Epoch J2000 Equinox J2000
|Right ascension||05h 20m 38.31s|
|Declination||+30° 48′ 24.1″|
|Apparent magnitude (V)||15.56|
|U−B color index||-0.59|
|B−V color index||0.22|
|Variable type||Pulsating white dwarf|
|Proper motion (μ)|| RA: 54 mas/yr |
Dec.: −120 mas/yr
|Distance||170 ly |
|Absolute magnitude (MV)||12|
|Mass||0.64 ± 0.03 M☉|
|Surface gravity (log g)||8.05 cgs|
|Age||1.2–1.7 billion years|
GD 66 or V361 Aurigae is a 0.64 solar mass (M☉) pulsating white dwarf star located 170 light years from Earth in the Auriga constellation. The estimated cooling age of the white dwarf is 500 million years. 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. The total age of the star is thus estimated to be in the range 1.2 to 1.7 billion years.
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. 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. Investigation of a separate pulsation mode revealed timing variations in antiphase with the variations in the originally-analysed pulsation mode. 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.
- "V* V361 Aur". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2008-12-19.
- 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.
- Mullally, F.; et al. (2008). "Spitzer Planet Limits around the Pulsating White Dwarf GD66". The Astrophysical Journal. 694: 327. arXiv:0812.2951. Bibcode:2009ApJ...694..327M. doi:10.1088/0004-637X/694/1/327.
- 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.
- 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.