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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 the star itself.^[8] GD 358 was discovered during the 1958–1970 Lowell Observatory survey for high proper motion stars in the Northern Hemisphere.^[9] 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.^[10] Greenstein confirmed this in 1969.^[11]

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.^[12] 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.^[13][14][15] 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.^{[16], p. L67.} Winget then searched for such stars and found that GD 358 was a variable DB, or DBV, white dwarf.^[1] This was the first prediction of a class of variable stars before their observation.^{[17], 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.^{[18]; [19], p. 3525}

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