{{Short description|Star in the constellation Centaurus}} {{Starbox begin | name = λ 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=λ Cen |x=795|y=966 }} |caption=Location of λ Centauri, circled, lower right }} {{Starbox observe | epoch = [[J2000.0]] | constell = [[Centaurus]] | ra = {{RA|11|35|46.878}}<ref name=GaiaDR3/> | dec = {{DEC|−63|01|11.41}}<ref name=GaiaDR3/> | appmag_v = +3.13<ref name=clpl4/> }} {{Starbox character | class = B9 III<ref name=houk1979/><ref name=mnras389_2_869/> | b-v = −0.04<ref name=clpl4/> | u-b = −0.19<ref name=clpl4/> | variable = }} {{Starbox astrometry | radial_v = −1.4<ref name=rgcrv/> | prop_mo_ra = −33.863 | prop_mo_dec = −7.236 | pm_footnote = <ref name=GaiaDR3/> | parallax = 8.2770 | p_error = 0.2537 | parallax_footnote = <ref name=GaiaDR3/> | absmag_v = −2.35<ref name=eggen/> }} {{Starbox detail | mass = 4.5<ref name=Kaler2012/> | radius = 5.5<ref name=mnras189_601/> | metal_fe = +0.41<ref name=erspamer/> | gravity = 3.04<ref name=erspamer/> | age_myr = | luminosity = 739<ref name=mcdonald/> | temperature = 9,880<ref name=aaa501_1_297/> | rotational_velocity = 183<ref name=aaa393_897/> }} {{Starbox catalog | names = {{odlist | B=λ Cen, lambda Cen | CP=−62°2127 | FK5=436 | HD=100841 | HIP=56561 | HR=4467 | SAO=251472 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = lam+Cen }} {{Starbox end}} [[File:IC 2944.jpg|thumb|left|upright=1.0|λ Centauri in [[IC 2944]], with IC 2948 below left and IC 2872 above right]] '''Lambda Centauri''' is a [[star]] in the southern [[circumpolar constellation]] of [[Centaurus]]. Its name is a [[Bayer designation]] that is [[Romanization of Greek|Latinized]] from λ Centauri, and abbreviated Lambda Cen or λ Cen. The star has an [[apparent visual magnitude]] of +3.13,<ref name=clpl4/> which is bright enough to be seen with the [[naked eye]] from the [[Southern Hemisphere]] and places it among the brighter members of this constellation. The star is close enough that its distance can be determined directly using the [[stellar parallax|parallax]] technique, which gives a value of approximately 390 [[light year]]s (121 [[parsec|pc]]) from the [[Sun]]. Although a putative solitary star, it has a candidate proper motion companion at an [[angular separation]] of 0.73 [[arcsecond]]s along a [[position angle]] of 135°.<ref name=aaa382_92/> The [[nebula]] [[IC 2944]] lies nearby.<ref name=Baume_et_al_2014/>
Lambda Centauri is a [[Stellar classification|B-type]] [[giant star]]<ref name=omeara2002/> with a [[stellar classification]] of B9 III<ref name=houk1979/> (although it has also been classified as A1 III).<ref name=aaa501_1_297/> It has about 5.5<ref name=mnras189_601/> times the radius of the [[Sun]] and is rotating rapidly with a [[projected rotational velocity]] of {{nowrap|183 km/s}}.<ref name=aaa393_897/> The latter is giving the star an [[oblate spheroid|oblate]] shape with an [[equatorial bulge]] that is 17% larger than the polar radius.<ref name=belle2012/> The star's [[stellar atmosphere|outer atmosphere]] has an [[effective temperature]] of 9,880 K,<ref name=aaa501_1_297/> giving it a blue-white hue.
Based upon the position and movement of this star through space, it is a likely member of the [[Gould Belt]]. In particular, it belongs to the Lower Centaurus–Crux (LCC) group of the [[Scorpius–Centaurus association]], which is the nearest [[OB association]] to the Sun. This is a loose grouping of stars that share a common motion through space and therefore formed in the same [[molecular cloud]]. The LCC group has an estimated age of 16–20 million years and is centered on a mean distance of {{Convert|380|ly|pc|abbr=off}} from Earth.<ref name=al33_9_571/>
==Gallery== <gallery> Lambda Centauri Star.jpg|Lambda Centauri and surrounding nebula [[IC 2944]] Yb southern cross cc.tif|[[Crux]] with λ Centauri (top) and its associated nebulosity visible </gallery>
==References== {{Reflist|refs=
<ref name=GaiaDR3>{{Cite Gaia DR3 | 5333974693006467328 | mode=cs2 | postscript=. | access-date=2025-12-15 }}</ref>
<ref name=SIMBAD>{{cite simbad | title=lam Cen | mode=cs2 | access-date=2021-06-27 | postscript=. }}</ref>
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<ref name=erspamer>{{citation | postscript=. |bibcode=2003A&A...398.1121E |title=Automated spectroscopic abundances of a and F-type stars using echelle spectrographs. II. Abundances of 140 A-F stars from ELODIE |journal=Astronomy and Astrophysics |volume=398 |issue=3 |pages=1121–1136 |last1=Erspamer |first1=D. |last2=North |first2=P. |year=2003 |doi=10.1051/0004-6361:20021711 |arxiv = astro-ph/0210065 |s2cid=1109164}}</ref>
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<ref name=belle2012>{{citation | title=Interferometric observations of rapidly rotating stars | last1=Belle | first1=G. T. | journal=The Astronomy and Astrophysics Review | volume=20| page=51 | year=2012 | issue=1 | doi=10.1007/s00159-012-0051-2 | bibcode=2012A&ARv..20...51V | arxiv=1204.2572 | s2cid=119273474 | postscript=. }}</ref>
<ref name=Kaler2012>{{citation | title=Lambda Centauri | first=James B. | last=Kaler | author-link=James B. Kaler | date=May 25, 2012 | work=STARS | url=http://stars.astro.illinois.edu/sow/lambdacen.html | access-date=2021-06-29 | postscript=. }}</ref>
<ref name=Baume_et_al_2014>{{citation | title=A deep and wide-field view at the IC 2944/2948 complex in Centaurus* | display-authors=1 | last1=Baume | first1=G. | last2=Rodríguez | first2=M. J. | last3=Corti | first3=M. A. | last4=Carraro | first4=G. | last5=Panei | first5=J. A. | journal=Monthly Notices of the Royal Astronomical Society | volume=443 | issue=1 | pages=411–422 | date=September 2014 | doi=10.1093/mnras/stu1108 | doi-access=free | arxiv=1406.0708 | bibcode=2014MNRAS.443..411B | postscript=. }}</ref>
}}
{{Stars of Centaurus}}
{{DEFAULTSORT:Lambda Centauri}} <!-- Physical properties --> [[Category:B-type giants]] [[Category:Lower Centaurus Crux]] [[Category:Population I stars]] [[Category:Gould Belt]] <!-- Constellation & catalogues --> [[Category:Centaurus]] [[Category:Bayer objects|Centauri, Lambda]] [[Category:Bright Star Catalogue objects|4467]] [[Category:Durchmusterung objects]] [[Category:Henry Draper Catalogue objects|100841]] [[Category:Hipparcos objects|056561]]