Rotation velocities of white dwarfs determined from the Ca II K line

We determine projected rotation velocities in DAZ white dwarfs, for the first time using the rotational broadening of the Ca II K line. The results confirm previous findings that white dwarfs are very slow rotators, and set even more stringent upper limits of typically less than 10 km s^-1. The few exceptions include 3 stars known or suspected to be variable ZZ Ceti stars, where the line broadening is very likely not due to rotation. The results demonstrate that the angular momentum of the core cannot be preserved completely between main sequence and final stage.

Based in part on data obtained at the Paranal Observatory of the European Southern Observatory for programs 165.H-0588 and 167.D-0407.