GD 66 or V361 Aurigae is a 0.64 solar mass (M☉)[4] pulsating white dwarf star located 170 light years from Earth[3] in the Auriga 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 the main sequence it had a mass of approximately 2.5 M☉, 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]
| 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−B color index | -0.59[citation needed] |
| B−V color 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 | |
| Database references | |
| SIMBAD | data |
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.[3] 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.[4] Investigation of a separate pulsation mode revealed timing variations in antiphase with the variations in the originally-analysed pulsation mode.[6] 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.[7]
References
edit- ^ Fontaine, G.; Wesemael, F.; Bergeron, P.; Lacombe, P.; Lamontagne, R. (July 1985). "The demise of mode identification in the pulsating DA white dwarf GD 66". The Astrophysical Journal. 294: 339–344. Bibcode:1985ApJ...294..339F. doi:10.1086/163301. Retrieved 2 November 2021.
- ^ a b c d e f g "V* V361 Aur". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2008-12-19.
- ^ a b c Mullally, F.; et al. (2008). "Limits on Planets around Pulsating White Dwarf Stars". The Astrophysical Journal. 676 (1): 573–583. arXiv:0801.3104. Bibcode:2008ApJ...676..573M. doi:10.1086/528672. S2CID 123684051.
- ^ a b c d e f g Mullally, F.; et al. (2009). "Spitzer Planet Limits around the Pulsating White Dwarf GD66". The Astrophysical Journal. 694 (1): 327–331. arXiv:0812.2951. Bibcode:2009ApJ...694..327M. doi:10.1088/0004-637X/694/1/327. S2CID 16241754.
- ^ a b Bergeron, P.; et al. (2004). "On the Purity of the ZZ Ceti Instability Strip: Discovery of More Pulsating DA White Dwarfs on the Basis of Optical Spectroscopy". The Astrophysical Journal. 600 (1): 404–408. arXiv:astro-ph/0309483. Bibcode:2004ApJ...600..404B. doi:10.1086/379808. S2CID 16636294.
- ^ Hermes, James J. (2013). Complications to the Planetary Hypothesis for GD 66. AAS Meeting #221. American Astronomical Society. Bibcode:2013AAS...22142404H.
- ^ Hermes, J. J. (2012). 8 Years On: A Search for Planets Around Isolated White Dwarfs (PDF). Planets around Stellar Remnants. Archived from the original (PDF) on 2014-12-27.
External links
edit- V361 Aurigae Catalog
- WD 0517+307 Catalog
- Image GD 66