Alphard
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 09h 27m 35.2433s |
| Declination | −08° 39′ 30.969″ |
| Apparent magnitude (V) | +2.00 |
| Characteristics | |
| Evolutionary stage | Giant star |
| Spectral type | K3IIIa |
| U−B color index | +1.73 |
| B−V color index | +1.45 |
| Astrometry | |
| Radial velocity (Rv) | −4.3 km/s |
| Proper motion (μ) | RA: −14.49 mas/yr Dec.: 33.25 mas/yr |
| Parallax (π) | 18.40±0.78 mas |
| Distance | 177 ± 8 ly (54 ± 2 pc) |
| Absolute magnitude (MV) | −1.743±0.032 |
| Details | |
| Mass | 3.2±0.32 M☉ |
| Radius | 57.59+0.63 −0.64 R☉ |
| Luminosity | 971+154 −133 L☉ |
| Luminosity (visual, LV) | 426 L☉ |
| Surface gravity (log g) | 1.77 cgs |
| Temperature | 4,117±18 K |
| Metallicity [Fe/H] | −0.12 dex |
| Rotation | 2,991 days |
| Rotational velocity (v sin i) | 1.1 km/s |
| Age | 420±160 Myr |
| Other designations | |
| Alphard, Alfard, Alphart, Kalbelaphard, Cor Hydrae, 30 Hydrae, HR 3748, BD−08°2680, HD 81797, SAO 136871, FK5 354, HIP 46390 | |
| Database references | |
| SIMBAD | data |
Alphard (/ˈælfɑːrd/) is the brightest star in the constellation of Hydra. It has the Bayer designation Alpha Hydrae, which is that is Latinized from α Hydrae, and abbreviated Alpha Hya or α Hya. It is a giant star, cooler than the Sun but larger and more luminous. It is about 177 light-years away.