Beta Andromedae
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(Redirected from Merach)
This article is about the star. For the target drones, see Galileo Mirach 150 and Galileo Mirach 26.
 Location of β Andromedae (circled) |
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| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
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|---|---|
| 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] |
| Characteristics | |
| 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] |
| Astrometry | |
| 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 |
| Distance | 197 ± 7 ly (61 ± 2 pc) |
| Absolute magnitude (MV) | –1.76[8] |
| Details | |
| Mass | 3–4[9] M☉ |
| Radius | 100[10] R☉ |
| Luminosity | 1,995[10] L☉ |
| Surface gravity (log g) | 1.52[11] |
| Temperature | 3,842[11] K |
| Metallicity [Fe/H] | –0.05[11] dex |
| Rotational velocity (v sin i) | 7.2[10] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Beta Andromedae (Beta And, β And, β Andromedae) is the Bayer designation for a prominent star in the northern constellation of Andromeda. It has the traditional name Mirach, which is also spelled Merach, Mirac, Mirak.[12] β Andromedae is located northeast of the Great Square of Pegasus and is theoretically visible to all observers north of 54° S. The galaxy NGC 404, also known as Mirach's Ghost, is visible seven arc-minutes away.[13]
This star has an average apparent visual magnitude of 2.05,[2] which makes it the brightest star in the constellation. However, the luminosity varies slightly from magnitude +2.01 to +2.10.[3] Based upon parallax measurements, it is located at a distance of roughly 197 light-years (60 parsecs) from Earth.[1] The apparent magnitude of this star is reduced by 0.06 from extinction caused by the gas and dust along the line of sight.[7]
Contents |
Properties [edit]
Beta Andromedae is a red giant with a stellar classification of M0 III.[4] Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[14] 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 1,995[10] times the luminosity of the Sun at an effective temperature of 3,842 K.[11]
Naming and etymology [edit]
- The name Mirach, and its variations, such as Mirac, Mirar, Mirath, Mirax, etc. (the name is spelled Merach in Burritt's The Geography of the Heavens)[15] come from the star's description in the Alfonsine Tables of 1521 as super mizar.[12] Here, mirat is a corruption of the Arabic ميزر mīzar "girdle", which appeared in a Latin translation of the Almagest.[12] This word refers to Mirach's position at the left hip of the princess Andromeda.[16]
- Medieval astronomers writing in Arabic called β Andromedae Janb al-Musalsalah (English: The Side of the Chained (Lady)); it was part of the 26th manzil (Arabian lunar mansion) Batn al-Hũt, the Belly of the Fish, or Qalb al-Hũt, the Heart of the Fish.[12][17] The star has also been called Cingulum and Ventrale.[12] This al-Hũt was an indigenous Arabic constellation, not the Western "Northern Fish" part of the constellation Pisces.[17] These names are not from the Arabic marãqq, loins, because it was never called al-Marãqq in Arabian astronomy.[17] Al Rishã', the Cord (of the well-bucket), on al-Sũfĩ's star map. It is origin of the proper name Alrescha for Alpha Piscium.[12][18][19]
- In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of 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, β Andromedae itself is known as 奎宿九 (Kuí Sù jiǔ, English: the Ninth Star of Legs.)[20]
- The people of Micronesia named this star as Kyyw "The Porpoise", and become once of Micronesian month name.[21]
- Mirach is listed in MUL.APIN as KA.MUSH.I.KU.E, meaning "the Deleter" (the alternative star is α Cas).[22]
References [edit]
- ^ 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
- ^ 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
- ^ 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.
- ^ 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
- ^ a b NAME MIRACH -- Variable Star, database entry, SIMBAD. Accessed on line August 12, 2008.
- ^ 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.
- ^ 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
- ^ 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
- ^ Mirach, Stars, Jim Kaler. Accessed on line August 13, 2008.
- ^ 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
- ^ 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
- ^ a b c d e f g Allen, R. A. (1899), Star-names and Their Meanings, p. 36
- ^ Darling, David, "Mirach's Ghost (NGC 404)", The Internet Encyclopedia of Science, retrieved 2008-08-15
- ^ 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
- ^ p. 18, The Geography of the Heavens, Elijah Hinsdale Burritt, Hiram Mattison, and Henry Whitall, New York: Sheldon & Company, 1856.
- ^ Mirach, MSN Encarta. Accessed on line August 19, 2008. Archived 2009-10-31.
- ^ a b c George A.Davis Jr. (1971) Selected List of Star Names, p. 5.
- ^ ibid. p. 19.
- ^ Kunitsch, P., Smart, T., (2006) A Dictionary of Modern Star names: A Shoert Guide to 254 Star Names and Their Derivations, Cambridge, Sky Publishing Corp., p. 50.
- ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日
- ^ 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.
- ^ Rogers, J. H. (February 1998). "Origins of the ancient constellations: I. The Mesopotamian traditions". Journal of the British Astronomical Association, no.1 108: 9–28. Bibcode:1998JBAA..108....9R.
Further reading [edit]
- 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 [edit]
- Image MIRACH
- Beta Andromedae on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
Coordinates: 
01h 09m 43.9236s, +35° 37′ 14.008″
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