Mu Andromedae

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Mu Andromedae
Diagram showing star positions and boundaries of the Andromeda constellation and its surroundings
Cercle rouge 100%.svg
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]
Spectral type A5 V[3]
U−B color index +0.15[2]
B−V color index +0.12[2]
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[1] mas
Distance130 ± 4 ly
(40 ± 1 pc)
Absolute magnitude (MV)+0.86[5]
Mass2.0[6] M
Radius2.4[6] R
Luminosity21[6] L
Surface gravity (log g)3.99[6] cgs
Temperature7,959[7] K
Metallicity [Fe/H]+0.03[7] dex
Rotational velocity (v sin i)75[8] km/s
Age600[9] Myr
Other designations
μ Andromedae, μ And, Mu And, 37 Andromedae, BD+37°175, FK5 33, HD 5448, HIP 4436, HR 269, SAO 54281.
Database references

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.[10]

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.[6] The star is radiating about 21[6] times the luminosity of the Sun from its outer envelope at an effective temperature of 7,959 K,[7] giving it the characteristic white glow of an A-type star.[11] It is estimated to be about 600 million years old,[9] with a relatively high projected rotational velocity of 75 km/s.[8]


In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of μ Andromedae, η Andromedae, 65 Piscium, ζ Andromedae, ε Andromedae, δ Andromedae, π Andromedae, ν Andromedae, β Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, φ Piscium, χ Piscium and ψ¹ Piscium. Consequently, μ Andromedae itself is known as 奎宿八 (Kuí Sù bā, English: the Eighth Star of Legs.)[12]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
  3. ^ a b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
  4. ^ Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington D.C., Bibcode:1953GCRV..C......0W.
  5. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  6. ^ a b c d e f Malagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars", Astronomy and Astrophysics Supplement Series, 85 (3): 1015–1019, Bibcode:1990A&AS...85.1015M.
  7. ^ a b c Gardiner, R. B.; Kupka, F.; Smalley, B. (July 1999), "Testing convection theories using Balmer line profiles of A, F, and G stars", Astronomy and Astrophysics, 347: 876–890, Bibcode:1999A&A...347..876G.
  8. ^ a b Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
  9. ^ a b Rieke, G. H.; et al. (February 2005), "Decay of Planetary Debris Disks", The Astrophysical Journal, 620 (2): 1010–1026, Bibcode:2005ApJ...620.1010R, CiteSeerX, doi:10.1086/426937.
  10. ^ Reddy, Francis (2011), Celestial Delights: The Best Astronomical Events Through 2020 (3rd ed.), Springer, p. 236, ISBN 1461406099.
  11. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16.
  12. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日

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