Alpha Pegasi

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α Pegasi
Template:Location mark
Location of α Pegasi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pegasus
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 2.48[2]
Characteristics
Evolutionary stage Giant star or main sequence star
Spectral type B9V,[3] B9.5III,[4] B9III[5] A0 IV[6]
U−B Template:Engvar –0.06[2]
B−V Template:Engvar –0.04[2]
Variable type suspected[7]
Astrometry
Radial velocity (Rv)–2.2[8] km/s
Proper motion (μ) RA: 60.40 ± 0.17[1] mas/yr
Dec.: -41.30 ± 0.16[1] mas/yr
Parallax (π)24.46±0.19 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)–0.718[9]
Details
Mass3.5[10] Template:Solar mass
RadiusTemplate:Val[11] Template:Solar radius
Luminosity165[12] Template:Solar luminosity
Surface gravity (log g)Template:Val[11] cgs
TemperatureTemplate:Val[11] K
Metallicity [Fe/H]−0.28[13] dex
Rotational velocity (v sin i)130[11] km/s
Age200[10] Myr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Markab, Marchab, 54 Pegasi, HR 8781, BD+14°4926, HD 218045, SAO 108378, FK5 871, HIP 113963
Database references
SIMBADdata

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Alpha Pegasi (α Pegasi, abbreviated Alpha Peg, α Peg), formally named Markab Template:IPAc-en,[14][15] is the third-brightest star in the constellation of Pegasus and one of the four stars in the asterism known as the Great Square of Pegasus.

Properties

Alpha Pegasi has a stellar classification of A0 IV, indicating that it is an A-type subgiant star that has exhausted the hydrogen at its core and has evolved beyond the main sequence. Its spectrum has also been classified as B9V[3] and B9.5III.[4]

It is rotating rapidly, with a projected rotational velocity of 130 km/s giving a lower bound on the azimuthal velocity along the star's equator. The effective temperature of the photosphere is about 10,000 K and the star has expanded to nearly five times the radius of the Sun, emitting 165 times as much energy as the sun.

Nomenclature

α Pegasi (Latinised to Alpha Pegasi) is the star's Bayer designation. It bore the traditional name Markab (or Marchab), which derived from an Arabic word مركب markab "the saddle of the horse", or is mistranscription of Mankib, which itself comes from an Arabic phrase منكب الفرس Mankib al-Faras "(the Star of) the Shoulder (of the Constellation) of the Horse" for Beta Pegasi.

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[16] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included Markab for this star.[17]

In ancient Indian astronomy, this along with β Pegasi is the main star in Purva Bhadrapada, the 25th nakshatra asterism.[18]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Encampment, refers to an asterism consisting α Pegasi and β Pegasi.[19] Consequently, the Chinese name for α Pegasi itself is Script error: No such module "Lang". (Script error: No such module "Lang".), "the First Star of Encampment".[20]

References

Template:Reflist

Template:Stars of Pegasus

  1. ↑ a b c d e Cite error: Invalid <ref> tag; no text was provided for refs named aaa474_2_653
  2. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named clpl4_99
  3. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Hoffleit1991
  4. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named osawa1959
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named simbad
  6. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named abt
  7. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named gcvs
  8. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named scfs
  9. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named katz2011
  10. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named derosa2014
  11. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named gordon2019
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named mcdonald2017
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named gaspar2016
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Kunitzsch
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named WGSN
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named WGSN1
  18. ↑ Script error: No such module "citation/CS1".
  19. ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
  20. ↑ Template:In lang 香港太空館 - 研究資源 - 亮星中英對照表 Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.
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