Lambda Centauri

λ Centauri
Location of λ Centauri, circled, lower right
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Centaurus
Right ascension 11h 35m 46.87908s[1]
Declination −63° 01′ 11.3965″[1]
Apparent magnitude (V) +3.13[2]
Characteristics
Spectral type B9 III[3][4]
U−B color index −0.19[2]
B−V color index −0.04[2]
Astrometry
Radial velocity (Rv)−1.4[5] km/s
Proper motion (μ) RA: −34.270[1] mas/yr
Dec.: −7.912[1] mas/yr
Parallax (π)6.9253 ± 0.3316 mas[1]
Distance470 ± 20 ly
(144 ± 7 pc)
Absolute magnitude (MV)−2.35[6]
Details
Mass4.5[7] M☉
Radius5.5[8] R☉
Luminosity739[9] L☉
Surface gravity (log g)3.04[10] cgs
Temperature9,880[11] K
Metallicity [Fe/H]+0.41[10] dex
Rotational velocity (v sin i)183[12] km/s
Other designations
λ Cen, lam Cen, CPD−62°2127, FK5 436, HD 100841, HIP 56561, HR 4467, SAO 251472[13]
Database references
SIMBADdata
λ Centauri in IC 2944, with IC 2948 below left and IC 2872 above right

Lambda Centauri, Latinized from λ Centauri, is a star in the southern circumpolar constellation of Centaurus. It has an apparent visual magnitude of +3.13,[2] 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 parallax technique, which gives a value of approximately 470 light-years (140 parsecs) from the Sun. Although a putative solitary star, it has a candidate proper motion companion at an angular separation of 0.73 arcseconds along a position angle of 135°.[14] The nebula IC 2944 lies nearby.[15]

Lambda Centauri is a B-type giant star[16] with a stellar classification of B9 III[3] (although it has also been classified as A1 III).[11] It has about 5.5[8] times the radius of the Sun and is rotating rapidly with a projected rotational velocity of 183 km/s.[12] The latter is giving the star an oblate shape with an equatorial bulge that is 17% larger than the polar radius.[17] The star's outer atmosphere has an effective temperature of 9,880 K,[11] 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 380 light-years (120 parsecs) from Earth.[18]

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  15. ^ Cite error: The named reference Baume_et_al_2014 was invoked but never defined (see the help page).
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