WR 22

WR 22

WR 22 in the Carina nebula
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Carina
Right ascension	10h 41m 17.51590s[1]
Declination	−59° 40′ 36.8957″[1]
Apparent magnitude (V)	6.42[2]
Characteristics
Spectral type	WN7h + O9III-V[3]
Apparent magnitude (U)	5.68[2]
Apparent magnitude (B)	6.50[2]
Apparent magnitude (J)	5.705[4]
Apparent magnitude (H)	5.578[4]
Apparent magnitude (K)	5.389[4]
U−B color index	−0.82[2]
B−V color index	0.08[2]
J−H color index	0.127[4]
J−K color index	0.316[4]
Variable type	Eclipsing binary[5]
Astrometry
Radial velocity (Rv)	−28.00[6] km/s
Proper motion (μ)	RA: −7.321[7] mas/yr Dec.: 3.091[7] mas/yr
Parallax (π)	0.3953 ± 0.0348 mas[7]
Distance	8,300 ± 700 ly (2,500 ± 200 pc)
Absolute magnitude (MV)	−6.73 + −4.44[5]
Orbit[8]
Primary	WR
Companion	O
Period (P)	80.336 days[9]
Semi-major axis (a)	330 R☉
Eccentricity (e)	0.598
Inclination (i)	83.5[9]°
Argument of periastron (ω) (secondary)	268.2°
Semi-amplitude (K1) (primary)	70.6 km/s
Semi-amplitude (K2) (secondary)	190.0 km/s
Details
WR
Mass	49 - 75[10] M☉
Radius	22.65[10] R☉
Luminosity	1,905,000[10] L☉
Temperature	44,700[10][11] K
O
Mass	25.7[12] M☉
Radius	11[12] R☉
Luminosity	130,000[12] L☉
Temperature	33,000[12] K
Age	2.2[11] Myr
Other designations
CD−59°3221, HR 4188, HD 92740, V429 Carinae, HIP 52308
Database references
SIMBAD	data

WR 22, also known as V429 Carinae or HR 4188, is an eclipsing binary star system in the constellation Carina. The system contains a Wolf-Rayet (WR) star that is one of the most massive and most luminous stars known, and is also a bright X-ray source due to colliding winds with a less massive O class companion. Its eclipsing nature and apparent magnitude make it very useful for constraining the properties of luminous hydrogen-rich WR stars.^[9]

In 1978, Anthony Moffat and Wilhelm Seggewiss announced that the star's brightness varies.^[13] Eclipses were first detected by Luis A. Balona et al. in 1989.^[14] It received its variable star designation, V429 Carinae, in 1980.^[15]