WR 22
 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 |
| Characteristics | |
| 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 |
| Astrometry | |
| 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 |
| Details | |
| 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 | |
| SIMBAD | data |
| Other designations | |
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.
Mass
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]
Evolution
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]
References
- ↑ 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. Bibcode:2012ASPC..465..301G.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 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. Bibcode:2008A&A...482..945G. doi:10.1051/0004-6361:20066176.
- ↑ 3.0 3.1 3.2 3.3 3.4 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.
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