Pulsating white dwarf

[5][6] A subtype of DQV stars, with carbon-dominated atmospheres, has also been proposed,[7] and in May 2012, the first extremely low mass variable (ELMV) white dwarf was reported.

[8] These variables all exhibit small (1%–30%) variations in light output, arising from a superposition of vibrational modes with periods of hundreds to thousands of seconds.

[9] Early calculations suggested that white dwarfs should vary with periods around 10 seconds, but searches in the 1960s failed to observe this.

[11][12] The first variable white dwarf found was HL Tau 76; in 1965 and 1966, Arlo U. Landolt observed it to vary with a period of approximately 12.5 minutes.

[19] In 1982, calculations by Don Winget and his coworkers suggested that helium-atmosphere DB white dwarfs with surface temperatures around 19,000 K should also pulsate.

[21] Winget then searched for such stars and found that GD 358 was a variable DB, or DBV, white dwarf.

[30] A new class of white dwarfs, with spectral type DQ and hot, carbon-dominated atmospheres, has recently been discovered by Patrick Dufour, James Liebert and their coworkers.