Kappa Centauri
 Location of κ Centauri (circled) |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Centaurus |
| Right ascension | 14h 59m 09.68494s[1] |
| Declination | −42° 06′ 15.1069″ |
| Apparent magnitude (V) | +3.14[2] |
| Characteristics | |
| Spectral type | B2 IV[3] |
| U−B color index | −0.805[2] |
| B−V color index | −0.204[2] |
| Variable type | Candidate β Cep[4] |
| Astrometry | |
| Radial velocity (Rv) | +8.0[5] km/s |
| Proper motion (μ) | RA: −17.62[1] mas/yr Dec.: −22.51[1] mas/yr |
| Parallax (π) | 8.51 ± 0.54[1] mas |
| Distance | 380 ± 20 ly (118 ± 7 pc) |
| Absolute magnitude (MV) | –2.2[6] |
| Details | |
| κ Cen A | |
| Mass | 7.2 ± 0.5[3] M☉ |
| Radius | 4.4 ± 0.7[3] R☉ |
| Luminosity | 2,500[3] L☉ |
| Surface gravity (log g) | 4.02 ± 0.20[3] cgs |
| Temperature | 19,800 ± 900[3] K |
| Rotational velocity (v sin i) | 10[7] km/s |
| Age | 18.2 ± 3.2[8] Myr |
| κ Cen B | |
| Mass | 5[9] M☉ |
| Other designations | |
Kappa Centauri (κ Cen, κ Centauri) is a binary star in the southern constellation of Centaurus. With an apparent visual magnitude of +3.14,[2] it can be viewed with the naked eye on a dark night. Parallax measurements place it at an estimated distance of 380 light-years (120 parsecs) from Earth.[1]
This is a spectroscopic binary system where the presence of an orbiting companion is revealed by shifts in the absorption lines caused by the Doppler effect. The primary component is a huge star, with about seven times the Sun's mass and four times the Sun's radius.[3] It has a stellar classification of B2 IV,[3] indicating that it is in the subgiant stage of its stellar evolution. An effective temperature of 19,800 K[3] in the outer envelope is what gives it the blue-white hue of a B-type star.[11]
The primary is a candidate Beta Cephei variable that shows line-profile variations in its spectrum. However, the nature of the variability remains uncertain because of the binary nature of the system.[4] As of 2007, the secondary component was separated from the primary by 0.128 arcseconds at a position angle of 156°. It has about 68% of the mass of the primary.[9] This system is a proper motion member of the Upper-Centaurus Lupus sub-group in the Scorpius-Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.[6]
In Chinese, 騎官 (Qí Guān), meaning Imperial Guards, refers to an asterism consisting of κ Centauri, γ Lupi, δ Lupi, β Lupi, λ Lupi, ε Lupi, μ Lup, π Lupi, ο Lupi and α Lupi.[12] Consequently, κ Centauri itself is known as 騎官三 (Qí Guān sān, English: the Third Star of Imperial Guards.).[13] From this Chinese name, the name Ke Kwan was appeared.[14]
See also
References
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- ↑ (Chinese) 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.
- ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 25 日
- ↑ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Centaurus
