{{Short description|Star in the constellation Centaurus}} {{about-distinguish|ε Centauri|E Centauri|HD 111915{{!}}e Centauri}} {{Starbox begin | name = ε Centauri }} {{Starbox image | image= {{Location mark |image=Centaurus constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=12|mark_link=Epsilon Centauri|x=486|y=689 }} |caption=Location of ε Centauri (circled) }} {{Starbox observe | constell = [[Centaurus]]<ref name=xhip/> | epoch = J2000 | ra = {{RA|13|39|53.25774}}<ref name=aaa474_2_653/> | dec = {{DEC|−53|27|59.0081}}<ref name=aaa474_2_653/> | appmag_v = 2.29 - 2.31<ref name=gcvs/> }} {{Starbox character | class = B1 III<ref name=an331_4_349/> | b-v = −0.22<ref name=ducati/> | u-b = −0.92<ref name=ducati/> | variable = [[Beta Cephei variable|β Cep]]<ref name=gcvs/> }} {{Starbox astrometry | radial_v = +3.0<ref name=rgcrv/> | prop_mo_ra = −15.30<ref name=aaa474_2_653/> | prop_mo_dec = −11.72<ref name=aaa474_2_653/> | parallax = 7.63 | p_error = 0.48 | parallax_footnote = <ref name=aaa474_2_653/> | absmag_v = −3.29<ref name=xhip/> }} {{Starbox detail | mass = 8.2<ref name=quintana2025/> | radius = 5.8<ref name=mcdonald2017/> | luminosity = 16,137<ref name=mcdonald2017/> | temperature = 24,937<ref name=mcdonald2017/> | gravity = 3.88<ref name=mcdonald2017/> | metal_fe = {{val|−0.14|0.10}}<ref name=aaa433_3_1031/> | rotational_velocity = 140<ref name=vanbelle2012/> | age_myr = 16.3<ref name=gratton2023/> }} {{Starbox catalog | names = {{odlist | B=ε Cen | CP=−52°6655 | FK5=504 | HD=118716 | HIP=66657 | HR=5132 | SAO=241047 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad=HD+118716 }} {{Starbox end}} '''Epsilon Centauri''' is a [[star]] in the southern [[constellation]] of [[Centaurus]]. Its name is a [[Bayer designation]] that is [[Romanization of Greek|Latinized]] from ε Centauri, and abbreviated Epsilon Cen or ε Cen. This is one of the [[List of stars in Centaurus|brightest stars]] in the constellation with a slightly variable [[apparent visual magnitude]] of +2.30. [[Parallax]] measurements put it at a distance of around {{Convert|430|ly|pc|abbr=off|lk=on}} from [[Earth]].
In [[Chinese astronomy|Chinese]], {{lang|zh|南門}} ({{lang|zh-Latn|Nán Mén}}), meaning ''[[Horn (Chinese constellation)|Southern Gate]]'', refers to an asterism consisting of ε Centauri and [[Alpha Centauri|α Centauri]].<ref name=zh/> Consequently, the [[Chinese star names|Chinese name]] for ε Centauri itself is {{lang|zh|南門一}} ({{lang|zh-Latn|Nán Mén yī}}, {{langx|en|the First Star of Southern Gate}}.)<ref name=AEEA/>
[[File:EpsilonCenLightCurve.png|thumb|left|A yellow-light [[light curve]] for Epsilon Centauri, adapted from Shobbrook (1972)<ref name="Shobbrook"/>]] ε Centauri is a massive star with 8.2 times the [[mass of the Sun]].<ref name=quintana2025/> The [[stellar spectrum|spectrum]] matches a [[stellar classification]] of B1 III,<ref name=an331_4_349/> indicating this is an [[stellar evolution|evolved]] [[giant star]]. It is radiating more than 16,000 times the [[luminosity of the Sun]]<ref name=mcdonald2017/> from its outer atmosphere at an [[effective temperature]] of about {{val|fmt=commas|25,000|ul=K}},<ref name=mcdonald2017/> giving it the blue-white hue of a B-type star.<ref name=csiro/> It is classified as a [[Beta Cephei variable|Beta Cephei type]] [[variable star]] with a primary period of 0.16961 days (4 hours 4 minutes), completing 5.9 cycles per day.<ref name=aaa433_3_1031/> During each cycle, the brightness of the star varies from apparent magnitude +2.29 to +2.31.
This star is a [[proper motion]] member of the Lower Centaurus–Crux sub-group in the [[Scorpius–Centaurus association|Scorpius–Centaurus]] [[Stellar association|OB association]], the nearest such association of co-moving massive stars to the Sun.<ref name=aaa216_1_44/> Epsilon Centauri is a relatively young star, with an age of around 16 million years.<ref name=mnras410_1_190/>
The [[IAU]] has not assigned a proper name to this star.<ref name=iau/>
==References== {{Reflist|refs=
<ref name=SIMBAD>{{cite simbad | title=Eps Cen | access-date=2025-12-08 }}</ref>
<ref name=xhip>{{cite XHIP|66657}}</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=AEEA>{{in lang|zh}} [http://aeea.nmns.edu.tw/2006/0607/ap060725.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 25 日] {{Webarchive|url=https://web.archive.org/web/20110522124501/http://aeea.nmns.edu.tw/2006/0607/ap060725.html |date=2011-05-22 }}</ref>
<ref name=iau>{{cite web |url=https://www.iau.org/public/themes/naming_stars/ |title=Naming Stars |publisher=[[International Astronomical Union]] |access-date=2023-09-14 |archive-date=2025-03-10 |archive-url=https://web.archive.org/web/20250310063743/https://www.iau.org/public/themes/naming_stars/ |url-status=dead }}</ref>
<ref name="Shobbrook">{{cite journal |last1=Shobbrook |first1=R. R. |title=Two new Beta Canis Majoris variables: epsilon Cen and delta Lup |journal=Monthly Notices of the Royal Astronomical Society |date=1972 |volume=157|bibcode=1972MNRAS.157P...5S |doi=10.1093/mnras/157.1.5P |doi-access=free }}</ref>
<ref name=aaa474_2_653>{{cite journal | last1=van Leeuwen | first1=F. | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 |date=November 2007 | pages=653–664 | doi=10.1051/0004-6361:20078357 | bibcode=2007A&A...474..653V | arxiv=0708.1752 | s2cid=18759600 }}</ref>
<ref name=rgcrv>{{cite book | last=Evans | first=D. S. | date=June 20–24, 1966 | editor1-last=Batten | editor1-first=Alan Henry | editor2-last=Heard | editor2-first=John Frederick | contribution=The Revision of the General Catalogue of Radial Velocities | volume=30 | page=57 | title=Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30 | location=University of Toronto | publisher=[[International Astronomical Union]] | bibcode=1967IAUS...30...57E }}</ref>
<ref name=ducati>{{cite journal|bibcode=2002yCat.2237....0D|title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system|journal=CDS/ADC Collection of Electronic Catalogues|volume=2237|pages=0|last1=Ducati|first1=J. R.|year=2002}}</ref>
<ref name=gcvs>{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|pages=02025|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009|display-authors=etal}}</ref>
<ref name=an331_4_349>{{cite journal | display-authors=1 | last1=Hohle | first1=M. M. | last2=Neuhäuser | first2=R. | last3=Schutz | first3=B. F. | title=Masses and luminosities of O- and B-type stars and red supergiants | journal=Astronomische Nachrichten | volume=331 | issue=4 | page=349 |date=April 2010 | doi=10.1002/asna.200911355 | bibcode=2010AN....331..349H |arxiv = 1003.2335 | s2cid=111387483 }}</ref>
<ref name=aaa216_1_44>{{cite journal | display-authors=1 | last1=de Geus | first1=E. J. | last2=de Zeeuw | first2=P. T. | last3=Lub | first3=J. | title=Physical parameters of stars in the Scorpio-Centaurus OB association | journal=Astronomy and Astrophysics | volume=216 | issue=1–2 | pages=44–61 |date=June 1989 | bibcode=1989A&A...216...44D }}</ref>
<ref name=mnras410_1_190>{{cite journal | display-authors=1 | last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M. | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun | journal=Monthly Notices of the Royal Astronomical Society | volume=410 | issue=1 | pages=190–200 |date=January 2011 | doi=10.1111/j.1365-2966.2010.17434.x | doi-access=free | bibcode=2011MNRAS.410..190T |arxiv = 1007.4883 | s2cid=118629873 }}</ref>
<ref name=aaa433_3_1031>{{cite journal | last1=Daszyńska-Daszkiewicz | first1=J. | last2=Niemczura | first2=E. | title=Metallicity of mono- and multiperiodic β Cephei stars | journal=Astronomy and Astrophysics | volume=433 | issue=3 | pages=1031–1035 |date=April 2005 | doi=10.1051/0004-6361:20040397 | bibcode=2005A&A...433.1031D |arxiv = astro-ph/0410442 | s2cid=119340011 }}</ref>
<ref name=csiro>{{cite web |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 |url-status=dead |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=gratton2023>{{cite journal |last1=Gratton |first1=R. |last2=Squicciarini |first2=V. |last3=Nascimbeni |first3=V. |last4=Janson |first4=M. |last5=Reffert |first5=S. |last6=Meyer |first6=M. |last7=Delorme |first7=P. |last8=Mamajek |first8=E. E. |last9=Bonavita |first9=M. |last10=Desidera |first10=S. |last11=Mesa |first11=D. |last12=Rigliaco |first12=E. |last13=d'Orazi |first13=V. |last14=Vigan |first14=A. |last15=Lazzoni |first15=C. |last16=Chauvin |first16=G. |last17=Langlois |first17=M. |title=Multiples among B stars in the Scorpius-Centaurus association |journal=Astronomy and Astrophysics |date=2023 |volume=678 |pages=A93 |doi=10.1051/0004-6361/202346806 |arxiv=2308.09962 |bibcode=2023A&A...678A..93G }}</ref>
<ref name=mcdonald2017>{{cite journal |last1=McDonald |first1=I. |last2=Zijlstra |first2=A. A. |last3=Watson |first3=R. A. |title=Fundamental parameters and infrared excesses of Tycho-Gaia stars |journal=Monthly Notices of the Royal Astronomical Society |date=2017 |volume=471 |issue=1 |page=770 |doi=10.1093/mnras/stx1433 |doi-access=free |arxiv=1706.02208 |bibcode=2017MNRAS.471..770M }}</ref>
<ref name=quintana2025>{{cite journal |last1=Quintana |first1=Alexis L. |last2=Wright |first2=Nicholas J. |last3=Martínez García |first3=Juan |title=A census of OB stars within 1 KPC and the star formation and core collapse supernova rates of the Milky Way |journal=Monthly Notices of the Royal Astronomical Society |date=2025 |volume=538 |issue=3 |page=1367 |doi=10.1093/mnras/staf083 |doi-access=free |arxiv=2503.08286 |bibcode=2025MNRAS.538.1367Q }}</ref>
<ref name=vanbelle2012>{{cite journal |last1=Van Belle |first1=Gerard T. |title=Interferometric observations of rapidly rotating stars |journal=Astronomy and Astrophysics Review |date=2012 |volume=20 |issue=1 |article-number=51 |doi=10.1007/s00159-012-0051-2 |arxiv=1204.2572 |bibcode=2012A&ARv..20...51V }}</ref>
}}
{{Stars of Centaurus}}
<!-- Physical properties --> [[Category:Beta Cephei variables]] [[Category:B-type giants]] [[Category:Lower Centaurus Crux]] <!-- Constellation & catalogues --> [[Category:Centaurus]] [[Category:Bayer objects|Centauri, Epsilon]] [[Category:Bright Star Catalogue objects|5132]] [[Category:Durchmusterung objects|CD-52 06655]] [[Category:Henry Draper Catalogue objects|118716]] [[Category:Hipparcos objects|066657]] [[Category:Stars with proper names|Nán Mén yī]] [[Category:Brightest stars]]