Beta Andromedae
<templatestyles src="Module:Hatnote/styles.css"></templatestyles>
 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] |
| 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] cgs |
| 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]
Properties
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 1995[10] times the luminosity of the Sun at an effective temperature of 3842 K.[11]
Naming and etymology
- 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) Baṭn al-Ḥūt, the Belly of the Fish, or Qalb al-Ḥūt, the Heart of the Fish.[12][17] The star has also been called Cingulum and Ventrale.[12] This al-Ḥūt was an indigenous Arabic constellation, not the Western "Northern Fish" part of the constellation Pisces.[17] These names are not from the Arabic marāqq, loins, because it was never called al-Marāqq in Arabian astronomy.[17] 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.[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
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 3.2 3.3 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.
- ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 5.0 5.1 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.
- ↑ 7.0 7.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Mirach, Stars, Jim Kaler. Accessed on line August 13, 2008.
- ↑ 10.0 10.1 10.2 10.3 10.4 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 11.0 11.1 11.2 11.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 12.0 12.1 12.2 12.3 12.4 12.5 12.6 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 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.
- ↑ 17.0 17.1 17.2 George A.Davis Jr. (1971) Selected List of Star Names, p. 5.
- ↑ ibid. p. 19.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ (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.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
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
- Image MIRACH
- Beta Andromedae on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
