{{Short description|Red giant star in the constellation Pegasus}} {{redirect|Scheat|the star in Aquarius|Delta Aquarii}} {{Starbox begin}} {{Starbox image | image= {{Location mark |image=Pegasus constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=12|mark_link=Beta Pegasi|x=409|y=294 }} |caption=Location of β Pegasi (circled) }} {{Starbox observe | epoch = J2000 | ra = {{RA|23|03|46.45746}}<ref name=aaa474_2_653/> | dec = {{DEC|+28|04|58.0336}}<ref name=aaa474_2_653/> | appmag_v = 2.31{{snd}}2.74<ref name=var/> | constell = Pegasus }} {{Starbox character | type = AGB<ref name=guerrero2020/> | class = M2.5II–IIIe<ref name=SIMBAD /> | b-v = +1.67<ref name=clpl4_99/> | u-b = +1.96<ref name=clpl4_99/> | variable = Semi-regular<ref name=mnras400_4_1945/> }} {{Starbox astrometry | radial_v = +8.7<ref name=gcsrv/> | prop_mo_ra = +187.65<ref name=aaa474_2_653/> | prop_mo_dec = +136.93<ref name=aaa474_2_653/> | parallax = 16.64 | p_error = 0.15 | parallax_footnote = <ref name=aaa474_2_653/> | dist_footnote = <ref name=aaa474_2_653/><!-- Distance automatically calculated from parallax by {{starbox astrometry}} --> | absmag_v = −1.41<ref name=huang2012/> }} {{Starbox detail | mass = {{val|1.7|0.3}}<ref name="halabi"/> | radius = {{val|109|7}}<ref name=ArroyoTorres2014/> | luminosity = 1,644<ref name="halabi"/>{{Efn|1=Calculated from bolometric magnitude in the equation 10{{sup|0.4(4.74-M{{sub|bol}})}}, where "M{{sub|bol}}" is the bolometric magnitude.}} | temperature = 3,606<ref name="halabi"/> | gravity = 1.20<ref name=aaa480_1_91/> | metal_fe = −0.11<ref name=aaa480_1_91/> | rotational_velocity = 9.7<ref name=aj135_1_209/> | age = }} {{Starbox catalog | names = Scheat, 53 Pegasi, HR 8775, BD+27°4480, HD 217906, SAO 90981, FK5 870, HIP 113881<ref name=SIMBAD/> }} {{Starbox reference | Simbad=HD+217906 }} {{Starbox end}}
'''Beta Pegasi''' ('''β Pegasi''', abbreviated '''Beta Peg''', '''β Peg'''), formally named '''Scheat''' {{IPAc-en|'|sh|iː|æ|t}},<ref name=Kunitzsch/><ref name="IAU-CSN"/> is a red giant star and the second-brightest star (after Epsilon Pegasi) in the constellation of Pegasus. It forms the upper right corner of the Great Square of Pegasus,<ref name=allen1899/> a prominent rectangular asterism.
==Nomenclature==
''β Pegasi'' (Latinised to ''Beta Pegasi'') is the star's Bayer designation.
It bore the traditional name of ''Scheat'', a name that had also been used for Delta Aquarii. The name was derived from the Arabic ''Al Sā'id'' "the upper arm", or from ''Sa'd''.<ref name=allen1899/> In 2016, the International Astronomical Union organised a Working Group on Star Names (WGSN)<ref name="WGSN"/> to catalog and standardise proper names for stars. The WGSN's first bulletin of July 2016<ref name="WGSN1"/> included a table of the first two batches of names approved by the WGSN; which included ''Scheat'' for this star (the name ''Skat'' was later approved for Delta Aquarii<ref name="IAU-CSN"/>).
In Chinese, {{lang|zh|室宿}} ({{lang|zh-Latn|Shì Xiù}}), meaning ''Encampment'', refers to an asterism consisting β Pegasi and α Pegasi.<ref name=zh/> Consequently, the Chinese name for β Pegasi itself is {{lang|zh|室宿二}} ({{lang|zh-Latn|Shì Xiù èr}}), "the Second Star of Encampment".<ref name=lcsd/>
==Distance and properties== [[File:BetaPegLightCurve.png|thumb|left|A light curve for Beta Pegasi, plotted from ''Hipparcos'' data<ref name=HIPCurve/>]] Based upon parallax measurements, Beta Pegasi is located about {{Convert|196|ly|pc|abbr=off|lk=on}} from the Sun.<ref name=aaa474_2_653/> It is unusual among bright stars in having a relatively cool surface temperature compared to stars like the Sun. This star has a stellar classification of M2.3 II–III,<ref name=SIMBAD /> which indicates the spectrum has characteristics partway between a bright giant and a giant star. It has expanded until it is 109 times as large,<ref name=ArroyoTorres2014/> and has a total luminosity of 1,640 times that of the Sun.<ref name="halabi"/> The effective temperature of the star's outer envelope is about 3,600 K,<ref name="halabi"/> giving the star the characteristic orange-red hue of an M-type star.<ref name=csiro/> The photosphere is sufficiently cool for molecules of titanium oxide to form.<ref name=jbaa106_1_11/>
Johann Friedrich Julius Schmidt discovered that Beta Pegasi is a variable star, in 1847.<ref name="Cannon1907"/> Beta Pegasi is a semi-regular variable with a period of 43.3 days<ref name=mnras400_4_1945/> and a brightness that varies from magnitude +2.31 to +2.74.<ref name=var/> It is losing mass at a rate at or below 10<sup>−8</sup> times the Sun's mass per year, which is creating an expanding shell of gas and dust with a radius of about 3,500 times the Sun's radius (16 astronomical units).<ref name=aaa265_2_711/> {{clear left}}
==Notes== {{Notelist}}
==References== {{reflist|30em|refs=
<ref name="Cannon1907">{{cite journal |last1=Cannon |first1=Annie J. |title=Second catalogue of variable stars |journal=Annals of Harvard College Observatory |date=1907 |volume=55 |pages=1–94 |bibcode=1907AnHar..55....1C }}</ref>
<ref name=lcsd>{{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|url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |date=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>
<ref name=zh>{{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}}.</ref>
<ref name="WGSN1">{{cite web | url=https://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 |access-date=28 July 2016}}</ref>
<ref name=guerrero2020>{{cite journal |bibcode=2020MNRAS.491..680G |title=The effect of pulsation on the near-ultraviolet spectrum of AGB stars |last1=Guerrero |first1=Martín A. |last2=Ortiz |first2=Roberto |journal=Monthly Notices of the Royal Astronomical Society |date=2020 |volume=491 |issue=1 |page=680 |doi=10.1093/mnras/stz2966 |doi-access=free }}</ref>
<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN) | access-date=22 May 2016 | archive-date=10 June 2016 | archive-url=https://web.archive.org/web/20160610172014/https://www.iau.org/science/scientific_bodies/working_groups/280/ | url-status=dead }}</ref>
<ref name="IAU-CSN">{{cite web | url=https://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}</ref>
<ref name=Kunitzsch>{{cite book |last1=Kunitzsch |first1=Paul |last2=Smart |first2=Tim |date = 2006 |edition = 2nd rev. |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations |publisher = Sky Pub |location = Cambridge, Massachusetts |isbn = 978-1-931559-44-7 }}</ref>
<ref name=ArroyoTorres2014>{{cite journal | title=VLTI/AMBER observations of cold giant stars: atmospheric structures and fundamental parameters | last1=Arroyo-Torres | first1=B. | last2=Martí-Vidal | first2=I. | last3=Marcaide | first3=J. M. | last4=Wittkowski | first4=M. | last5=Guirado | first5=J. C. | last6=Hauschildt | first6=P. H. | last7=Quirrenbach | first7=A. | last8=Fabregat | first8=J. | journal=Astronomy & Astrophysics | display-authors=1 | volume=566 | id=A88 | pages=11 | date=June 2014 | doi=10.1051/0004-6361/201323264 | bibcode=2014A&A...566A..88A | arxiv=1404.7384 | s2cid=16778588 }}</ref>
<ref name=HIPCurve>{{citation |postscript=. |title=Light Curve |url=https://www.cosmos.esa.int/web/hipparcos/java-tools/light-curve |website=Hipparcos ESA |publisher=ESA |access-date=21 September 2022}}</ref>
<ref name=aaa474_2_653>{{citation | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 |arxiv = 0708.1752 | s2cid=18759600 }}</ref>
<ref name=aaa480_1_91>{{citation | display-authors=1 | last1=Soubiran | first1=C. | last2=Bienaymé | first2=O. | last3=Mishenina | first3=T. V. | last4=Kovtyukh | first4=V. V. | title=Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants | journal=Astronomy and Astrophysics | date=2008 | volume=480 | issue=1 | pages=91–101 | bibcode=2008A&A...480...91S | doi=10.1051/0004-6361:20078788 |arxiv = 0712.1370 | s2cid=16602121 }}</ref>
<ref name=gcsrv>{{citation | last=Wilson | first=Ralph Elmer | date=1953 | title=General Catalogue of Stellar Radial Velocities | journal=Washington | publisher=Carnegie Institution of Washington | location=Washington | bibcode=1953GCRV..C......0W }}</ref>
<ref name=aj135_1_209>{{citation | display-authors=1 | last1=Massarotti | first1=Alessandro | last2=Latham | first2=David W. | last3=Stefanik | first3=Robert P. | last4=Fogel | first4=Jeffrey | title=Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity | journal=The Astronomical Journal | volume=135 | issue=1 | pages=209–231 |date=January 2008 | doi=10.1088/0004-6256/135/1/209 | bibcode=2008AJ....135..209M | s2cid=121883397 | doi-access=free }}</ref>
<ref name=clpl4_99>{{cite journal | display-authors=1 | last1=Johnson | first1=H. L. | last2=Iriarte | first2=B. | last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z. | title=UBVRIJKL photometry of the bright stars | journal=Communications of the Lunar and Planetary Laboratory | volume=4 | issue=99 | pages=99 | date=1966 | bibcode=1966CoLPL...4...99J }}</ref>
<ref name="halabi">{{Cite journal |last1=Halabi |first1=Ghina M. |last2=Eid |first2=Mounib El |date=2015-08-01 |title=Exploring masses and CNO surface abundances of red giant stars |journal=Monthly Notices of the Royal Astronomical Society |volume=451 |issue=3 |pages=2957–2967 |doi=10.1093/mnras/stv1141 |doi-access=free |issn=0035-8711|arxiv=1507.01517 |bibcode=2015MNRAS.451.2957H }}</ref>
<ref name=SIMBAD>{{citation | url=https://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+217906 | title =V* bet Peg -- Pulsating variable Star | publisher=Centre de Données astronomiques de Strasbourg | work=SIMBAD | access-date=2010-01-05 }}</ref>
<ref name=mnras400_4_1945>{{citation | display-authors=1 | last1=Tabur | first1=V. | last2=Bedding | first2=T. R. | last3=Kiss | first3=L. L. | last4=Moon | first4=T. T. | last5=Szeidl | first5=B. | last6=Kjeldsen | first6=H. | title=Long-term photometry and periods for 261 nearby pulsating M giants | journal=Monthly Notices of the Royal Astronomical Society | volume=400 | issue=4 | pages=1945–1961 |date=December 2009 | doi=10.1111/j.1365-2966.2009.15588.x | doi-access=free | bibcode=2009MNRAS.400.1945T |arxiv = 0908.3228 | s2cid=15358380 }}</ref>
<ref name=var>{{citation | title=Query= bet Peg | url=http://www.sai.msu.su/gcvs/cgi-bin/search.cgi?search=bet+Peg | publisher=Centre de Données astronomiques de Strasbourg | work=General Catalogue of Variable Stars | access-date=2010-01-05}}</ref>
<ref name=allen1899>{{citation | last1=Allen | first1=Richard Hinckley | date=1899 | title=Star Names: Their Lore and Meaning | publisher=Dover Publications Inc. | location=New York, NY | isbn=0-486-21079-0 | page=325 | author-link=Richard Hinckley Allen | url=https://books.google.com/books?id=5xQuAAAAIAAJ&pg=PA325 }}</ref>
<ref name=aaa265_2_711>{{citation | last1=Mauron | first1=N. | last2=Caux | first2=E. | title=K I/Na I scattering observations in circumstellar envelopes - Alpha(1) Herculis, Omicron Ceti, TX PISCIUM and Beta Pegasi | journal=Astronomy and Astrophysics | volume=265 | issue=2 | pages=711–725 |date=November 1992 | bibcode=1992A&A...265..711M }}. Solar Radius = 0.0046491 AU.</ref>
<ref name=jbaa106_1_11>{{citation | last1=Gavin | first1=M. | title=Stellar spectroscopy with CCDs - some preliminary results | journal=Journal of the British Astronomical Association | volume=106 | issue=1 | pages=11–15 |date=February 1996 | bibcode=1996JBAA..106...11G }}</ref>
<ref name=csiro>{{citation |title=The Colour of Stars |date=December 21, 2004 |work=Australia Telescope, Outreach and Education |publisher=Commonwealth Scientific and Industrial Research Organisation |url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |access-date=2012-01-16 |archive-url=https://web.archive.org/web/20120318151427/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |archive-date=2012-03-18 }}</ref>
<ref name=huang2012>{{citation | display-authors=1 | last1=Huang | first1=W. | last2=Wallerstein | first2=G. | last3=Stone | first3=M. | title=A catalogue of Paschen-line profiles in standard stars | journal=Astronomy & Astrophysics | volume=547 | pages=A62 | year=2012 | bibcode=2012A&A...547A..62H | arxiv=1210.7893 | doi=10.1051/0004-6361/201219804 | s2cid=119286159 | postscript=. }}</ref>
}}
{{Stars of Pegasus}}
{{Sky|23|03|46.458|+|28|04|58.04|200}}
Pegasi, Beta Category:M-type bright giants Category:M-type giants Category:Pegasus (constellation) Scheat Pegasi, 53 8775 217906 113881 BD+27 4480 Category:Semiregular variable stars Category:Emission-line stars Category:Asymptotic-giant-branch stars Category:Brightest stars