| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Auriga |
| Right ascension | 05h 20m 38.31s[2] |
| Declination | +30° 48′ 24.1″[2] |
| Apparent magnitude (V) | 15.56[2] |
| Characteristics | |
| Spectral type | DA[2] |
| U−Bcolor index | -0.59[citation needed] |
| B−Vcolor index | 0.22[2] |
| Variable type | Pulsating white dwarf |
| Astrometry | |
| Proper motion (μ) | RA: 54[2]mas/yr Dec.: −120[2]mas/yr |
| Distance | 170[3] ly (51 pc) |
| Absolute magnitude (MV) | 12 |
| Details | |
| Mass | 0.64 ± 0.03[4] M☉ |
| Surface gravity (log g) | 8.05[5] cgs |
| Temperature | 11980[5] K |
| Age | 1.2–1.7 billion[4] years |
| Other designations | |
| V361 Aurigae, GD 66,2MASS J05203829+3048239,WD 0517+30,EGGR 572,WD 0517+307 | |
| Database references | |
| SIMBAD | data |
GD 66 orV361 Aurigae is a 0.64solar mass (M☉)[4]pulsating white dwarf star located 170light years from Earth[3] in theAuriga constellation. The estimated cooling age of the white dwarf is 500 million years.[4] 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 themain sequence it had a mass of approximately 2.5M☉, which implies its lifetime was around 830 million years.[4] The total age of the star is thus estimated to be in the range 1.2 to 1.7 billion years.[4]
In 1983, Noël Dolezet al. discovered that GD 66 is a variable star, from photometric data obtained atHaute-Provence Observatory.[6] It was given itsvariable star designation, V361 Aurigae, in 1985.[7] The star is apulsating 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.[3] Observations with theSpitzer Space Telescope failed to directly detect the planet, which put an upper limit on the mass of 5–6 Jupiter masses.[4] Investigation of a separate pulsation mode revealed timing variations in antiphase with the variations in the originally-analysed pulsation mode.[8] 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.[9]
