Astronomy:Mirach

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Short description: Star in the constellation Andromeda
Mirach
Andromeda IAU.svg
Red circle.svg
Location of Mirach (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Andromeda
Right ascension  01h 09m 43.91s[1]
Declination +35° 37′ 13.8″[1]
Apparent magnitude (V) 2.067[1] (2.01 to 2.10)[2]
Characteristics
Evolutionary stage Asymptotic giant branch[3]
Spectral type M0 III[4][5]
U−B color index +1.96[6]
B−V color index +1.57[6]
V−R color index 0.9[7]
R−I color index +1.00[8]
Variable type Semiregular[2]
Astrometry
Radial velocity (Rv)0.06±0.13[9] km/s
Proper motion (μ) RA: 175.90[10] mas/yr
Dec.: −112.20[10] mas/yr
Parallax (π)16.52 ± 0.56[10] mas
Distance199.27±9.27 ly
(61.12±2.84 pc)
Absolute magnitude (MV)−1.76[11]
Details[5]
Mass2.49[12][5] M☉
Radius86.4 R☉
Luminosity1,675 L☉
Surface gravity (log g)0.541 cgs
Temperature3,802 K
Metallicity [Fe/H]−0.03 dex
Rotation<7900 d (<21.6 years)
Rotational velocity (v sin i)6 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, 9044, HD 6860, HIP 5447, HR 337, SAO 54471, PPM 66010, WDS 01097+3537A, LTT 10420, NLTT 3848[7][13]
Database references
SIMBADdata

Mirach/ˈmaɪræk/,[14][15] Bayer designation Beta Andromedae, Latinized from β Andromedae, is a prominent star in the northern constellation of Andromeda. It is northeast of the Great Square of Pegasus and is potentially visible to all observers north of latitude 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 arcminutes away from Mirach.[16]

This star has an apparent visual magnitude of around 2.07,[1] varying between 2.01 and 2.10,[2] which at times makes it the brightest star in the constellation. Based upon parallax measurements, it is roughly 197 light-years (60 parsecs) from the Sun.[10] Its apparent magnitude is reduced by 0.06 by extinction due to gas and dust along the line of sight.[9] The star has a negligible radial velocity of 0.1 km/s,[9] but with a relatively large proper motion, traversing the celestial sphere at 0.208″·yr−1.[17]

Properties

A light curve for Mirach, plotted from Hipparcos data[18]

Mirach is a single[19] red giant with a stellar classification of M0 III,[4] and is currently on the asymptotic giant branch of its evolution.[3] Since 1943 the spectrum of this star has been one of the stable anchor points by which other stars are classified.[20] It is suspected of being a semiregular variable star whose apparent visual magnitude varies from +2.01 to +2.10.[2] At this stage of the star's evolution, the outer envelope has expanded to around 100 times the size of the Sun.[21] It is radiating 1,995[21] times the luminosity of the Sun at an effective temperature of 3,842 K.[22]

Nomenclature

Beta Andromedae is the star's Bayer designation. It had the traditional name of Mirach, and its variations, such as Mirac, Mirar, Mirath, Mirak, etc. (the name is spelled Merach in Burritt's The Geography of the Heavens),[23] which come from the star's description in the Alfonsine Tables of 1521 as super mizar. Here, mirat is a corruption of the Arabic مئزر mīzar "girdle", which appeared in a Latin translation of the Almagest.[13] This word refers to Mirach's position at the left hip of the princess Andromeda.[24] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[25] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[26] included a table of the first two batches of names approved by the WGSN; which included Mirach for this star.

Mirach is listed in the Babylonian MUL.APIN as KA.MUSH.I.KU.E, meaning "the Deleter" (the alternative star is α Cas).[27] Medieval astronomers writing in Arabic called Mirach Janb al-Musalsalah (English: The Side of the Chained (Lady)); it was part of the 28th manzil (Arabian lunar mansion) Baṭn al-Ḥūt, the Belly of the Fish, or Qalb al-Ḥūt, the Heart of the Fish.[13][28] The star has also been called Cingulum and Ventrale.[13] This al-Ḥūt was an indigenous Arabic constellation, not the Western "Northern Fish" part of the constellation Pisces.[28] These names are not from the Arabic marāqq, loins, because it was never called al-Marāqq in Arabian astronomy.[28] Al Rishā', the Cord (of the well-bucket), on al-Sūfī's star map. It is origin of the proper name Alrescha for Alpha Piscium.[13][29]

In Chinese, 奎宿 (Kuí Sù), meaning Legs, refers to an asterism consisting of Mirach (β Andromedae), η Andromedae, 65 Piscium, ζ Andromedae, ε Andromedae, δ Andromedae, π Andromedae, ν Andromedae, μ Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, φ Piscium, χ Piscium and ψ1 Piscium. Consequently, the Chinese name for β Andromedae itself is 奎宿九 (Kuí Sù jiǔ, English: the Ninth Star of Legs).[30]

The people of Micronesia named this star Kyyw, meaning "The Porpoise", and this was used as one of the names of the months in Micronesia.[31]

Substellar companion

A 2023 study detected radial velocity variations in Mirach (HD 6860), showing evidence of a substellar companion, likely a brown dwarf.[32]

The Mirach planetary system[32]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥28.26+2.05
−2.17 MJ 		2.03±0.01 663.87+4.61
−4.31 		0.28+0.10
−0.09 		— —

References

  1. ↑ 1.0 1.1 1.2 1.3 "HD 6860 | NASA Exoplanet Archive". https://exoplanetarchive.ipac.caltech.edu/overview/HD%206860%20b#planet_HD-6860-b_collapsible. 
  2. ↑ 2.0 2.1 2.2 2.3 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.
  3. ↑ 3.0 3.1 Eggen, Olin J. (July 1992), "Asymptotic giant branch stars near the sun", Astronomical Journal 104 (1): 275–313, doi:10.1086/116239, Bibcode: 1992AJ....104..275E. 
  4. ↑ 4.0 4.1 Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics 11 (1): 29, doi:10.1146/annurev.aa.11.090173.000333, Bibcode: 1973ARA&A..11...29M 
  5. ↑ 5.0 5.1 5.2 Lee, Byeong-Cheol; Do, Hee-Jin; Park, Myeong-Gu; Lim, Beomdu; Choi, Yeon-Ho; Koo, Jae-Rim; Bang, Tae-Yang; Oh, Hyeong-Ill et al. (2023-10-01). "Long-period radial velocity variations of nine M red giants. The detection of substellar companions around HD 6860 and HD 112300". Astronomy and Astrophysics 678: A106. doi:10.1051/0004-6361/202243725. ISSN 0004-6361. https://ui.adsabs.harvard.edu/abs/2023A&A...678A.106L. 
  6. ↑ 6.0 6.1 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode: 1966CoLPL...4...99J 
  7. ↑ 7.0 7.1 "bet And". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=bet+And. 
  8. ↑ 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.
  9. ↑ 9.0 9.1 9.2 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, doi:10.1051/0004-6361:20041272, Bibcode: 2005A&A...430..165F 
  10. ↑ 10.0 10.1 10.2 10.3 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V 
  11. ↑ 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 
  12. ↑ Dehaes, S. et al. (September 2011), "Structure of the outer layers of cool standard stars", Astronomy & Astrophysics 533: A107, doi:10.1051/0004-6361/200912442, Bibcode: 2011A&A...533A.107D 
  13. ↑ 13.0 13.1 13.2 13.3 13.4 Allen, R. A. (1899), Star-names and Their Meanings, p. 36, https://books.google.com/books?id=5xQuAAAAIAAJ 
  14. ↑ 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. 
  15. ↑ "IAU Catalog of Star Names". http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt. 
  16. ↑ Darling, David, Mirach's Ghost (NGC 404), http://www.daviddarling.info/encyclopedia/M/Mirachs_Ghost.html, retrieved 2008-08-15 
  17. ↑ Lépine, Sébastien; Shara, Michael M. (March 2005), "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", The Astronomical Journal 129 (3): 1483–1522, doi:10.1086/427854, Bibcode: 2005AJ....129.1483L. 
  18. ↑ "/ftp/cats/more/HIP/cdroms/cats". Strasbourg astronomical Data Center. https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats. 
  19. ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  20. ↑ 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, http://www.astro.utoronto.ca/~garrison/mkstds.html, retrieved 2012-02-04 
  21. ↑ 21.0 21.1 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, doi:10.1088/0004-6256/135/1/209, Bibcode: 2008AJ....135..209M 
  22. ↑ 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, doi:10.1051/0004-6361:20078788, Bibcode: 2008A&A...480...91S 
  23. ↑ p. 18, The Geography of the Heavens, Elijah Hinsdale Burritt, Hiram Mattison, and Henry Whitall, New York: Sheldon & Company, 1856.
  24. ↑ Mirach, MSN Encarta. Accessed on line August 19, 2008. Archived 2009-10-31.
  25. ↑ "IAU Working Group on Star Names (WGSN)". https://www.iau.org/science/scientific_bodies/working_groups/280/. 
  26. ↑ "Bulletin of the IAU Working Group on Star Names, No. 1". http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf. 
  27. ↑ 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. 
  28. ↑ 28.0 28.1 28.2 George A.Davis Jr. (1971) Selected List of Star Names, p. 5.
  29. ↑ 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. 
  30. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日
  31. ↑ 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.
  32. ↑ 32.0 32.1 Lee, Byeong-Cheol et al. (October 2023). "Long-period radial velocity variations of nine M red giants: The detection of sub-stellar companions around HD 6860 and HD 112300". Astronomy & Astrophysics 678: A106. doi:10.1051/0004-6361/202243725. Bibcode: 2023A&A...678A.106L. 

Further reading

  • 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 links

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



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