Iota Centauri

{{Short description|Star in the constellation Centaurus}} {{Starbox begin | name=ι Centauri }} {{Starbox image | image = {{Location mark | image=Centaurus IAU.svg | float=center | width=240 | position=right | mark=Red circle.svg | mark_width=10 | mark_link=ι Cen | x%=44.8 | y%=34.6 }} | caption=Location of ι Centauri (circled) }} {{Starbox observe | epoch = [[J2000.0]] | constell = [[Centaurus]]<ref name=Anderson2012/> | ra = {{RA|13|20|35.81737}}<ref name=aaa474_2_653/> | dec = {{DEC|−36|42|44.2447}}<ref name=aaa474_2_653/> | appmag_v = +2.73<ref name=clpl4_99/> }} {{Starbox character | type = [[main sequence]]<ref name=hu2023/> | class = A2 V<ref name=Anderson2012/> (kA1.5hA3mA3va)<ref name=aj132_1_161/> | b-v = +0.03<ref name=clpl4_99/> | u-b = +0.01<ref name=clpl4_99/> | variable = }} {{Starbox astrometry | radial_v = +0.1<ref name=scfs/> | prop_mo_ra = −341.11<ref name=aaa474_2_653/> | prop_mo_dec = −86.14<ref name=aaa474_2_653/> | parallax = 55.49 | p_error = 0.17 | parallax_footnote = <ref name=aaa474_2_653/> | absmag_v = +1.47<ref name=Anderson2012/> }} {{Starbox detail | mass = {{val|2.03|0.03}}<ref name=pearce/> | radius = {{solar radius calculator|type=logLT|1=1.36|logLerr=0.02|2=9160|Terr=70|decimals=2}}<ref name=pearce/>{{efn|name=rad}} | luminosity = {{val|22.91|1.08|1.03}}<ref name=pearce/> | temperature = {{val|9160|70|fmt=commas}}<ref name=pearce/> | gravity = 4.11<ref name=aaa490_1_297/> | metal_fe = –0.46<ref name=aaa490_1_297/> | rotational_velocity = 90.3<ref name=aaa531_A143/> | age_gyr = 0.35<ref name=apjl736_2_L32/> }} {{Starbox catalog | names = {{odlist | name=Kulou | B=ι Cen | CD=−36°8497 | GJ=508.1 | GJ2=9441 | FK5=496 | HD=115892 | HIP=65109 | HR=5028 | SAO=204371 }}<ref name=SIMBAD/> }} {{Starbox reference |Simbad=iot+Cen }} {{Starbox end}}

'''Iota Centauri''' is a [[star]] in the southern [[constellation]] of [[Centaurus]]. It has the proper name '''Kulou''';<ref name="IAU-CSN-new"/> ''Iota Centauri'' is its [[Bayer designation]], which is [[Romanization of Greek|Latinized]] from ι Centauri and is abbreviated Iota Cen or ι Cen. Based upon [[parallax]] measurements, it lies at a distance of approximately {{Convert|58.6|ly|pc|abbr=off|lk=on}} from [[Earth]].<ref name=aaa474_2_653/> Iota Centauri has an [[apparent visual magnitude]] of +2.73,<ref name=clpl4_99/> making it [[Bortle Dark-Sky Scale|easily visible]] to the naked eye.

The spectrum of ι Centauri matches a [[stellar classification]] of A2 V. It is an [[A-type main sequence star]] that is generating energy by the [[nuclear fusion]] of hydrogen in its core region. This energy is being radiated from the outer envelope of the star at an [[effective temperature]] of 9,160 K,<ref name=pearce/> giving the star a white hue.<ref name=csiro/> It has about 2 times the [[solar mass|Sun's mass]], 1.9 times the [[solar radius|Sun's radius]],<ref name=pearce/> and is roughly 350 million years old.<ref name=apjl736_2_L32/> The abundance of elements other than hydrogen and helium, what astronomers term the [[metallicity]], is only 35% of the abundance in the Sun.<ref name=aaa490_1_297/> A weak [[stellar magnetic field|magnetic field]] has been tentatively identified with a strength of {{nowrap|−77 ± 30 [[Gauss (unit)|G]]}}.<ref name=aaa446_3_1089/>

This star has an [[infrared excess|excess emission of infrared]] indicating it is surrounded by a circumstellar disk of dust, known as a [[debris disk]]. The disk is located within an orbital radius of six [[Astronomical Unit]]s from the star. The dust is unusually luminous for a star this age, suggesting that some process may have recently increased the amount of debris, such as collisions between [[planetesimal]]s. Alternatively, the planetesimals in this system may have unusual physical properties. As of 2011, a search for planets in this system has thus far been unsuccessful.<ref name=apjl736_2_L32/>

Iota Centauri appears to belong to the [[stellar kinematic group]] known as IC 2391. This is a group of around 16 co-moving stars that most likely originated in the same [[molecular cloud]] at least 45 million years ago.<ref name=aj140_3_713/>

==Nomenclature== In [[Chinese astronomy|Chinese]], {{lang|zh|柱}} ({{lang|zh-Latn|Zhǔ}}), meaning ''[[Horn (Chinese constellation)|Pillars]]'', refers to an asterism consisting of ι Centauri, [[Upsilon2 Centauri|υ2 Centauri]], [[Upsilon1 Centauri|υ1 Centauri]], [[V761 Centauri|a Centauri]], [[Psi Centauri|ψ Centauri]], [[4 Centauri]], [[3 Centauri]] and [[1 Centauri]].<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 ι Centauri itself is {{lang|zh|柱十一}} ({{lang|zh-Latn|Zhǔ shíyī}}, {{langx|en|the Eleventh Star of Pillars}}.)<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>

In older Chinese sources,<ref name="ASE"/> this star was a member of the ancient super-constellation Kulou (库楼, The Arsenal), in the area of modern [[Centaurus]] and [[Lupus (constellation)|Lupus]], dating back to the 2nd century BCE.<ref name="IAU-CSN-new"/> Later, [[Zeta Centauri|ζ Centauri]] was identified as the main star of Kulou.<ref name="ASE"/> The [[IAU Working Group on Star Names]] approved the name Kulou for this star on 17 February 2025 and it is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN-new"/>

==Notes== {{Notelist|notes=

{{Efn|name=rad|1=Calculated, using the [[Stefan-Boltzmann law]] and the star's [[effective temperature]] and luminosity, with respect to the [[Sun|solar]] nominal effective temperature of 5,772 [[Kelvin|K]]:<math display="block">\sqrt{\biggl(\frac{5,772}{9,160}\biggr)^4 \cdot 10^{1.36}} = 1.9\ R_\odot.</math>}}

}}

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}}

{{DEFAULTSORT:Iota Centauri}}  [[Category:A-type main-sequence stars]]  [[Category:Centaurus]] [[Category:Bayer objects|Centauri, Iota]] [[Category:Bright Star Catalogue objects|5028]] [[Category:Durchmusterung objects|CD-36 08497]] [[Category:Gliese and GJ objects|9441]] [[Category:Henry Draper Catalogue objects|115892]] [[Category:Hipparcos objects|65109]] [[Category:Stars with proper names|Kulou]]