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]

Planetary system[edit]

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.[1] 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.[3] However the discoverers note that the orbital configuration suggests that the objects formed as planets in a disc,[1] and the formation of planets above the deuterium fusion limit has been predicted by computer models of giant planet formation.[4] Further research has determined that the proposed arrangement is dynamically impossible.

See also[edit]


  1. ^ a b c 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. ^ "Definition of a "Planet"". Working Group on Extrasolar Planets (WGESP) of the International Astronomical Union. Retrieved 2009-07-04. 
  4. ^ Mordasini, C. et al. (2007). "Giant Planet Formation by Core Accretion". arXiv:0710.5667v1 [astro-ph].

External links[edit]

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