WR 22

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WR 22
Carina Nebula around the Wolf–Rayet star WR 22.jpg
WR 22 in the Carina nebula
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Carina
Right ascension 10h 41m 17.5157s
Declination −59° 40′ 36.898″
Apparent magnitude (V) 6.42
Spectral type WN7h + O9III-V[1]
Apparent magnitude (U) 5.69
Apparent magnitude (B) 6.50
Apparent magnitude (J) 5.705
Apparent magnitude (H) 5.578
Apparent magnitude (K) 5.389
U−B color index -0.81
B−V color index 0.08
J−H color index 0.127
J−K color index 0.316
Variable type Eclipsing binary
Radial velocity (Rv) +33.0 km/s
Proper motion (μ) RA: -7.81 mas/yr
Dec.: 2.58 mas/yr
Parallax (π) 0.61 ± 0.52 mas
Distance 8,200[2] ly
(2,500[2] pc)
Absolute magnitude (MV) -4.65
Mass 78[2] + 21[3] M
Radius 23.7[2] + 9[3] R
Luminosity 2,000,000[2] + 100,000[3] L
Temperature 44,700[2] + 34,000[3] K
Age < 4 million years
Database references
Other designations
HR 4188, HD 92740, V429 Carinae, HIP 52308

WR 22, also known as V429 Carinae or HR 4188, is a Wolf-Rayet (WR) star in the constellation Carina. It is one of the most massive stars known, as well as one of the most luminous stars, and is also a bright x-ray source due to colliding winds with its less massive O class companion.


The mass of WR 22 has been determined accurately because it is an eclipsing binary, one of the most massive stars measured in this way rather than by assumptions about stellar evolution.[3]


High mass WR stars are young stars only just evolving away from the main sequence, rather than very old stars that have lost all their hydrogen. They show the WR characteristics of strong helium and nitrogen emission because they are strongly convective all the way to the core, so despite probably still burning hydrogen at the core they have dredged up heavier elements to the surface. Just a million or two years ago, WR22 would have been one of the hottest O type main sequence stars.[2]


  1. ^ Gagné, M.; Fehon, G.; Savoy, M. R.; Cartagena, C. A.; Cohen, D. H.; Owocki, S. P. (2012). "An X-Ray Survey of Colliding Wind Binaries". Proceedings of a Scientific Meeting in Honor of Anthony F. J. Moffat held at Auberge du Lac Taureau 465: 301. arXiv:1205.3510. Bibcode:2012ASPC..465..301G. 
  2. ^ a b c d e f g Gräfener, G.; Hamann, W.-R. (2008). "Mass loss from late-type WN stars and its Z-dependence. Very massive stars approaching the Eddington limit". Astronomy and Astrophysics 482 (3): 945. arXiv:0803.0866. Bibcode:2008A&A...482..945G. doi:10.1051/0004-6361:20066176. 
  3. ^ a b c d e Schweickhardt, J.; Schmutz, W.; Stahl, O.; Szeifert, Th.; Wolf, B. (1999). "Revised mass determination of the super massive Wolf-Rayet star WR 22". Astronomy and Astrophysics 347: 127. Bibcode:1999A&A...347..127S.