Alpha Gruis
Alpha Gruis is the brightest star in the southern constellation of Grus. It is officially named Alnair; Alpha Gruis is the star's Bayer designation, which is Latinized from α Gruis and abbreviated α Gru. With an magnitude of 1.74, it is one of the brightest stars in the sky and one of the fifty-eight stars selected for celestial navigation. Alpha Gruis is a single, B-type main-sequence star located at a distance of 31 pc.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Grus |
| Pronunciation | /ælˈnɛər/ |
| Right ascension | 22h 08m 13.98473s |
| Declination | −46° 57′ 39.5078″ |
| Apparent magnitude (V) | +1.74 |
| Characteristics | |
| Spectral type | B6 V |
| U−B color index | −0.47 |
| B−V color index | −0.13 |
| Astrometry | |
| Radial velocity (Rv) | +11.8 km/s |
| Proper motion (μ) | RA: +126.69 mas/yr Dec.: −147.47 mas/yr |
| Parallax (π) | 32.29 ± 0.21 mas |
| Distance | 101.0 ± 0.7 ly (31.0 ± 0.2 pc) |
| Absolute magnitude (MV) | −0.72 |
| Details | |
| Mass | 4.0 M☉ |
| Radius | 3.4 R☉ |
| Luminosity | 520 L☉ |
| Surface gravity (log g) | 3.76±0.11 cgs |
| Temperature | 13,920 K |
| Metallicity [Fe/H] | −0.13±0.02 dex |
| Rotational velocity (v sin i) | 215 km/s |
| Age | 100 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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