Omega Carinae
 Location of ω Carinae (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Carina |
| Right ascension | 10h 13m 44.21739s |
| Declination | –70° 02′ 16.4563″ |
| Apparent magnitude (V) | 3.29 |
| Characteristics | |
| Spectral type | B8 IIIe |
| U−B color index | –0.285 |
| B−V color index | –0.083 |
| Astrometry | |
| Radial velocity (Rv) | +7.0 km/s |
| Proper motion (μ) |
RA: -36.01 mas/yr Dec.: +7.09 mas/yr |
| Parallax (π) | 9.54 ± 0.09mas |
| Distance | 342 ± 3 ly (104.8 ± 1.0 pc) |
| Details | |
| Surface gravity (log g) | 3.581 cgs |
| Temperature | 13,275 K |
| Rotational velocity (v sin i) | 245 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Omega Carinae (ω Car, ω Carinae) is a star in the constellation Carina. With a declination greater than 70 degrees south of the celestial equator, it is the most southerly of the bright stars of Carina (third-magnitude or brighter), and it is part of a southern asterism known as the Diamond Cross. This star has an apparent visual magnitude of 3.3 and is located at a distance of about 342 light-years (105 parsecs) from Earth.
Omega Carinae has a stellar classification of B8 IIIe, which places it among a category known as Be stars that display emission lines of hydrogen their spectrum. Omega Carinae is a shell star, having a circumstellar disk of gas surrounding its equator. The luminosity class of III indicates it has evolved into a giant star, having exhausted the hydrogen at its core and left the main sequence. The effective temperature of 13,275 K in its outer envelope is what gives this star the blue-white hue that is characteristic of B-type stars.
This star is rotating rapidly with a projected rotational velocity of 245 km s−1, which gives a lower limit to the star's azimuthal velocity along the equator. The critical equatorial velocity, at which the star would begin to break up, is 320 km s−1. The star's axis of rotation is inclined by an estimated angle of 70.8° to the line of sight from the Earth.
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