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 .