GD 66
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Auriga |
| Right ascension | 05h 20m 38.31s[1] |
| Declination | +30° 48′ 24.1″[1] |
| Apparent magnitude (V) | 15.56[1] |
| Characteristics | |
| Spectral type | DA[1] |
| U−B color index | -0.59[citation needed] |
| B−V color index | 0.22[1] |
| Variable type | Pulsating white dwarf |
| Astrometry | |
| Proper motion (μ) | RA: 54[1] mas/yr Dec.: −120[1] mas/yr |
| Distance | 170[2] ly (51 pc) |
| Absolute magnitude (MV) | 12 |
| Details | |
| Mass | 0.64 ± 0.03[3] M☉ |
| Surface gravity (log g) | 8.05[4] cgs |
| Temperature | 11980[4] K |
| Age | 1.2–1.7 billion[3] years |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) |
|
GD 66 or V361 Aurigae is a 0.64 solar mass (M☉)[3] pulsating white dwarf star located 170 light years from Earth[2] in the Auriga constellation. The estimated cooling age of the white dwarf is 500 million years.[3] Models of the relationship between the initial mass of a star and its final mass as a white dwarf star suggest that when the star was on the main sequence it had a mass of approximately 2.5 M☉, which implies its lifetime was around 830 million years.[3] The total age of the star is thus estimated to be in the range 1.2 to 1.7 billion years.[3]
The star is a pulsating white dwarf of type DAV, with an extremely stable period. Small variations in the phase of pulsation led to the suggestion that the star was being orbited by a giant planet which caused the pulsations to be delayed due to the varying distance to the star caused by the reflex motion about the system's centre-of-mass.[2] Observations with the Spitzer Space Telescope failed to directly detect the planet, which put an upper limit on the mass of 5–6 Jupiter masses.[3] Investigation of a separate pulsation mode revealed timing variations in antiphase with the variations in the originally-analysed pulsation mode.[5] This would not be the case if the variations were caused by an orbiting planet, and thus the timing variations must have a different cause. This illustrates the potential dangers of attempting to detect planets by white dwarf pulsation timing.[6]
References
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- V361 Aurigae Catalog
- WD 0517+307 Catalog
- Image GD 66
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