Epsilon Apodis

ε 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 mas[1]
Distance640 ± 30 ly
(198 ± 9 pc)
Absolute magnitude (MV)−1.41[6]
Details
Mass6.15±0.71[7] M☉
Radius3.9[8] R☉
Luminosity1,614[7] L☉
Surface gravity (log g)4.18[9] cgs
Temperature17,050[7] K
Metallicity [Fe/H]−0.02[9] dex
Rotational velocity (v sin i)255[10] km/s
Age38.3±4.4[11] Myr
Other designations
ε Aps, CD–79 559, HD 124771, HIP 70248, HR 5336, SAO 257142.[12]
Database references
SIMBADdata

Epsilon Apodis, Latinized from 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]

A light curve for Epsilon Apodis, plotted from Hipparcos data[13]

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[7] times the mass of the Sun and nearly four[8] times the Sun's radius. It is radiating 1,614[7] times as much luminosity as the Sun from its outer envelope at an effective temperature of 17,050 K.[7] At this heat, it has a blue-white glow that is a characteristic of B-type stars.[14]

It is spinning rapidly, with a projected rotational velocity of 255 km/s[10] 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.[15]

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