Kappa Aquilae

κ Aquilae
Location of κ Aquilae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 19h 36m 53.44952s[1]
Declination –7° 01′ 38.9176″[1]
Apparent magnitude (V) +4.957[2]
Characteristics
Spectral type B0.5 III[3]
U−B color index –0.861[2]
B−V color index –0.028[2]
Astrometry
Radial velocity (Rv)–19.4[4] km/s
Proper motion (μ) RA: +1.63[1] mas/yr
Dec.: –2.65[1] mas/yr
Parallax (π)1.94 ± 0.20 mas[1]
Distanceapprox. 1,700 ly
(approx. 520 pc)
Absolute magnitude (MV)−3.60[5]
Details
Mass15.50 ± 0.61[6] M☉
Radius12.5[7] R☉
Luminosity52,630[6] L☉
Surface gravity (log g)3.5[8] cgs
Temperature26,500[6] K
Metallicity [Fe/H]−0.16[5] dex
Rotational velocity (v sin i)265[9] km/s
Age11.1 ± 0.5[3] Myr
Other designations
κ Aql, 39 Aquilae, BD–07 5006, FK5 737, HD 184915, HIP 96483, HR 7446, SAO 143600.[10]
Database references
SIMBADdata

Kappa Aquilae, Latinized from κ Aquilae, is the Bayer designation for a star in the equatorial constellation of Aquila. It is a faint star at apparent visual magnitude +4.957,[2] but bright enough to be seen with the naked eye in dark suburban skies. The annual parallax is only 1.94 mas,[1] which equates to a distance of approximately 1,700 light-years (520 parsecs) from Earth (with a 10% margin of error).

The spectrum of Kappa Aquilae matches a stellar classification of B0.5 III,[3] where the luminosity class of III is typically associated with evolved giant stars. This is a star with 15.50[6] times the Sun's mass and 12.5[7] times the radius of the Sun. Massive stars like this blaze brightly; it is radiating 52,630-fold[6] the Sun's luminosity from its outer atmosphere with an effective temperature of 26,500 K,[6] giving it the intense blue-white glow of a B-type star. It is only 11 million years of age[3] and is spinning rapidly with a projected rotational velocity of 265 km/s.[9]

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