Epsilon Centauri

ε Centauri

Template:Location mark Location of ε Centauri (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Centaurus
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	+2.30 (2.29 - 2.31)
Characteristics
Spectral type	B1 III
U−B Template:Engvar	−0.92
B−V Template:Engvar	−0.22
Variable type	β Cep
Astrometry
Radial velocity (Rv)	+3.0 km/s
Proper motion (μ)	RA: −15.30 mas/yr Dec.: −11.72 mas/yr
Parallax (π)	7.63±0.48 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	–3.9
Details
Mass	11.60 ± 1.06 Template:Solar mass
Radius	Template:Solar radius calculatorTemplate:Efn Template:Solar radius
Luminosity	15,217 Template:Solar luminosity
Surface gravity (log g)	3.68 cgs
Temperature	24,000 K
Metallicity [Fe/H]	–0.14 ± 0.10 dex
Rotational velocity (v sin i)	160 km/s
Age	15.8 ± 5.7 Myr
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
CP−52 6655, FK5 504, HD 118716, HIP 66657, HR 5132, SAO 241047.
Database references
SIMBAD	data

Epsilon Centauri (ε Cen, ε Centauri) is a star in the southern constellation of Centaurus. It is one of the brightest stars in the constellation with a slightly variable apparent visual magnitude of +2.30. Parallax measurements put it at a distance of around from Earth.

In Chinese, (), meaning Southern Gate, refers to an asterism consisting of ε Centauri and α Centauri. Consequently, the Chinese name for ε Centauri itself is (, Template:Langx.)

File:EpsilonCenLightCurve.png

A yellow-light light curve for Epsilon Centauri, adapted from Shobbrook (1972)

ε Centauri is a massive star with nearly 12 times the mass of the Sun. The spectrum matches a stellar classification of B1 III, indicating this is an evolved giant star. It is radiating more than 15,000 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 24,000 K, giving it the blue-white hue of a B-type star. This is classified as a Beta Cephei type variable star with a primary period of 0.16961 days (4 hours 4 minutes), completing 5.9 cycles per day. During each cycle, the brightness of the star varies from apparent magnitude +2.29 to +2.31.

This star is a proper motion member of the Lower Centaurus–Crux sub-group in the Scorpius–Centaurus OB association, the nearest such association of co-moving massive stars to the Sun. Epsilon Centauri is a relatively young star, with an age of around 16 million years.

The IAU has not assigned a proper name to this star.