Epsilon Apodis
Star in the constellation Apus
From Wikipedia, the free encyclopedia
Epsilon Apodis is a star in the southern circumpolar constellation of Apus. Its identifier is a Bayer designation that is Latinized from ε Apodis, and abbreviated Eps Aps or ε Aps, respectively. This star has an apparent visual magnitude of 5.06,[3] 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.[2] The star is drifting further away with a heliocentric radial velocity of +4.5 km/s.[6]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Apus[1] |
| Right ascension | 14h 22m 23.16467s[2] |
| Declination | −80° 06′ 32.2053″[2] |
| Apparent magnitude (V) | 5.06[3] |
| Characteristics | |
| Spectral type | B3 V[4] |
| U−B color index | −0.610[3] |
| B−V color index | −0.121[3] |
| Variable type | γ Cas[5] |
| Astrometry | |
| Radial velocity (Rv) | +4.5±4.2[6] km/s |
| Proper motion (μ) | RA: −9.51[2] mas/yr Dec.: −14.34[2] mas/yr |
| Parallax (π) | 5.06±0.22 mas[2] |
| Distance | 640 ± 30 ly (198 ± 9 pc) |
| Absolute magnitude (MV) | −1.41[1] |
| Details | |
| Mass | 6.15±0.71[7] M☉ |
| Radius | 4.30±0.09[8] R☉ |
| Luminosity | 1,614[7] L☉ |
| Surface gravity (log g) | 3.50±0.04[8] cgs |
| Temperature | 17,100±171[8] K |
| Metallicity [Fe/H] | −0.02[9] dex |
| Rotational velocity (v sin i) | 150±3[8] km/s |
| Age | 38.3±4.4[10] Myr |
| Other designations | |
| ε Aps, CD−79°559, HD 124771, HIP 70248, HR 5336, SAO 257142[11] | |
| Database references | |
| SIMBAD | data |
Based upon a stellar classification of B3 V,[4] 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[7] times the mass of the Sun and over four[8] times the Sun's radius. It is radiating 1,614[7] times as much luminosity as the Sun from its photosphere at an effective temperature of 17,100 K.[8] At this heat, it has a blue-white glow that is a characteristic of B-type stars.[13]
Epsilon Apodis is spinning rapidly, with a projected rotational velocity of 150 km/s[8] giving a lower bound for the azimuthal velocity along the equator. Epsilon Apodis is classified as a Gamma Cassiopeiae type[5] variable star and its brightness varies between magnitudes 4.99 and 5.04.[14]
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.)[15]