57 Geminorum

This article is about A Geminorum. Not to be confused with α (alpha) Geminorum.
57 Geminorum
Location of 57 Geminorum (circled)
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]
Distance179 ± 1 ly
(55.0 ± 0.4 pc)
Absolute magnitude (MV)1.66[4]
Details
Mass2.2[5] M☉
Radius7.1[1] R☉
Luminosity29[1] L☉
Surface gravity (log g)2.84[4] cgs
Temperature4,902[4] K
Metallicity [Fe/H]0.21[4] dex
Rotational velocity (v sin i)1.3[6] km/s
Age1.2[7] Gyr
Other designations
A Geminorum, 57 Gem, HR 2808, HD 57727, BD+25°1660, HIP 35846, SAO 79352
Database references
SIMBADdata

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.

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]

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