![]() ![]() Alphard is the α star in the constellation of Hydra. |
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Observation data Epoch J2000 Equinox J2000 |
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Constellation | Hydra |
Right ascension | 09 |
Declination | –08° 39′ 30.969″ |
Apparent magnitude (V) | +2.00 |
Characteristics | |
Spectral type | K3 II-III |
U−B color index | +1.73 |
B−V color index | +1.44 |
Astrometry | |
Radial velocity (Rv) | -4.3 km/s |
Proper motion (μ) | RA: –14.49 mas/yr |
Parallax (π) | 18.40 ± 0.78mas |
Distance | 177 ± 8 ly (54 ± 2 pc) |
Absolute magnitude (MV) | −1.69 ± 0.09 |
Details | |
Mass | 3.03 ± 0.36M☉ |
Radius | 50.5 ± 4.0R☉ |
Luminosity | 780 ± 78L☉ |
Surface gravity (log g) | 1.54 |
Temperature | 4,120K |
Metallicity [Fe/H] | -0.06dex |
Rotation | 2,991 days |
Rotational velocity (v sin i) | 1.1 km/s |
Age | (4.2 ± 1.6) × 10 years |
Other designations | |
Alphard, Alfard, Alphart, Kalbelaphard, Cor Hydrae, 30 Hydrae, HR 3748, BD -08°2680, HD 81797, SAO 136871, FK5 354, HIP 46390.
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