Kappa Centauri
Kappa Centauri is a triple star system in the southern constellation of Centaurus. Its name is a Bayer designation that is Latinized from κ Centauri, and abbreviated Kappa Cen or κ Cen. With an apparent visual magnitude of +3.14, it can be viewed with the naked eye on a dark night. Parallax measurements place it at an estimated distance of from Earth.
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 system where the presence of an orbiting companion is revealed by shifts in the absorption lines caused by the Doppler effect. They take 58 years to complete an orbit, have a small eccentricity of 0.304, and are seen orbiting nearly edge-on.File:KapCenLightCurve.png|thumb|left|A light curve for Kappa Centauri, plotted from TESS data.
The primary, component A, has about 8.4 times the Sun's mass and four times the Sun's radius. It has a stellar classification of B2V, indicating that it is in the main sequence stage of its stellar evolution. An effective temperature of in the outer envelope is what gives it the blue-white hue of a B-type star. It 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.
The secondary, component B, is also a B-type main-sequence star, of spectral class B3V. It has 4.4 times the Sun's mass and an effective temperature of.
The outer companion C is separated by 3.9" from the inner pair and has an estimated orbital period of 3,200 years. It is an K-type main-sequence star with a spectral type K2V. The star has 0.67 times the mass of the Sun and an effective temperature of 4,829 K.
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.