Observation data Epoch J2000.0 Equinox J2000.0 ( ICRS) | |
---|---|
Constellation | Hercules |
Right ascension | 16h 47m 19.02s [2] |
Declination | +32° 28′ 31.9″ [2] |
Apparent magnitude (V) | 13.65 [2] |
Characteristics | |
Spectral type | DBV2 [3] |
B−V color index | -0.1 [2] |
Variable type | DBV [3] |
Astrometry | |
Proper motion (μ) |
RA: 6
[2]
mas/
yr Dec.: -162 [2] mas/ yr |
Parallax (π) | 23.2012 ± 0.0298 mas [4] |
Distance | 140.6 ± 0.2
ly (43.10 ± 0.06 pc) |
Absolute magnitude (MV) | +10.33 [5] |
Details | |
Mass | 0.584 [6] M☉ |
Radius | 0.0110 [7] R☉ |
Luminosity | 0.0676 [5] L☉ |
Surface gravity (log g) | 7.92 [7] cgs |
Temperature | 24,937 [7] K |
Other designations | |
EGGR 239,
V777 Her, PG 1645+325, WD 1645+325. | |
Database references | |
SIMBAD | data |
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
Observation data Epoch J2000.0 Equinox J2000.0 ( ICRS) | |
---|---|
Constellation | Hercules |
Right ascension | 16h 47m 19.02s [2] |
Declination | +32° 28′ 31.9″ [2] |
Apparent magnitude (V) | 13.65 [2] |
Characteristics | |
Spectral type | DBV2 [3] |
B−V color index | -0.1 [2] |
Variable type | DBV [3] |
Astrometry | |
Proper motion (μ) |
RA: 6
[2]
mas/
yr Dec.: -162 [2] mas/ yr |
Parallax (π) | 23.2012 ± 0.0298 mas [4] |
Distance | 140.6 ± 0.2
ly (43.10 ± 0.06 pc) |
Absolute magnitude (MV) | +10.33 [5] |
Details | |
Mass | 0.584 [6] M☉ |
Radius | 0.0110 [7] R☉ |
Luminosity | 0.0676 [5] L☉ |
Surface gravity (log g) | 7.92 [7] cgs |
Temperature | 24,937 [7] K |
Other designations | |
EGGR 239,
V777 Her, PG 1645+325, WD 1645+325. | |
Database references | |
SIMBAD | data |
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