Epoch J2000.0 Equinox J2000.0 (ICRS)
|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|
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) 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.
|This section's factual accuracy may be compromised due to out-of-date information. (April 2013)|
In addition, the system has two substellar companions in orbit around the binary: the inner companion HW Virginis c has a mass at least 8.47 times the mass of Jupiter and takes just over 9 years to complete an orbit. The outer companion HW virginis b takes 15.8 years to complete an orbit and has a mass at least 19.2 times Jupiter's mass. According to the definition used by the International Astronomical Union's Working Group on Extrasolar Planets, the inner companion would be classified as a planet, while the outer companion would be classified as a brown dwarf. However the discoverers note that the orbital configuration suggests that the objects formed as planets in a disc, and the formation of planets above the deuterium fusion limit has been predicted by computer models of giant planet formation. Further research has determined that the proposed arrangement is dynamically impossible.
- 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.
- 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.
- "Definition of a "Planet"". Working Group on Extrasolar Planets (WGESP) of the International Astronomical Union. Retrieved 2009-07-04.
- Mordasini, C. et al. (2007). "Giant Planet Formation by Core Accretion". arXiv:0710.5667v1 [astro-ph].
- "Notes for star HW Vir". The Extrasolar Planets Encyclopaedia. Retrieved 25 November 2008.
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