Eta Centauri
 Location of η Centauri (circled) |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Centaurus |
| Right ascension | 14h 35m 30.42416s[1] |
| Declination | −42° 09′ 28.1708″[1] |
| Apparent magnitude (V) | +2.35[2] (2.30 - 2.41[3]) |
| Characteristics | |
| Spectral type | B1.5 Vne[4] |
| U−B color index | −0.862[2] |
| B−V color index | −0.215[2] |
| Variable type | γ Cassiopeiae[3] |
| Astrometry | |
| Radial velocity (Rv) | –0.2[5] km/s |
| Proper motion (μ) | RA: −34.73[1] mas/yr Dec.: −32.72[1] mas/yr |
| Parallax (π) | 10.67 ± 0.21[1] mas |
| Distance | 306 ± 6 ly (94 ± 2 pc) |
| Details | |
| Mass | 12.0 ± 0.3[6] M☉ |
| Radius | 5-6 R☉ |
| Luminosity | 8,700[4] L☉ |
| Surface gravity (log g) | 3.20[7] cgs |
| Temperature | 25,700[4] K |
| Rotational velocity (v sin i) | 330[4] km/s |
| Age | 5.6 ± 1.0[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta Centauri (η Cen, η Centauri) is a star in the southern constellation of Centaurus. It has an apparent visual magnitude of +2.35[2] and is located at a distance of around 306 light-years (94 parsecs).[1] In traditional Chinese astronomy, Eta Centauri was known as 庫樓二[9] (meaning: the Second (Star) of Koo Low).[10]
The stellar classification of this star is B1.5 Vne,[4] indicating that it is a B-type main sequence star. The 'n' suffix means that the absorption lines are broadened from rapid rotation. It has a projected rotational velocity of 330 km s−1[4] and completes a full rotation in less than a day. This is a Be star as shown by the 'e' suffix,[11] which means it has variable emissions in its hydrogen spectral lines. This emission can be modeled by a decretion disk of gas that has been ejected from the star and now follows a near Keplerian orbit around the central body.[12] Finally it is slightly variable, and classified as a Gamma Cassiopeiae variable star with multiple periods of variability.[3]
Eta Centauri has about 12[6] times the mass of the Sun, placing it above the dividing line between stars that evolve into white dwarfs and those that turn into supernovae. It is radiating 8,700[4] times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 25,700 K.[4] This heat causes the star to glow with the blue-white hue common to B-type stars.[13] Eta Centauri 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.[7]
See also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 3.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 6.0 6.1 6.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 7.0 7.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
External links
- Eta Centauri by Jim Kaler.
