Beta Andromedae (β Andromedae, abbreviated Beta And, β And), officially named Mirach /ˈmræk/,[13][14] is a prominent star in the northern constellation of Andromeda. It is northeast of the Great Square of Pegasus and is theoretically visible to all observers north of 54° S. It is commonly used by stargazers to find the Andromeda Galaxy. The galaxy NGC 404, also known as Mirach's Ghost, is seven arc minutes away from Mirach.[15]

Beta Andromedae
Diagram showing star positions and boundaries of the Andromeda constellation and its surroundings
Cercle rouge 100%.svg
Location of β Andromedae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Andromeda
Right ascension  01h 09m 43.92388s[1]
Declination +35° 37′ 14.0075″[1]
Apparent magnitude (V) 2.05[2] (2.01 to 2.10)[3]
Spectral type M0 III[4]
U−B color index +1.96[2]
B−V color index +1.57[2]
V−R color index 0.9[5]
R−I color index +1.00[6]
Variable type Semiregular[3]
Radial velocity (Rv)0.06 ± 0.13[7] km/s
Proper motion (μ) RA: 175.90[1] mas/yr
Dec.: −112.20[1] mas/yr
Parallax (π)16.52 ± 0.56[1] mas
Distance197 ± 7 ly
(61 ± 2 pc)
Absolute magnitude (MV)–1.76[8]
Mass3–4[9] M
Radius100[10] R
Luminosity1,995[10] L
Surface gravity (log g)1.52[11] cgs
Temperature3,842[11] K
Metallicity [Fe/H]–0.05[11] dex
Rotational velocity (v sin i)7.2[10] km/s
Other designations
Mirach, Merach, Mirac, Mizar, β And, Beta Andromedae, Beta And, 43 Andromedae, 43 And, BD+34°198, FK5 42, GJ 53.3, GJ 9044, HD 6860, HIP 5447, HR 337, LTT 10420, NLTT 3848, SAO 54471, WDS 01097+3537A.[5][12]
Database references

This star has an average apparent visual magnitude of 2.05,[2] making it the brightest star in the constellation. The luminosity varies slightly from magnitude +2.01 to +2.10.[3] Based upon parallax measurements, it is roughly 197 light-years (60 parsecs) from the Sun.[1] Its apparent magnitude is reduced by 0.06 by extinction due to gas and dust along the line of sight.[7]


Beta Andromedae is a red giant with a stellar classification of M0 III.[4] Since 1943 the spectrum of this star has been one of the stable anchor points by which other stars are classified.[16] It is suspected of being a semiregular variable star whose apparent visual magnitude varies from +2.01 to +2.10.[3] At this stage of the star's evolution, the outer envelope has expanded to around 100 times the size of the Sun.[10] It is radiating 1995[10] times the luminosity of the Sun at an effective temperature of 3842 K.[11]



  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 c d NSV 414, database entry, table of suspected variable stars, Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.), N. N. Samus, O. V. Durlevich, et al., CDS ID II/250.
  4. ^ a b Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics, 11 (1): 29, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333
  5. ^ a b "bet And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved August 12, 2008.
  6. ^ HR 337, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line August 12, 2008.
  7. ^ a b Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430 (1): 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272
  8. ^ Elgarøy, Øystein; Engvold, Oddbjørn; Lund, Niels (March 1999), "The Wilson-Bappu effect of the MgII K line - dependence on stellar temperature, activity and metallicity", Astronomy and Astrophysics, 343: 222–228, Bibcode:1999A&A...343..222E
  9. ^ Mirach Archived December 16, 2008, at the Wayback Machine, Stars, Jim Kaler. Accessed on line August 13, 2008.
  10. ^ a b c d e Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209
  11. ^ a b c d Soubiran, C.; et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics, 480 (1): 91–101, arXiv:0712.1370, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788
  12. ^ a b c d e Allen, R. A. (1899), Star-names and Their Meanings, p. 36
  13. ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
  14. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  15. ^ Darling, David, "Mirach's Ghost (NGC 404)", The Internet Encyclopedia of Science, retrieved 2008-08-15
  16. ^ Garrison, R. F. (December 1993), "Anchor Points for the MK System of Spectral Classification", Bulletin of the American Astronomical Society, 25: 1319, Bibcode:1993AAS...183.1710G, retrieved 2012-02-04
  17. ^ p. 18, The Geography of the Heavens, Elijah Hinsdale Burritt, Hiram Mattison, and Henry Whitall, New York: Sheldon & Company, 1856.
  18. ^ Mirach, MSN Encarta. Accessed on line August 19, 2008. Archived 2009-10-31.
  19. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  20. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  21. ^ a b c George A.Davis Jr. (1971) Selected List of Star Names, p. 5.
  22. ^ ibid. p. 19.
  23. ^ Kunitsch, Paul; Smart, Tim (2006). A Dictionary of Modern Star names: A Short Guide to 254 Star Names and Their Derivations. Cambridge, Massachusetts: Sky Publishing Corp. p. 50. ISBN 978-1-931559-44-7.
  24. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日
  25. ^ p. 345, Exploring Ancient Skies: A Survey of Ancient and Cultural Astronomy, David H. Kelley, Eugene F. Milone, Anthony F. (FRW) Aveni, Berlin, Springer, 2011.
  26. ^ Rogers, J. H. (February 1998). "Origins of the ancient constellations: I. The Mesopotamian traditions". Journal of the British Astronomical Association. 108 (1): 9–28. Bibcode:1998JBAA..108....9R.

Further readingEdit

  • Davis Jr., G. A., (1971) Pronunciations, Derivations, and Meanings of a Selected List of Star Names, (rep.) Cambridge, Sky Publishing Corp.
  • Kunitzsch, P., (1959) Arabische Sternnamen in Europa
  • Kunitzsch. P., (ed.) (1990) Der Sternkatalog des Almagest, Band II

External linksEdit

Coordinates:   01h 09m 43.9236s, +35° 37′ 14.008″