HW Virginis

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HW Virginis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Virgo
Right ascension 12h 44m 20.23731s[1]
Declination −08° 40′ 16.8338″[1]
Apparent magnitude (V) 10.69[2]
Distance 590 ± 65 ly
(181 ± 20 pc)
Spectral type sdB / dM[3]
Other designations
HIP 62157, BD−08°3477, 2MASS J12442024-0840168
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[4]) 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.[5]

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.[4] 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.[6] 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,[7] however it has been noted that the outer companion's orbital parameters are highly unconstrained, again casting doubt on the reality of this model.[6] 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.[8]

See also[edit]


  1. ^ a b Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862. 
  3. ^ Almeida, L. A.; Jablonski, F.; Tello, J.; Rodrigues, C. V. (2012). "A photometric and spectroscopic study of NSVS 14256825: The second sdOB+dM eclipsing binary". Monthly Notices of the Royal Astronomical Society. 423: 478. arXiv:1203.1266Freely accessible. Bibcode:2012MNRAS.423..478A. doi:10.1111/j.1365-2966.2012.20891.x. 
  4. ^ 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:0811.3807Freely accessible. Bibcode:2009AJ....137.3181L. doi:10.1088/0004-6256/137/2/3181. 
  5. ^ 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/0010446Freely accessible. Bibcode:2000A&A...364..199K. 
  6. ^ 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:1209.0608Freely accessible. Bibcode:2012MNRAS.427.2812H. doi:10.1111/j.1365-2966.2012.22046.x. 
  7. ^ 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:1206.3080Freely accessible. Bibcode:2012A&A...543A.138B. doi:10.1051/0004-6361/201219391. 
  8. ^ Jonathan Horner; Robert Wittenmyer; Tobias Hinse; Jonathan Marshall; Alex Mustill (2014). "Wobbling Ancient Binaries - Here Be Planets?". arXiv:1401.6742Freely accessible [astro-ph.EP]. 

External links[edit]

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