Eta Canis Majoris
Eta Canis Majoris (η Canis Majoris, abbreviated Eta CMa, η CMa), also named Aludra /əˈluːdrə, əˈljuːdrə/, is a star in the constellation of Canis Major. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 07h 24m 05.70228s |
| Declination | –29° 18′ 11.1798″ |
| Apparent magnitude (V) | 2.450 |
| Characteristics | |
| Spectral type | B5 Ia |
| U−B color index | −0.708 |
| B−V color index | −0.087 |
| Variable type | α Cyg |
| Astrometry | |
| Radial velocity (Rv) | 41.1 km/s |
| Proper motion (μ) | RA: −4.14 mas/yr Dec.: 5.81 mas/yr |
| Parallax (π) | 1.64 ± 0.40 mas |
| Distance | approx. 2,000 ly (approx. 600 pc) |
| Absolute magnitude (MV) | −7.0 |
| Details | |
| Mass | 18.19 M☉ |
| Radius | 54 R☉ |
| Luminosity | 135,000 - 174,000 L☉ |
| Surface gravity (log g) | 2.00 cgs |
| Temperature | 15,000 - 16,000 K |
| Rotational velocity (v sin i) | 40 km/s |
| Age | 8.3 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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