Lambda Centauri
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, 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°. The nebula IC 2944 lies nearby.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 11h 35m 46.87908s |
| Declination | −63° 01′ 11.3965″ |
| Apparent magnitude (V) | +3.13 |
| Characteristics | |
| Spectral type | B9 III |
| U−B color index | −0.19 |
| B−V color index | −0.04 |
| Astrometry | |
| Radial velocity (Rv) | −1.4 km/s |
| Proper motion (μ) | RA: −34.270 mas/yr Dec.: −7.912 mas/yr |
| Parallax (π) | 6.9253 ± 0.3316 mas |
| Distance | 470 ± 20 ly (144 ± 7 pc) |
| Absolute magnitude (MV) | −2.35 |
| Details | |
| Mass | 4.5 M☉ |
| Radius | 5.5 R☉ |
| Luminosity | 739 L☉ |
| Surface gravity (log g) | 3.04 cgs |
| Temperature | 9,880 K |
| Metallicity [Fe/H] | +0.41 dex |
| Rotational velocity (v sin i) | 183 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Lambda Centauri is a B-type giant star with a stellar classification of B9 III (although it has also been classified as A1 III). It has about 5.5 times the radius of the Sun and is rotating rapidly with a projected rotational velocity of 183 km/s. The latter is giving the star an oblate shape with an equatorial bulge that is 17% larger than the polar radius. The star's outer atmosphere has an effective temperature of 9,880 K, 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.