Alpha Pegasi

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Star in the constellation Pegasus

title: "Alpha Pegasi" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["bayer-objects", "a-type-subgiants", "pegasus-(constellation)", "stars-with-proper-names", "flamsteed-objects", "hipparcos-objects", "bright-star-catalogue-objects", "henry-draper-catalogue-objects", "durchmusterung-objects", "suspected-variables"] description: "Star in the constellation Pegasus" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Alpha_Pegasi" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Star in the constellation Pegasus ::

| name = α Pegasi | image= |image=Pegasus constellation map.svg|alt=|float=center|width=240 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=α Pegasi |x=396|y=532 |caption=Location of α Pegasi (circled) | epoch = J2000 | constell = Pegasus | ra = | dec = | appmag_v = 2.48 | type = Giant star or main sequence star | class = B9V, B9.5III, B9III A0 IV | b-v = –0.04 | u-b = –0.06 | variable = suspected | radial_v = –2.2 | prop_mo_ra = 60.40 ± 0.17 | prop_mo_dec = -41.30 ± 0.16 | gal_lat = –40.3811 | gal_lon = 88.2798 | parallax = 24.46 | p_error = 0.19 | parallax_footnote = | absmag_v = –0.718 | mass = 3.5 | radius = | luminosity = 165 | temperature = | metal_fe = −0.28 | gravity = | rotational_velocity = 130 | age_myr = 200 | names = Markab, Marchab, 54 Pegasi, HR 8781, BD+14°4926, HD 218045, SAO 108378, FK5 871, HIP 113963 |Simbad=alf+Peg

Alpha Pegasi (α Pegasi, abbreviated Alpha Peg, α Peg), formally named Markab , 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 and B9.5III.

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) 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.

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

In Chinese, 室宿 (Shì Xiù), meaning Encampment, refers to an asterism consisting α Pegasi and β Pegasi. Consequently, the Chinese name for α Pegasi itself is 室宿一 (Shì Xiù yī), "the First Star of Encampment".

References

References

  1. "IAU Catalog of Star Names".
  2. "Indian Names (All Terms)". [[IAU Working Group on Star Names]].
  3. {{in lang. zh ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, {{ISBN. 978-986-7332-25-7.
  4. {{in lang. zh [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive. link. (2008-10-25 , Hong Kong Space Museum. Accessed on line November 23, 2010.)
  5. van Leeuwen, F.. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics.
  6. "Markab".
  7. (1999). "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions". Astronomisches Rechen-Institut Heidelberg.
  8. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory.
  9. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement.
  10. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S.
  11. (2019). "Angular Sizes, Radii, and Effective Temperatures of B-type Stars from Optical Interferometry with the CHARA Array". The Astrophysical Journal.
  12. (2011). "Probing the Galactic thick disc vertical properties and interfaces". Astronomy and Astrophysics.
  13. "IAU Working Group on Star Names (WGSN)".
  14. "Bulletin of the IAU Working Group on Star Names, No. 1".
  15. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H.

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bayer-objectsa-type-subgiantspegasus-(constellation)stars-with-proper-namesflamsteed-objectshipparcos-objectsbright-star-catalogue-objectshenry-draper-catalogue-objectsdurchmusterung-objectssuspected-variables