The kinematics of white dwarfs from the SDSS DR12

We use the Sloan Digital Sky Survey Data Release 12, which is the largest availablewhite dwarf catalogue to date, to study the evolution of the kinematical properties of the pop-ulation of white dwarfs of the Galactic disk. We derive masses, ages, photometric distances andradial velocities for all white dwarfs with hydrogen-rich atmospheres. For those stars for whichproper motions from the USNO-B1 catalogue are available, the three-dimensional componentsof the velocity are obtained. This subset of the original sample comprises 20,247 stars, makingit the largest sample of white dwarfs with measured three-dimensional velocities. The volumeprobed by our sample is large, allowing us to obtain relevant kinematical information. In partic-ular, our sample extends from a Galactocentric radial distanceRG=7.8 to 9.3 kpc, and verticaldistances from the Galactic plane ranging fromZ=+0.5to–0.5kpc.