Upsilon Carinae
 Location of υ Carinae (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Carina |
| Right ascension | 09h 47m 06.12170s |
| Declination | –65° 04′ 19.2267″ |
| Apparent magnitude (V) | 2.97 (+3.08/+6.25) |
| Characteristics | |
| Spectral type | A8 Ib + B7 III |
| U−B color index | +0.13 |
| B−V color index | +0.27 |
| Astrometry | |
| Radial velocity (Rv) | +14 km/s |
| Proper motion (μ) |
RA: –11.51 mas/yr Dec.: +4.71 mas/yr |
| Parallax (π) | 2.27 ± 0.28mas |
| Distance | approx. 1,400 ly (approx. 440 pc) |
| Absolute magnitude (MV) | −5.56 |
| Details | |
| υ Car A | |
| Mass | 13 M☉ |
| Surface gravity (log g) | 1.1 ± 0.3 cgs |
| Temperature | 7,600 ± 350 K |
| Age | 1.2 × 107 years |
| υ Car B | |
| Mass | 8 M☉ |
| Surface gravity (log g) | 3.3 ± 0.1 cgs |
| Temperature | 23,000 ± 1600 K |
| Other designations | |
| Database references | |
| SIMBAD | system |
| A | |
| B | |
Upsilon Carinae (υ Car, υ Carinae) is a double star in the southern constellation of Carina. It is part of the Diamond Cross asterism in southern Carina. The Upsilon Carinae system has a combined apparent magnitude of +2.97 and is approximately 1,400 light years (440 parsecs) from Earth.
In Chinese, 海石 (Hǎi Dàn), meaning Sea Rock, refers to an asterism consisting of υ Carinae, ε Carinae, ι Carinae, HD 83183 and HD 84810. Consequently, υ Carinae itself is known as 海石五 (Hǎi Dàn wǔ, English: the Fifth Star of Sea Rock.)
The primary component, υ Carinae A, has a stellar classification of A8 Ib, making it a supergiant star that has exhausted the hydrogen at its core and evolved away from its brief main sequence lifetime as an O9 V star. With an apparent magnitude of +3.08, it has an effective temperature of about 7,600 K, giving it a white hue. The companion, υ Carinae B, is a giant star with a classification of B7 III, although Mandrini and Niemela (1986) suggested it may be a subgiant star with a classification of B4–5 IV. The outer envelope of this star has an effective temperature of around 23,000 K, resulting in the blue-white hue of a B-type star.
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