Mu Andromedae

μ Andromedae
Location of μ Andromedae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 00h 56m 45.21211s[1]
Declination +38° 29′ 57.6380″[1]
Apparent magnitude (V) 3.87[2]
Characteristics
Spectral type A5 V[3]
U−B color index +0.15[2]
B−V color index +0.12[2]
Astrometry
Radial velocity (Rv)+7.6[4] km/s
Proper motion (μ) RA: +153.48[1] mas/yr
Dec.: +36.49[1] mas/yr
Parallax (π)25.14 ± 0.86 mas[1]
Distance130 ± 4 ly
(40 ± 1 pc)
Absolute magnitude (MV)+0.86[5]
Orbit[6]
Period (P)550.7 ± 0.2 d
Semi-major axis (a)46.66 ± 0.06 mas
Eccentricity (e)0.8405 ± 0.0009
Inclination (i)52.5 ± 0.3°
Longitude of the node (Ω)−17.6 ± 0.2°
Periastron epoch (T)55765.45 ± 0.04 MJD
Argument of periastron (ω)
(secondary)		168.9 ± 0.3°
Semi-amplitude (K1)
(primary)		11.1 ± 0.5 km/s
Details
Mass2.0[7] M☉
Radius2.4[7] R☉
Luminosity21[7] L☉
Surface gravity (log g)3.99[7] cgs
Temperature7,959[8] K
Metallicity [Fe/H]+0.03[8] dex
Rotational velocity (v sin i)75[9] km/s
Age600[10] Myr
Other designations
μ Andromedae, μ And, Mu And, 37 Andromedae, BD+37°175, FK5 33, HD 5448, HIP 4436, HR 269, SAO 54281, PPM 65785
Database references
SIMBADdata

Mu Andromedae (Mu And, μ Andromedae, μ And) is the Bayer designation for a star in the northern constellation of Andromeda. It has an apparent visual magnitude of 3.87,[2] making it readily visible to the naked eye. Based upon parallax measurements, it is approximately 130 light-years (40 parsecs) from Earth.[1] In the constellation, the star is situated about halfway between the bright star Mirach to the southwest and the Andromeda Galaxy (M31) to the northeast.[11]

The spectrum of this star matches a stellar classification of A5 V,[3] indicating that it is an A-type main sequence star. It has double the mass of the Sun and 2.4 times the Sun's radius.[7] The star is radiating about 21[7] times the luminosity of the Sun from its outer envelope at an effective temperature of 7,959 K,[8] giving it the characteristic white glow of an A-type star.[12] It is estimated to be about 600 million years old,[10] with a relatively high projected rotational velocity of 75 km/s.[9] Mu Andromedae has recently been found to be a binary system. The two stars orbit each other every 550.7 days.[6]

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