{{Short description|Triple star system in the constellation Centaurus}} {{DISPLAYTITLE:Xi<sup>2</sup> Centauri}} {{other stars by Bayer designation|Xi Centauri}} {{Starbox begin | name = ξ<sup>2</sup> Centauri }} {{Starbox image | image = {{Location mark | image=Centaurus constellation map.svg | float=center | width=280 | position=right | mark=Red circle.svg | mark_width=10 | mark_link=ξ2 Cen | x=602| y=614 }} | caption = Location of ξ<sup>2</sup> Centauri (circled) }}{{Starbox observe | epoch = [[J2000.0]] | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) | constell = [[Centaurus]]<ref name=Anderson2012/> | ra = {{RA|13|06|54.639}}<ref name=GaiaDR3/> | dec = {{DEC|−49|54|22.49}}<ref name=GaiaDR3/> | appmag_v = 4.30<ref name=apjs15_459/> + 9.38<ref name=Gahm1983/> }} {{Starbox character | class = B1.5 V<ref name=Tetzlaff2011/> or B2 IV<ref name=Hohle2010/> + F7 V<ref name=Gahm1983/> | b-v = −0.197<ref name=apjs15_459/> | u-b = −0.810<ref name=apjs15_459/> | r-i = | variable = }} {{Starbox astrometry | radial_v = {{Val|+14.3|4.1}}<ref name=Bobylev2013/> | prop_mo_ra = −27.118 | prop_mo_dec = −12.808 | pm_footnote = <ref name=GaiaDR3/> | parallax = 6.7962 | p_error = 0.1797 | parallax_footnote = <ref name=GaiaDR3/> | absmag_v = −1.51<ref name=Anderson2012/> }} {{Starbox orbit | reference = <ref name=Pourbaix2004/> | period_unitless = 7.6497 d | eccentricity = 0.35 | periastron = 2418077.493 JD | periarg = 308.6 | k1 = 38.8 }} {{Starbox detail | source = | component1 = ξ<sup>2</sup> Cen A | mass = {{Val|8.1|0.1}}<ref name=Tetzlaff2011/> | radius = | luminosity_bolometric = 1,702<ref name=Gerbaldi2001/> | temperature = {{Val|20790|335|fmt=commas}}<ref name=Gerbaldi2001/> | gravity = {{Val|4.11|0.03}}<ref name=Gerbaldi2001/> | metal_fe = | rotational_velocity = 25<ref name=Wolff2007/> | age_myr = {{Val|11.5|3.7}}<ref name=Tetzlaff2011/> | component2 = ξ<sup>2</sup> Cen B | temperature2 = 6,194<ref name=Gerbaldi2001/> | luminosity2 = 2.4<ref name=Gerbaldi2001/> | mass2 = 1.25<ref name=Gerbaldi2001/> }} {{Starbox catalog | names = {{odlist | B=ξ<sup>2</sup> Cen | CD=−49°7644 | FK5=489 | HD=113791 | HIP=64004 | HR=4942 | SAO=223909 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = ksi02+Cen }} {{Starbox end}} '''Xi<sup>2</sup> Centauri''' is a [[triple star]]<ref name=Eggleton2008/> system in the southern [[constellation]] of [[Centaurus]]. Its name is a [[Bayer designation]] that is [[Romanization of Greek|Latinized]] from ξ<sup>2</sup> Centauri, and abbreviated Xi<sup>2</sup> Cen or ξ<sup>2</sup> Cen. This system is visible to the [[naked eye]] as a point of light with a combined [[apparent visual magnitude]] of 4.30,<ref name=apjs15_459/> and forms a wide [[optical double]] with the slightly dimmer [[Xi1 Centauri|ξ<sup>1</sup> Centauri]].<ref name=FogCity2003/> Based upon an annual [[stellar parallax|parallax shift]] of {{Val|6.80|ul=mas}}, Xi<sup>2</sup> Centauri lies roughly 480 [[light year]]s from the [[Sun]]. At that distance, the visual magnitude is diminished by an interstellar [[extinction (astronomy)|extinction factor]] of 0.32 due to intervening dust.<ref name=Gontcharov2012/>
This system was discovered to be a single-lined [[spectroscopic binary]] in 1910 by American astronomer [[Joseph Haines Moore]].<ref name=Moore1910/><ref name=Meubauer1931/> The pair, component A, orbit each other with a [[orbital period|period]] of 7.6497 days and an [[orbital eccentricity|eccentricity]] of 0.35.<ref name=Pourbaix2004/> The primary is a [[B-type star]] with a [[stellar classification]] of B1.5 V<ref name=Tetzlaff2011/> or B2 IV,<ref name=Hohle2010/> depending on the source. This indicates it may be a [[main sequence star]] or a more [[stellar evolution|evolved]] [[subgiant star]]. It has about 8.1 times the [[solar mass|mass of the Sun]]<ref name=Tetzlaff2011/> and radiates 1,702 times the [[solar luminosity]] from its [[stellar atmosphere|outer atmosphere]] at an [[effective temperature]] of 20,790 K.<ref name=Gerbaldi2001/> It is a [[hybrid pulsator]] and shows variations in both g and p modes.<ref name=Sharma/>
A third star, component B, is a magnitude 9.38 [[F-type main sequence star]] with a classification of F7 V. It has 1.25<ref name=Gerbaldi2001/> times the mass of the Sun and radiates 2.4<ref name=Gerbaldi2001/> times the solar luminosity at an effective temperature of 6,194<ref name=Gerbaldi2001/> K. It lies at an [[angular separation]] of 25.1 [[arc second]]s from the inner pair.<ref name=Gahm1983/> They share a [[common proper motion]], indicating they may be gravitationally bound with an orbital period of around 41,000 years.<ref name=Tokovinin2008/>
The system has a [[peculiar velocity]] of {{Val|16.2|4.2|u=km/s}}.<ref name=Bobylev2013/> It belongs to the [[Scorpius–Centaurus association]] and appears to be a member of the [[Gould's Belt]].<ref name=Bobylev2007/>
==References== <references>
<ref name=GaiaDR3>{{Cite Gaia DR3 | 6081542475600377472 | mode=cs2 | postscript=. | access-date=2025-12-19 }}</ref>
<ref name=Sharma>{{citation |postscript=. | display-authors=1 | title=Pulsating B stars in the Scorpius–Centaurus Association with TESS | last1=Sharma | first1=Awshesh N. | last2=Bedding | first2=Timothy R. | last3=Saio | first3=Hideyuki | last4=White | first4=Timothy R. | journal=Monthly Notices of the Royal Astronomical Society | volume=515 | issue=1 | pages=828–840 | year=2022 | doi=10.1093/mnras/stac1816 | doi-access=free | arxiv=2203.02582 | bibcode=2022MNRAS.515..828S }}</ref>
<ref name=Anderson2012>{{cite XHIP | 64004 | mode=cs2 | postscript=. }}</ref>
<ref name=Tokovinin2008>{{citation | title=Comparative statistics and origin of triple and quadruple stars | last1=Tokovinin | first1=A. | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=925–938 | date=September 2008 | doi=10.1111/j.1365-2966.2008.13613.x | doi-access=free | bibcode=2008MNRAS.389..925T | postscript=. |arxiv = 0806.3263 | s2cid=16452670 }}</ref>
<ref name=FogCity2003>{{citation | title=Backyard Astronomy | series=The Guides | publisher=Fog City Press | year=2003 | isbn=1877019321 | page=248 | url=https://books.google.com/books?id=QWynWiw_4i8C | postscript=. }}</ref>
<ref name=Gahm1983>{{citation | title=A study of visual double stars with early type primaries. I - Spectroscopic results | display-authors=1 | last1=Gahm | first1=G. F. | last2=Ahlin | first2=P. | last3=Lindroos | first3=K. P. | journal=Astronomy and Astrophysics Supplement Series | volume=51 | pages=143–159 | date=January 1983 | bibcode=1983A&AS...51..143G | postscript=. }}</ref>
<ref name=Meubauer1931>{{citation | title=The orbit of the spectroscopic binary ξ<sup>2</sup> Centauri | last1=Neubauer | first1=F. J. | journal=Lick Observatory Bulletin | volume=15 | pages=107–108 | year=1931 | doi=10.5479/ADS/bib/1931LicOB.15.107N | doi-access=free | bibcode=1931LicOB..15..107N | postscript=. }}</ref>
<ref name=Moore1910>{{citation | title=Ten stars having variable radial velocities | last1=Moore | first1=Joseph Haines | journal=Lick Observatory Bulletin | issue=182 | pages=55–59 | volume=6 | year=1910 | doi=10.5479/ADS/bib/1910LicOB.6.55M | bibcode=1910LicOB...6...55M | postscript=.}}</ref>
<ref name=Gerbaldi2001>{{citation | display-authors=1 | last1=Gerbaldi | first1=M. | last2=Faraggiana | first2=R. | last3=Balin | first3=N. | title=Binary systems with post-T Tauri secondaries | volume=379 | journal=Astronomy and Astrophysics | pages=162–184 |date=November 2001 | postscript=. | doi=10.1051/0004-6361:20011298 | doi-access=free | bibcode=2001A&A...379..162G }}</ref>
<ref name=Wolff2007>{{citation | last1=Wolff | first1=S. C. | last2=Strom | first2=S. E. | last3=Dror | first3=D. | last4=Venn | first4=K. | title=Rotational Velocities for B0-B3 Stars in Seven Young Clusters: Further Study of the Relationship between Rotation Speed and Density in Star-Forming Regions | journal=[[The Astronomical Journal]] | display-authors=1 | volume=133 | pages=1092–1103 | date=2007 | issue=3 | doi=10.1086/511002 | bibcode=2007AJ....133.1092W | arxiv=astro-ph/0702133 | s2cid=119074863 | postscript=. }}</ref>
<ref name=Bobylev2007>{{citation | title=Kinematics of the Scorpius–Centaurus OB association | last1=Bobylev | first1=V. V. | last2=Bajkova | first2=A. T. | journal=Astronomy Letters | volume=33 | issue=9 | pages=571–583 | date=September 2007 | doi=10.1134/S1063773707090010 | bibcode=2007AstL...33..571B | postscript=. |arxiv = 0708.0943 | s2cid=15785349 }}</ref>
<ref name=Bobylev2013>{{citation | title=Galactic kinematics from a sample of young massive stars | last1=Bobylev | first1=V. V. | last2=Bajkova | first2=A. T. | journal=Astronomy Letters | postscript=. | volume=39 | issue=8 | pages=532–549 | date=August 2013 | doi=10.1134/S106377371308001X | bibcode=2013AstL...39..532B | arxiv = 1307.1677 | s2cid=118568203 }}</ref>
<ref name=Gontcharov2012>{{citation | title=Spatial distribution and kinematics of OB stars | last1=Gontcharov | first1=G. A. | journal=Astronomy Letters | volume=38 | issue=11 | pages=694–706 | date=November 2012 | doi=10.1134/S1063773712110035 | bibcode=2012AstL...38..694G | arxiv=1606.09028 | s2cid=119108982 | postscript=. }}</ref>
<ref name=Tetzlaff2011>{{citation | 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 | postscript=. }}</ref>
<ref name=Hohle2010>{{citation | 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 | postscript=. }}</ref>
<ref name=Pourbaix2004>{{citation | title=S<sub>B<sup>9</sup></sub>: The ninth catalogue of spectroscopic binary orbits | journal=Astronomy & Astrophysics | display-authors=1 | last1=Pourbaix | first1=D. | last2=Tokovinin | first2=A. A. | last3=Batten | first3=A. H. | last4=Fekel | first4=F. C. | last5=Hartkopf | first5=W. I. | last6=Levato | first6=H. | last7=Morrell | first7=N. I. | last8=Torres | first8=G. | last9=Udry | first9=S. | volume=424 | issue=2 | pages=727–732 | date=2004 | doi=10.1051/0004-6361:20041213 | bibcode=2004A&A...424..727P | arxiv=astro-ph/0406573 | s2cid=119387088 | postscript=. }}</ref>
<ref name=Eggleton2008>{{citation | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | title=A catalogue of multiplicity among bright stellar systems | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=389 | issue=2 | pages=869–879 | date=September 2008 | doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | bibcode=2008MNRAS.389..869E | arxiv=0806.2878 | s2cid=14878976 | postscript=. }}</ref>
<ref name=apjs15_459>{{citation | last1=Gutierrez-Moreno | first1=Adelina | last2=Moreno | first2=Hugo | title=A photometric investigation of the Scorpio-Centaurus association | journal=Astrophysical Journal Supplement | volume=15 | page=459 | date=June 1968 | postscript=. | bibcode=1968ApJS...15..459G | doi=10.1086/190168 | doi-access=free }}</ref>
<ref name=SIMBAD>{{cite simbad | title=ksi02 Cen | mode=cs2 | postscript=. | access-date=2017-01-09 }}</ref>
</references>
==External links== *http://server3.wikisky.org/starview?object_type=1&object_id=884
{{Stars of Centaurus|state=collapsed}}
{{DEFAULTSORT:Xi2 Centauri}} <!-- Physical properties --> [[Category:B-type main-sequence stars]] [[Category:F-type main-sequence stars]] [[Category:Spectroscopic binaries]] [[Category:Triple star systems]] [[Category:Scorpius–Centaurus association]] <!-- Constellation & catalogues --> [[Category:Centaurus]] [[Category:Bayer objects|Centauri, Xi2]] [[Category:Bright Star Catalogue objects|4942]] [[Category:Durchmusterung objects]] [[Category:Henry Draper Catalogue objects|113791]] [[Category:Hipparcos objects|064004]]