# Kappa Centauri

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Variable binary star system in the constellation Centaurus

κ Centauri Location of κ Centauri (circled) Observation data Epoch J2000.0 Equinox ICRS Constellation Centaurus κ Cen AB Right ascension 14h 59m 09.6849s[1] Declination −42° 06′ 15.107″[1] Apparent magnitude (V) +3.14[2] (3.34 + 4.71)[3] κ Cen C Right ascension 14h 59m 10.0318s[4] Declination −42° 06′ 14.602″[4] Apparent magnitude (V) 11.5[5] Characteristics κ Cen AB Evolutionary stage main sequence Spectral type B2V + B3V[3] U−B color index −0.805[2] B−V color index −0.204[2] Variable type Candidate β Cep[6] κ Cen C Evolutionary stage main sequence[7] Spectral type K2V[7] Astrometry κ Cen AB Radial velocity (Rv) +8.0[8] km/s Proper motion (μ) RA: −17.62 mas/yr[1] Dec.: −22.51 mas/yr[1] Parallax (π) 8.14±0.33 mas[3] Distance 400 ± 20 ly (123 ± 5 pc) Absolute magnitude (MV) −2.2[9] κ Cen C Proper motion (μ) RA: −18.769 mas/yr[4] Dec.: −23.688 mas/yr[4] Parallax (π) 7.4667±0.0994 mas[4] Distance 437 ± 6 ly (134 ± 2 pc) Orbit[3] Primary κ Cen A Name κ Cen B Period (P) 58.52±1.50 years Semi-major axis (a) 0.287″±0.008″ Eccentricity (e) 0.304±0.009 Inclination (i) 90.9±0.5° Longitude of the node (Ω) 156.1±0.5° Periastron epoch (T) 2011.10±0.30 Argument of periastron (ω) (secondary) 215.1±2.0° Details κ Cen A Mass 8.38±0.27[3] M☉ Radius 4.4±0.7[10] R☉ Luminosity 2,500[10] L☉ Surface gravity (log g) 4.02±0.20[10] cgs Temperature 20,900[3] K Rotational velocity (v sin i) 10[11] km/s Age 18.2±3.2[12] Myr κ Cen B Mass 4.41±0.36[3] M☉ Temperature 18,800[3] K κ Cen C Mass 0.67[13] M☉ Surface gravity (log g) 4.65[13] cgs Temperature 4,830[13] K Other designations κ Cen, CD−41°9342, FK5 553, HD 132200, HIP 73334, HR 5576, SAO 225344, WDS J14592-4206A[14] Database references SIMBAD data

**Kappa Centauri** is a [triple star](/source/Triple_star) system in the southern [constellation](/source/Constellation) of [Centaurus](/source/Centaurus). Its name is a [Bayer designation](/source/Bayer_designation) that is [Latinized](/source/Romanization_of_Greek) from κ Centauri, and abbreviated Kappa Cen or κ Cen. With an [apparent visual magnitude](/source/Apparent_visual_magnitude) of +3.14,[2] it can be viewed with the [naked eye](/source/Naked_eye) on a dark night. [Parallax](/source/Parallax) measurements place it at an estimated distance of 400 [light-years](/source/Light-year) (120 [parsecs](/source/Parsec)) from [Earth](/source/Earth).[3]

## Characteristics

Kappa Centauri consists of an outer visual pair consisting of the components AB and C, and an inner pair consisting of the components A and B. The inner pair is a [spectroscopic binary](/source/Spectroscopic_binary) system where the presence of an orbiting companion is revealed by shifts in the [absorption lines](/source/Absorption_line) caused by the [Doppler effect](/source/Doppler_effect). They take 58 years to complete an orbit, have a small [eccentricity](/source/Orbital_eccentricity) of 0.304, and are seen orbiting nearly edge-on.[3]

A [light curve](/source/Light_curve) for Kappa Centauri, plotted from *[TESS](/source/Transiting_Exoplanet_Survey_Satellite)* data.[15]

The primary, component A, has about 8.4 times the [Sun's mass](/source/Sun's_mass)[3] and four times the [Sun's radius](/source/Sun's_radius).[10] It has a [stellar classification](/source/Stellar_classification) of B2V,[3] indicating that it is in the [main sequence](/source/Main_sequence) stage of its [stellar evolution](/source/Stellar_evolution). An [effective temperature](/source/Effective_temperature) of 20,900 [K](/source/Kelvin)[3] in the outer envelope is what gives it the blue-white hue of a B-type star.[16] It is a candidate [Beta Cephei variable](/source/Beta_Cephei_variable) that shows line-profile variations in its [spectrum](/source/Stellar_spectrum). However, the nature of the variability remains uncertain because of the binary nature of the system.[6]

The secondary, component B, is also a [B-type main-sequence star](/source/B-type_main-sequence_star), of spectral class B3V. It has 4.4 times the [Sun's mass](/source/Sun's_mass) and an effective temperature of 18,800 [K](/source/Kelvin).[3]

The outer companion C is separated by 3.9" from the inner pair and has an estimated [orbital period](/source/Orbital_period) of 3,200 years.[5] It is an [K-type main-sequence star](/source/K-type_main-sequence_star) with a spectral type K2V.[7] The star has 0.67 times the [mass of the Sun](/source/Mass_of_the_Sun) and an [effective temperature](/source/Effective_temperature) of 4,829 K.[13]

This system is a [proper motion](/source/Proper_motion) member of the Upper Centaurus–Lupus sub-group in the [Scorpius–Centaurus](/source/Scorpius%E2%80%93Centaurus_association) [OB association](/source/Stellar_association), the nearest such co-moving association of massive stars to the Sun.[9]

## In Chinese astronomy

In [Chinese](/source/Chinese_astronomy), 騎官 (*Qí Guān*), meaning *[Imperial Guards](/source/Root_(Chinese_constellation))*, refers to an asterism consisting of κ Centauri, [γ Lupi](/source/Gamma_Lupi), [δ Lupi](/source/Delta_Lupi), [β Lupi](/source/Beta_Lupi), [λ Lupi](/source/Lambda_Lupi), [ε Lupi](/source/Epsilon_Lupi), [μ Lup](/source/Mu_Lupi), [π Lupi](/source/Pi_Lupi), [ο Lupi](/source/Omicron_Lupi) and [α Lupi](/source/Alpha_Lupi).[17] Consequently, the [Chinese name](/source/Chinese_star_names) for κ Centauri itself is 騎官三 (*Qí Guān sān*, English: the Third Star of Imperial Guards.).[18] From this Chinese name, the name **Ke Kwan** has appeared.[19]

## See also

- [Traditional Chinese star names](/source/Traditional_Chinese_star_names#Centaurus)

## References

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v t e Constellation of Centaurus List of stars in Centaurus Centaurus in Chinese astronomy Stars Bayer α A (Rigil Kentaurus) B (Toliman) C (Proxima Centauri) β (Hadar) γ δ ε ζ (Leepwal) η θ (Menkent) ι (Kulou) κ λ μ ν (Heng) ξ1 ξ2 ο1 ο2 π ρ σ τ υ1 υ2 φ χ ψ x1 x2 C3 D E F G H J K M N Q Flamsteed 1 (i) 2 (g) 3 (k) 4 (h) Variable R T V Y RR SV SX BV DY UY V346 V553 V744 V752 V761 (a) V763 (C1) V766 V779 (Krzemiński's star) V803 V810 V816 (Przybylski's Star) V831 V842 V885 V886 V863 V1032 V1369 V1400 V1935 HR 4460 (A) 4466 (C2) 4499 4522 4523 4537 (j) 4546 (B) 4721 4748 (u) 4796 4817 (l) 4831 (w) 4874 (p) 4888 (e) 4889 (n) 4940 (f) 4979 4989 5006 (r) 5041 (m) 5089 (d) 5174 (z) 5222 (y) 5224 5241 5297 5358 (v) 5371 5471 (b) 5485 (c1) 5489 (c2) HD 97413 98176 100453 101581 101930 102117 (Uklun) 103197 107914 108236 109749 110113 113538 113766 114386 114729 115600 116434 (Matza) 117207 117618 (Dofida) 117939 120411 121228 121504 124448 (Popper's Star) 125072 125595 131399 Other 2MASS J1126−5003 2M1207 Gaia BH2 HD 131399 Ab PSR B1259−63 PSR J1311−3430 TOI-763 WASP-15 (Nyamien) WASP-41 WASP-42 WASP-167/KELT-13 Exoplanets 2M1207b b Centauri b HD 101930 b HD 102117 b (Leklsullun) HD 103197 b HD 109749 b HD 113538 b c HD 114386 b HD 114729 b HD 117207 b HD 117618 b (Noifasui) HD 121504 b HIP 65426 b (Najsakopajk) HIP 67522 b NGTS-13b Proxima Centauri b c d WASP-15b (Asye) Star clusters NGC 3766 4230 4507 5281 5286 5316 5460 5617 5662 Other IC 2944 ω Centauri Scorpius–Centaurus association Stock 16 Nebulae NGC 3918 5307 Other Boomerang Nebula Fleming 1 G292.0+1.8 G306.3-0.9 Gum 41 IC 2944 IRAS 13208−6020 RCW 79 RCW 86 Southern Crab Nebula SuWt 2 Galaxies NGC 3557 3568 3749 3783 4444 4603 4622 4650A 4683 4696 4706 4709 4729 4730 4743 4744 4909 4930 4945 4976 5011 A 5026 5064 5082 5090 5091 5102 5114 5121 5128 (Centaurus A) 5161 5206 5253 5266 5291 5398 5408 5419 5483 5516 Other ESO 269-57 ESO 325-4 ESO 383-76 ESO 444-46 Fourcade-Figueroa Object IC 3370 IC 4214 IC 4329A IRAS 13224−3809 J1144−4308 LEDA 677373 PKS 1144−379 PKS 1353−341 PKS 1424−418 Galaxy clusters Abell S740 Centaurus Cluster Shapley Supercluster Astronomical events GW190521 SN 185 SN 1895B (Z) SN 1972E SN 1986G J1407b SN 2019so Category

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Adapted from the Wikipedia article [Kappa Centauri](https://en.wikipedia.org/wiki/Kappa_Centauri) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Kappa_Centauri?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.