HW Virginis

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HW Virginis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Virgo
Right ascension 12h 44m 20.2367s
Declination −08° 40′ 16.837″
Apparent magnitude (V) 10.9
Distance 590 ± 65 ly
(181 ± 20 pc)
Spectral type sdB / M V
Other designations
HIP 62157
Database references

HW Virginis, abbreviated HW Vir, is an eclipsing binary system (of the Algol type) approximately 590 light-years away (based on the stellar properties and magnitudes: the Hipparcos trigonometric parallax measurement has too high an error value to be useful[1]) in the constellation of Virgo. The system comprises an eclipsing B-type subdwarf star and red dwarf star. The two stars orbit each other every 0.116795 days.[2]

Eclipse timing variations[edit]

Based on variations in the timing of the system's eclipses, in 2008 it was claimed that two giant planets were in orbit around the binary: one with a masses of 8.47 and 19.2 times the mass of Jupiter orbiting with periods of 9.1 and 15.8 years respectively.[1] The proposed system was later shown to be extremely unstable, with mean lifetimes less than 1000 years in the parameter space allowed by the uncertainties in the data.[3] An alternate, dynamically-stable orbital solution was proposed with a 14.3 Jupiter mass object on a 12-year orbit and an outer companion of 65 Jupiter masses on a 55-year orbit,[4] however it has been noted that the outer companion's orbital parameters are highly unconstrained, again casting doubt on the reality of this model.[3] The problems with modelling this system and the proposed planets orbiting several other post-common envelope binaries has led to the suggestion that the eclipse timing variations used to infer the existence of planets has a non-planetary origin.[5]

See also[edit]


  1. ^ a b Lee, Jae Woo; Kim, Seung-Lee; Kim, Chun-Hwey; Koch, Robert H.; Lee, Chung-Uk; Kim, Ho-Il; Park, Jang-Ho (2009). "The sdB+M Eclipsing System HW Virginis and its Circumbinary Planets". The Astronomical Journal 137 (2): 3181–3190. arXiv:0811.3807. Bibcode:2009AJ....137.3181L. doi:10.1088/0004-6256/137/2/3181. 
  2. ^ Kiss, L. L.; Csák, B.; Szatmáry, K.; Furész, G.; Sziládi, K. (2000). "Spectrophotometry and period analysis of the sdB eclipsing binary HW Virginis". Astronomy and Astrophysics 364: 199–204. arXiv:astro-ph/0010446. Bibcode:2000A&A...364..199K. 
  3. ^ a b Horner, J.; Hinse, T. C.; Wittenmyer, R. A.; Marshall, J. P.; Tinney, C. G. (2012). "A dynamical analysis of the proposed circumbinary HW Virginis planetary system". Monthly Notices of the Royal Astronomical Society 427 (4): 2812–2823. arXiv:1209.0608. Bibcode:2012MNRAS.427.2812H. doi:10.1111/j.1365-2966.2012.22046.x. 
  4. ^ Beuermann, K.; Dreizler, S.; Hessman, F. V.; Deller, J. (2012). "The quest for companions to post-common envelope binaries. III. A reexamination of HW Virginis". Astronomy & Astrophysics 543: id.A138. arXiv:1206.3080. Bibcode:2012A&A...543A.138B. doi:10.1051/0004-6361/201219391. 
  5. ^ Jonathan Horner, Robert Wittenmyer, Tobias Hinse, Jonathan Marshall, Alex Mustill (2014). "Wobbling Ancient Binaries - Here Be Planets?". arXiv:1401.6742 [astro-ph.EP]. 

External links[edit]

Coordinates: Sky map 12h 44m 20.2367s, −08° 40′ 16.837″