GD 358

GD 358 is a variable white dwarf star of the DBV type. Like other pulsating white dwarfs, its variability arises from non-radial gravity wave pulsations within itself.[6] GD 358 was discovered during the 1958–1970 Lowell Observatory survey for high proper motion stars in the Northern Hemisphere.[7] Although it did not have high proper motion, it was noticed that it was a very blue star, and hence might be a white dwarf.[8] Greenstein confirmed this in 1969.[9]

In 1968, Arlo U. Landolt discovered the first intrinsically variable white dwarf when he found that HL Tau 76 varied in brightness with a period of approximately 749.5 seconds, or 12.5 minutes.[10] By the middle of the 1970s, a number of additional variable white dwarfs had been found, but, like HL Tau 76, they were all white dwarfs of spectral type DA, with hydrogen-dominated atmospheres.[11][12][13] 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.[14]^{, p. L67.} Winget then searched for such stars and found that GD 358 was a variable DB, or DBV, white dwarf.[15] This was the first prediction of a class of variable stars before their observation.[16]^{, p. 89.} In 1985, this star was given the variable-star designation V777 Herculis, which is also another name for this class of variable stars.[17]^; [18]^{, p. 3525}