View source for Astronomy:Omicron1 Centauri

{{Short description|Star in the constellation Centaurus}}
{{DISPLAYTITLE:Omicron<sup>1</sup> Centauri}}
{{Starbox begin
| name = ο<sup>1</sup> Centauri
}}
{{Starbox image
 | image=
{{Location mark
|image=Centaurus constellation map.svg
|float=center
|alt=
|label=
|position=right
|width=280
|mark=Red circle.svg
|mark_width=10
|mark_link=ο<sup>1</sup> Centauri
|x=840|y=894
}}
|caption=Location of ο<sup>1</sup> Cen (circled)
}}{{Starbox observe
| epoch = J2000.0
| constell = [[Astronomy:Centaurus|Centaurus]]
| ra = {{RA|11|31|46.07}}<ref name=dr3/>
| dec = {{DEC|−59|26|31.4}}<ref name=dr3/>
| appmag_v = +5.13<ref name=malyuto/>
}}
{{Starbox character
| class = G3 0-Ia<ref name=mk/><ref name=ferro/>
| b-v = +1.08<ref name=malyuto/>
| u-b =
| variable = [[Astronomy:Semiregular variable star|SRd]]<ref name=gcvs/>
}}
{{Starbox astrometry
| radial_v = −20.00<ref name=Gontcharov/>
| prop_mo_ra = −4.491<ref name=dr3/>
| prop_mo_dec = +1.604<ref name=dr3/>
| parallax = 0.3254
| p_error = 0.0734
| parallax_footnote = <ref name=dr3/>
| absmag_v = −9.0<ref name=ferro/>
}}
{{Starbox detail
| mass=17<ref name="kaler"/>
| radius=270<ref name="kaler"/>
| luminosity=68,000<ref name="kaler"/>
| temperature=4,873<ref name=McDonald/>
| metal_fe=
| gravity=0.19<ref name=Mallik/>
| rotational_velocity=
| age_myr=10–12<ref name="kaler"/>
}}
{{Starbox catalog
| names = HR&nbsp;4441, HD&nbsp;100261, CD−58°4100, HIP&nbsp;56243, SAO&nbsp;239145, [[Astronomy:Boss General Catalogue|GC]]&nbsp;15818, CCDM&nbsp;J11318-5927, AAVSO&nbsp;1127-58
}}
{{Starbox reference
| Simbad = HD+100261
}}
{{Starbox end}}

'''Omicron<sup>1</sup> Centauri''' (ο<sup>1</sup> Cen, ο<sup>1</sup> Centauri) is a [[Astronomy:Star|star]] in the [[Astronomy:Constellation|constellation]] [[Astronomy:Centaurus|Centaurus]].  It is approximately 10,000 [[Light year|light year]]s from [[Astronomy:Earth|Earth]].

[[File:Omicron1CenLightCurve.png|thumb|left|A [[Astronomy:Light curve|light curve]] for Omicron<sup>1</sup> Centauri, adapted from O'Connell (1961)<ref name="O'Connell"/>]]
ο<sup>1</sup> Centauri is a yellow [[Astronomy:Stellar classification|G-type]] [[Astronomy:Supergiant|supergiant]] or [[Astronomy:Hypergiant|hypergiant]] with a mean [[Astronomy:Apparent magnitude|apparent magnitude]] of +5.13.  It is classified as a [[Astronomy:Semiregular variable star|semiregular]] [[Astronomy:Variable star|variable star]] and its brightness varies from magnitude +5.8 to +6.6 with a period of 200 days.<ref name=gcvs/>  Other studies have reported only small brightness variations.<ref name=IBVS/><ref name=sterken/>  It is the MK spectral standard for class G3 O-Ia,<ref name=garcia1989/> indicating a highly luminous mass-losing [[Astronomy:Hypergiant|hypergiant]] star.  It has also be classified as F8 Ia0<ref name=Mantegazza/> and F7 Ia/ab.<ref name=Sowell/>  The size, luminosity, and distance are equally uncertain.

ο<sup>1</sup> Cen forms a very close naked eye double star with [[Astronomy:Omicron2 Centauri|ο<sup>2</sup> Centauri]], a hotter supergiant that may be physically associated.  ο<sup>1</sup> Cen also has an 11th magnitude companion only 13.5" distant,<ref name=wds/> Although it appears to be a foreground star unrelated to the other two.<ref name=dr3b/>
{{clear left}}

== References ==
{{Reflist|colwidth=30em|refs=

<ref name=dr3>{{cite Gaia DR3|5336490478704008960}}</ref>

<ref name=dr3b>{{cite Gaia DR3|5336490478704007936}}</ref>

<ref name=wds>{{cite journal|bibcode=2001AJ....122.3466M|title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog|journal=The Astronomical Journal|volume=122|issue=6|pages=3466|last1=Mason|first1=Brian D.|last2=Wycoff|first2=Gary L.|last3=Hartkopf|first3=William I.|last4=Douglass|first4=Geoffrey G.|last5=Worley|first5=Charles E.|year=2001|doi=10.1086/323920|doi-access=free}}</ref>

<ref name=Sowell>{{cite journal|bibcode=1990AJ....100..834S|title=A survey of Balmer-line profiles and IRAS fluxes in forty yellow supergiants|journal=Astronomical Journal|volume=100|pages=834|last1=Sowell|first1=James R.|year=1990|doi=10.1086/115567}}</ref>

<ref name=Mantegazza>{{cite journal|bibcode=1992A&A...265..527M|title=Luminosities of yellow supergiants from near-infrared spectra - Calibration through Magellanic Cloud stars|journal=Astronomy and Astrophysics|volume=265|pages=527|last1=Mantegazza|first1=L.|year=1992}}</ref>

<ref name=garcia1989>{{cite journal
 | last1=Garcia | first1=B.
 | title=A list of MK standard stars
 | journal=Bulletin d'Information du Centre de Données Stellaires
 | volume=36 | pages=27 | year=1989
 | bibcode=1989BICDS..36...27G }}</ref>

<ref name=sterken>{{cite journal|bibcode= 1993A&AS..102...79S|title= Longterm Photometry of Variables at ESO - Part Two - the Second Data Catalogue 1986-1990|journal= Astronomy and Astrophysics Supplement|volume= 102|pages= 79|last1= Sterken|first1= C.|last2= Manfroid|first2= J.|last3= Anton|first3= K.|last4= Barzewski|first4= A.|last5= Bibo|first5= E.|last6= Bruch|first6= A.|last7= Burger|first7= M.|last8= Duerbeck|first8= H. W.|last9= Duemmler|first9= R.|last10= Heck|first10= A.|last11= Hensberge|first11= H.|last12= Hiesgen|first12= M.|last13= Inklaar|first13= F.|last14= Jorissen|first14= A.|last15= Juettner|first15= A.|last16= Kinkel|first16= U.|last17= Liu|first17= Zongli|last18= Mekkaden|first18= M. V.|last19= Ng|first19= Y. K.|last20= Niarchos|first20= P.|last21= Puttmann|first21= M.|last22= Szeifert|first22= T.|last23= Spiller|first23= F.|last24= Van Dijk|first24= R.|last25= Vogt|first25= N.|last26= Wanders|first26= I.|year= 1993}}</ref>

<ref name=IBVS>{{cite journal|bibcode=1971IBVS..558....1F|title=New Bright Southern Variable Stars|journal=Information Bulletin on Variable Stars|volume=558|pages=1|last1=Friedrich|first1=D.|last2=Schoffel|first2=E.|year=1971}}</ref>

<ref name=Mallik>{{cite journal|bibcode=1998BASI...26..479M|title=The central depth of the Ca II triplet lines as a discriminant of chromospheric activity in late type stars|journal=Bulletin of the Astronomical Society of India|volume=26|pages=479|last1=Mallik|first1=Sushma V.|year=1998}}</ref>

<ref name=McDonald>{{cite journal|bibcode= 2012MNRAS.427..343M|title= Fundamental parameters and infrared excesses of Hipparcos stars|journal= Monthly Notices of the Royal Astronomical Society|volume= 427|pages= 343–357|last1= McDonald|first1= I.|last2= Zijlstra|first2= A. A.|last3= Boyer|first3= M. L.|year= 2012|issue= 1|doi= 10.1111/j.1365-2966.2012.21873.x|arxiv = 1208.2037 |s2cid= 118665352}}</ref>

<ref name=ferro>{{cite journal|bibcode=1991MNRAS.250....1A|title=A new discussion on the M(v) - W(O I 7774 A) relationship for F-G stars in the light of high-resolution data|journal=Monthly Notices of the Royal Astronomical Society|volume=250|pages=1|last1=Arellano Ferro|first1=A.|last2=Giridhar|first2=Sunetra|last3=Goswami|first3=Aruna|year=1991|doi=10.1093/mnras/250.1.1|doi-access=free}}</ref>

<ref name=Gontcharov>{{cite journal|bibcode=2006AstL...32..759G|title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system|journal=Astronomy Letters|volume=32|issue=11|pages=759–771|last1=Gontcharov|first1=G. A.|year=2006|doi=10.1134/S1063773706110065|arxiv = 1606.08053 |s2cid=119231169}}</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|display-authors=0|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}</ref>

<ref name=mk>{{cite journal|bibcode=1980ApJS...42..541K|title=Revised MK spectral types for G, K, and M stars|journal=Astrophysical Journal Supplement Series|volume=42|pages=541|last1=Keenan|first1=P. C.|last2=Pitts|first2=R. E.|year=1980|doi=10.1086/190662|doi-access=free}}</ref>

<ref name=malyuto>{{cite journal|bibcode=1997A&A...325..693M|title=Quantitative spectral classification based on photoelectric spectrum scanner measurements of F-K stars|journal=Astronomy and Astrophysics|volume=325|pages=693|last1=Malyuto|first1=V.|last2=Schmidt-Kaler|first2=T.|year=1997}}</ref>

<ref name="O'Connell">{{cite journal |last1=O'Connell |first1=D. J. K. |title=The semi-regular variable o<sup>1</sup> Centauri |journal=Ricerche Astronomiche |date=1961 |volume=6 |issue=13 |pages=353–359 |bibcode=1961RA......6..353O }}</ref>

<ref name="kaler">{{citation | first1=James B. | last1=Kaler | title=Omicron 1,2 Centauri | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/omicen.html | access-date=2017-12-05 }}</ref>

}}

{{Stars of Centaurus}}

{{DEFAULTSORT:Omicron1 Centauri}}
[[Category:Bayer objects|Centauri, Omicron1]]
[[Category:Semiregular variable stars]]
[[Category:G-type hypergiants]]
[[Category:Bright Star Catalogue objects|4441]]
[[Category:Hipparcos objects|056243]]
[[Category:Henry Draper Catalogue objects|100261]]
[[Category:Durchmusterung objects]]

{{Sourceattribution|Omicron1 Centauri}}