  Recently, some hot DA-type white dwarfs have been proposed to plausibly be
escaping members of the Hyades. We used hydrogen Balmer lines to measure the
radial velocities of seven such stars and confirm that three, and perhaps two
others, are/were indeed cluster members and one is not. The other candidate
Hyad is strongly magnetic and its membership status remains uncertain. The
photospheres of at least one quarter of field white dwarf stars are "polluted"
by elements heavier than helium that have been accreted. These stars are
orbited by extended planetary systems that contain both debris belts and major
planets. We surveyed the seven classical single Hyades white dwarfs and the
newly identified (escaping) Hyades white dwarfs and found calcium in the
photosphere of LP 475-242 of type DBA (now DBAZ), thus implying the presence of
an orbiting planetary system. The spectrum of white dwarf GD 31, which may be,
but probably is not, an escaping member of the Hyades, displays calcium
absorption lines; these originate either from the interstellar medium or, less
likely, from a gaseous circumstellar disk. If GD 31 was once a Hyades member,
then it would be the first identified white dwarf Hyad with a cooling age >340
Myr.

Solar and Stellar Astrophysics