57 Geminorum
Star in the constellation Gemini
From Wikipedia, the free encyclopedia
57 Geminorum (57 Gem) is a yellow giant star in the constellation Gemini, with an apparent magnitude of 5.0. At a distance of about 179 light years, it has a luminosity about 29 times the Sun's. With an age of about 1.2 billion years, it has evolved away from the main sequence and expanded to seven times the width of the Sun.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Gemini |
| Right ascension | 07h 23m 28.511s[1] |
| Declination | +25° 03′ 01.91″[1] |
| Apparent magnitude (V) | 5.018[2] |
| Characteristics | |
| Spectral type | G8III[3] |
| U−B color index | +1.778[2] |
| B−V color index | +0.174[2] |
| Astrometry | |
| Radial velocity (Rv) | 5.43±0.13[1] km/s |
| Proper motion (μ) | RA: −66.676[1] mas/yr Dec.: −29.082[1] mas/yr |
| Parallax (π) | 18.1774±0.1459 mas[1] |
| Distance | 179 ± 1 ly (55.0 ± 0.4 pc) |
| Absolute magnitude (MV) | 1.66[4] |
| Details | |
| Mass | 2.2[5] M☉ |
| Radius | 7.1[1] R☉ |
| Luminosity | 29[1] L☉ |
| Surface gravity (log g) | 2.84[4] cgs |
| Temperature | 4,902[4] K |
| Metallicity [Fe/H] | 0.21[4] dex |
| Rotational velocity (v sin i) | 1.3[6] km/s |
| Age | 1.2[7] Gyr |
| Other designations | |
| A Geminorum, 57 Gem, HR 2808, HD 57727, BD+25°1660, HIP 35846, SAO 79352 | |
| Database references | |
| SIMBAD | data |
57 Geminorum is the star's Flamsteed designation. It also has the rarely-used Bayer designation A Geminorum.
The radial velocity of 57 Geminorum has been closely examined for indications that it may have orbiting exoplanets, but it shows a particularly stable radial velocity.[8][9]