Epsilon Centauri
Star in the constellation Centaurus
From Wikipedia, the free encyclopedia
Epsilon Centauri is a star in the southern constellation of Centaurus. Its name is a Bayer designation that is Latinized from ε Centauri, and abbreviated Epsilon Cen or ε Cen. This 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[1] |
| Right ascension | 13h 39m 53.25774s[2] |
| Declination | −53° 27′ 59.0081″[2] |
| Apparent magnitude (V) | 2.29 - 2.31[3] |
| Characteristics | |
| Spectral type | B1 III[4] |
| U−B color index | −0.92[5] |
| B−V color index | −0.22[5] |
| Variable type | β Cep[3] |
| Astrometry | |
| Radial velocity (Rv) | +3.0[6] km/s |
| Proper motion (μ) | RA: −15.30[2] mas/yr Dec.: −11.72[2] mas/yr |
| Parallax (π) | 7.63±0.48 mas[2] |
| Distance | 430 ± 30 ly (131 ± 8 pc) |
| Absolute magnitude (MV) | −3.29[1] |
| Details | |
| Mass | 8.2[7] M☉ |
| Radius | 5.8[8] R☉ |
| Luminosity | 16,137[8] L☉ |
| Surface gravity (log g) | 3.88[8] cgs |
| Temperature | 24,937[8] K |
| Metallicity [Fe/H] | −0.14±0.10[9] dex |
| Rotational velocity (v sin i) | 140[10] km/s |
| Age | 16.3[11] Myr |
| Other designations | |
| ε Cen, CPD−52°6655, FK5 504, HD 118716, HIP 66657, HR 5132, SAO 241047[12] | |
| Database references | |
| SIMBAD | data |
In Chinese, 南門 (Nán Mén), meaning Southern Gate, refers to an asterism consisting of ε Centauri and α Centauri.[13] Consequently, the Chinese name for ε Centauri itself is 南門一 (Nán Mén yī, English: the First Star of Southern Gate.)[14]
ε Centauri is a massive star with 8.2 times the mass of the Sun.[7] The spectrum matches a stellar classification of B1 III,[4] indicating this is an evolved giant star. It is radiating more than 16,000 times the luminosity of the Sun[8] from its outer atmosphere at an effective temperature of about 25,000 K,[8] giving it the blue-white hue of a B-type star.[16] It 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.[9] 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.[17] Epsilon Centauri is a relatively young star, with an age of around 16 million years.[18]