Epsilon Centauri
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 430 light-years (130 parsecs) from Earth.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 13h 39m 53.25774s |
| Declination | −53° 27′ 59.0081″ |
| Apparent magnitude (V) | +2.30 (2.29 - 2.31) |
| Characteristics | |
| Spectral type | B1 III |
| U−B color index | −0.92 |
| B−V color index | −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 | 430 ± 30 ly (131 ± 8 pc) |
| Absolute magnitude (MV) | –3.9 |
| Details | |
| Mass | 11.60 ± 1.06 M☉ |
| Luminosity | 15,217 L☉ |
| 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 |
| Other designations | |
| Database references | |
| SIMBAD | data |
In Chinese, 南門 (Nán Mén), meaning Southern Gate, refers to an asterism consisting of ε Centauri and α Centauri. Consequently, the Chinese name for ε Centauri itself is 南門一 (Nán Mén yī, English: the First Star of Southern Gate.)
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.