SIMBAD references

We show that the proper motion of a pulsating white dwarf results in a secular change of the radial velocity of the star and consequently contributes to the observed dP/dt. The proper motion term is always positive and for a typical DAV white dwarf it is of the order of 10^–14-10^–15s.s^–1. This effect is thus comparable with the expected evolutionary period change in these stars due to their cooling, which also produces a positive period derivative, and has to be taken into account when the intrinsic dP/dt is to be properly determined from the observed period change