HW Virginis
Eclipsing binary with disputed planetary claims.
HW Virginis (HW Vir) is an eclipsing binary system of the Algol type, located about 563 light-years away in the constellation Virgo. It consists of a B-type subdwarf star and a red dwarf star that orbit each other every 0.116795 days. The system was identified as an eclipsing binary by John William Menzies and Freddy Marang in 1985.
Quick Facts
- Distance
- 563 light-years
- Constellation
- Virgo
- System type
- Eclipsing binary (Algol type)
- Stellar components
- B-type subdwarf and red dwarf
- Discoverers
- John William Menzies and Freddy Marang
- Discovery year
- 1985
Facts from the source article.
Eclipse timing variations
Variations in the timing of HW Virginis's eclipses led to a 2008 claim of two giant planets orbiting the binary, with masses 8.47 and 19.2 times Jupiter's mass and periods of 9.1 and 15.8 years. This proposed system was later shown to be extremely unstable, with mean lifetimes under 1000 years in the allowed parameter space. An alternative dynamically stable solution suggested a 14.3 Jupiter-mass object on a 12-year orbit and a 65 Jupiter-mass outer companion on a 55-year orbit, but the outer companion's parameters are highly unconstrained, again casting doubt. The difficulties in modeling this system and similar post-common envelope binaries have led to the suggestion that the eclipse timing variations have a non-planetary origin. As of 2018 and again in 2021, the variations were shown to be incompatible with all previous planetary system models, yet they cannot be explained by known stellar mechanisms either. Tentative astrometric evidence for a planet exists, and future Gaia data releases are predicted to confirm it.
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