dispersions and solar velocity on the chemical composition and effective temperatures is discussed.