Epsilon Apodis
 Location of ε Apodis (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Apus |
| Right ascension | 14h 22m 23.16467s[1] |
| Declination | –80° 06′ 32.2053″[1] |
| Apparent magnitude (V) | 5.06[2] |
| Characteristics | |
| Spectral type | B3 V[3] |
| U−B color index | –0.610[2] |
| B−V color index | –0.121[2] |
| Variable type | γ Cas[4] |
| Astrometry | |
| Radial velocity (Rv) | +4.5[5] km/s |
| Proper motion (μ) | RA: –9.51[1] mas/yr Dec.: –14.34[1] mas/yr |
| Parallax (π) | 5.06 ± 0.22[1] mas |
| Distance | 640 ± 30 ly (198 ± 9 pc) |
| Details | |
| Mass | 6.15 ± 0.71[6] M☉ |
| Radius | 3.9[7] R☉ |
| Luminosity | 1,614[6] L☉ |
| Surface gravity (log g) | 4.18[8] cgs |
| Temperature | 17,050[6] K |
| Metallicity [Fe/H] | –0.02[8] dex |
| Rotational velocity (v sin i) | 255[9] km/s |
| Age | 38.3 ± 4.4[10] Myr |
| Other designations | |
Epsilon Apodis (ε Aps, ε Apodis) is the Bayer designation for a star in the southern circumpolar constellation of Apus. It has an apparent visual magnitude of 5.06,[2] which is bright enough to be viewed from dark suburban skies. Based upon parallax measurements, it is at a distance of roughly 640 light-years (200 parsecs) from Earth.[1]
Based upon a stellar classification of B3 V,[3] this is a massive, B-type main sequence star that is generating energy through the fusion of hydrogen at its core. Epsilon Apodis has more than six[6] times the mass of the Sun and nearly four[7] times the Sun's radius. It is radiating 1,614[6] times as much luminosity as the Sun from its outer envelope at an effective temperature of 17,050 K.[6] At this heat, it has a blue-white glow that is a characteristic of B-type stars.[12]
It is spinning rapidly, with a projected rotational velocity of 255 km/s [9] giving a lower bound for the azimuthal velocity along the equator. Epsilon Apodis is classified as a Gamma Cassiopeiae type[4] variable star and its brightness varies between magnitudes 4.99 and 5.04.[13]
Naming
In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, 異雀 (Yì Què), meaning Exotic Bird, refers to an asterism consisting of ε Apodis, ζ Apodis, ι Apodis, β Apodis, γ Apodis, δ Octantis, δ1 Apodis, η Apodis and α Apodis. Consequently, ε Apodis itself is known as 異雀九 (Yì Què jiǔ, English: the Ninth Star of Exotic Bird.)[14]
References
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- ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
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- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 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.
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- ↑ 9.0 9.1 Lua error in package.lua at line 80: module 'strict' not found.
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- ↑ 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) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 29 日
