Omicron2 Canis Majoris
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 07h 03m 01.47134s |
| Declination | −23° 49′ 59.8583″ |
| Apparent magnitude (V) | +2.93 to +3.08 |
| Characteristics | |
| Spectral type | B3 Ia |
| U−B color index | −0.778 |
| B−V color index | −0.107 |
| Variable type | α Cyg |
| Astrometry | |
| Radial velocity (Rv) | 53.88±4.04 km/s |
| Proper motion (μ) | RA: −1.335 mas/yr Dec.: +3.803 mas/yr |
| Parallax (π) | 0.8715±0.3319 mas |
| Distance | 3,700 ± 820 ly (1,135±250 pc) |
| Absolute magnitude (MV) | −7.3 |
| Details | |
| Mass | 24 M☉ |
| Radius | 65 R☉ |
| Luminosity | 220,000 L☉ |
| Surface gravity (log g) | 2.15 cgs |
| Temperature | 15,400 K |
| Rotational velocity (v sin i) | 35 km/s |
| Age | 7.4±1.0 Myr |
| Other designations | |
| ο2 Canis Majoris, 24 Canis Majoris, CD−23°4797, FK5 270, HD 53138, HIP 33977, HR 2653, SAO 172839 | |
| Database references | |
| SIMBAD | data |
Omicron2 Canis Majoris is a massive variable star in the constellation Canis Major. Its name is a Bayer designation that is Latinized from ο2 Canis Majoris, and abbreviated Omicron2 CMa or ο2 CMa. This star has an apparent visual magnitude around 3, making it visible to the naked eye and the sixth-to-seventh brightest star of the constellation, tied with Zeta Canis Majoris. Based upon a distance modulus of 10.2, it is about 3,600 light-years from Earth. It is drifting further away with a line of sight velocity of +55 km/s. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.