{{Short description|Variable binary star system in the constellation Centaurus}} {{Starbox begin | name = κ 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=10|mark_link=κ Cen |x=160|y=482 }} | caption = Location of κ Centauri (circled) }} {{Starbox observe 2s | epoch = [[J2000.0]] | constell = [[Centaurus]] | component1 = κ Cen AB | ra1 = {{RA|14|59|09.6849}}<ref name=aaa474_2_653/> | dec1 = {{DEC|−42|06|15.107}}<ref name=aaa474_2_653/> | appmag_v1 = +3.14<ref name=apjs15_459/> {{nowrap|(3.34 + 4.71)}}<ref name=Gomez2022/> | component2 = κ Cen C | ra2 = {{RA|14|59|10.0318}}<ref name=GaiaDR3-C/> | dec2 = {{DEC|−42|06|14.602}}<ref name=GaiaDR3-C/> | appmag_v2 = 11.5<ref name=Tokovinin2018/> }} {{Starbox character | component1 = κ Cen AB | type = [[main sequence]] | class = B2V + B3V<ref name=Gomez2022/> | b-v = −0.204<ref name=apjs15_459/> | u-b = −0.805<ref name=apjs15_459/> | variable = Candidate [[Beta Cephei variable|β Cep]]<ref name=asp2002_204/> | component2 = κ Cen C | type2 = [[main sequence]]<ref name=DD2017/> | class2 = K2V<ref name=DD2017/> }} {{Starbox astrometry | component1 = κ Cen AB | radial_v = +8.0<ref name=rgcrv/> | prop_mo_ra = −17.62 | prop_mo_dec = −22.51 | pm_footnote = <ref name=aaa474_2_653/> | parallax = 8.14 | p_error = 0.33 | parallax_footnote = <ref name=Gomez2022/> | absmag_v = −2.2<ref name=aaa216_1_44/> | component2 = κ Cen C | prop_mo_ra2 = −18.769 | prop_mo_dec2 = −23.688 | pm_footnote2 = <ref name=GaiaDR3-C/> | parallax2 = 7.4667 | p_error2 = 0.0994 | parallax_footnote2 = <ref name=GaiaDR3-C/> }} {{Starbox orbit | reference = <ref name=Gomez2022/> | primary = κ Cen A | name = κ Cen B | period_unitless = {{Val|58.52|1.50}} years | axis_unitless = {{Val|0.287|0.008|ul="}} | eccentricity = {{Val|0.304|0.009}} | inclination = {{Val|90.9|0.5}} | node = {{Val|156.1|0.5}} | periarg = {{Val|215.1|2.0}} | periastron = {{Val|fmt=none|2011.10|0.30}} }} {{Starbox detail | component1 = κ Cen A | mass = {{val|8.38|0.27}}<ref name=Gomez2022/> | gravity = {{val|4.02|0.20}}<ref name=an330_4_317/> | rotational_velocity = 10<ref name=coapa239_1/> | radius = {{val|4.4|0.7}}<ref name=an330_4_317/> | luminosity = 2,500<ref name=an330_4_317/> | temperature = 20,900<ref name=Gomez2022/> | metal_fe = | age_myr = {{val|18.2|3.2}}<ref name=mnras410_1_190/> | component2 = κ Cen B | mass2 = {{Val|4.41|0.36}}<ref name=Gomez2022/> | temperature2 = 18,800<ref name=Gomez2022/> }} {{Starbox detail|no_heading=y | component1 = κ Cen C | mass = 0.67<ref name=Anders2019/> | gravity = 4.65<ref name=Anders2019/> | radius = | luminosity = | temperature = 4,830<ref name=Anders2019/> }} {{Starbox catalog | names = {{odlist | B=κ Cen | CD=−41°9342 | FK5=553 | HD=132200 | HIP=73334 | HR=5576 | SAO=225344 | WDS=J14592-4206A }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = kap+Cen }} {{Starbox end}} '''Kappa Centauri''' is a [[triple star]] system in the southern [[constellation]] of [[Centaurus]]. Its name is a [[Bayer designation]] that is [[Romanization of Greek|Latinized]] from κ Centauri, and abbreviated Kappa Cen or κ Cen. With an [[apparent visual magnitude]] of +3.14,<ref name="apjs15_459"/> it can be viewed with the [[naked eye]] on a dark night. [[Parallax]] measurements place it at an estimated distance of {{Convert|400|ly|pc|abbr=off|lk=on}} from [[Earth]].<ref name=Gomez2022/>
==Characteristics== Kappa Centauri consists of an outer visual pair consisting of the components AB and C, and an inner pair consisting of the components A and B. The inner pair is a [[spectroscopic binary]] system where the presence of an orbiting companion is revealed by shifts in the [[absorption line]]s caused by the [[Doppler effect]]. They take 58 years to complete an orbit, have a small [[orbital eccentricity|eccentricity]] of 0.304, and are seen orbiting nearly edge-on.<ref name=Gomez2022/>
[[File:KapCenLightCurve.png|thumb|left|A [[light curve]] for Kappa Centauri, plotted from ''[[Transiting Exoplanet Survey Satellite|TESS]]'' data.<ref name=MAST/>]] The primary, component A, has about 8.4 times the [[Sun's mass]]<ref name=Gomez2022/> and four times the [[Sun's radius]].<ref name=an330_4_317/> It has a [[stellar classification]] of B2V,<ref name=Gomez2022/> indicating that it is in the [[main sequence]] stage of its [[stellar evolution]]. An [[effective temperature]] of {{Val|fmt=commas|20,900|ul=K}}<ref name=Gomez2022/> in the outer envelope is what gives it the blue-white hue of a B-type star.<ref name=csiro/> It is a candidate [[Beta Cephei variable]] that shows line-profile variations in its [[stellar spectrum|spectrum]]. However, the nature of the variability remains uncertain because of the binary nature of the system.<ref name=asp2002_204/>
The secondary, component B, is also a [[B-type main-sequence star]], of spectral class B3V. It has 4.4 times the [[Sun's mass]] and an effective temperature of {{Val|fmt=commas|18800|ul=K}}.<ref name=Gomez2022/>
The outer companion C is separated by 3.9" from the inner pair and has an estimated [[orbital period]] of 3,200 years.<ref name=Tokovinin2018/> It is an [[K-type main-sequence star]] with a spectral type K2V.<ref name=DD2017/> The star has 0.67 times the [[mass of the Sun]] and an [[effective temperature]] of 4,829 K.<ref name=Anders2019/>
This system is a [[proper motion]] member of the Upper Centaurus–Lupus sub-group in the [[Scorpius–Centaurus association|Scorpius–Centaurus]] [[Stellar association|OB association]], the nearest such co-moving association of massive stars to the Sun.<ref name=aaa216_1_44/>
==In Chinese astronomy== In [[Chinese astronomy|Chinese]], {{lang|zh|騎官}} ({{lang|zh-Latn|Qí Guān}}), meaning ''[[Root (Chinese constellation)|Imperial Guards]]'', refers to an asterism consisting of κ Centauri, [[Gamma Lupi|γ Lupi]], [[Delta Lupi|δ Lupi]], [[Beta Lupi|β Lupi]], [[Lambda Lupi|λ Lupi]], [[Epsilon Lupi|ε Lupi]], [[Mu Lupi|μ Lup]], [[Pi Lupi|π Lupi]], [[Omicron Lupi|ο Lupi]] and [[Alpha Lupi|α Lupi]].<ref>{{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> Consequently, the [[Chinese star names|Chinese name]] for κ Centauri itself is {{lang|zh|騎官三}} ({{lang|zh-Latn|Qí Guān sān}}, {{langx|en|the Third Star of Imperial Guards}}.).<ref>{{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> From this Chinese name, the name '''Ke Kwan''' has appeared.<ref name=Allen_1963/>
==See also== * [[Traditional Chinese star names#Centaurus|Traditional Chinese star names]]
==References== {{reflist|30em|refs=
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}}
{{Stars of Centaurus}}
<!-- Physical properties --> [[Category:B-type main-sequence stars]] [[Category:Beta Cephei variables]] [[Category:Spectroscopic binaries]] [[Category:Upper Centaurus Lupus]] <!-- Constellation & catalogues --> [[Category:Centaurus]] [[Category:Bayer objects|Centauri, Kappa]] [[Category:Bright Star Catalogue objects|5576]] [[Category:Durchmusterung objects]] [[Category:Henry Draper Catalogue objects|132200]] [[Category:Hipparcos objects|073334]]