Kappa Aquilae
# Kappa Aquilae

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, but bright enough to be seen with the naked eye in dark suburban skies. The annual parallax is only 1.94 mas, 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, where the luminosity class of III is typically associated with evolved giant stars. This is a star with 15.50 times the Sun's mass and 12.5 times the radius of the Sun. Massive stars like this blaze brightly; it is radiating 52,630-fold the Sun's luminosity from its outer atmosphere with an effective temperature of 26,500 K, giving it the intense blue-white glow of a B-type star. It is only 11 million years of age and is spinning rapidly with a projected rotational velocity of 265 km/s.

## Etymology

In Chinese, 右旗 (Yòu Qí), meaning Right Flag, refers to an asterism consisting of κ Aquilae, μ Aquilae, σ Aquilae, δ Aquilae, ν Aquilae, 42 Aquilae, ι Aquilae, HD 184701 and 56 Aquilae. Consequently, the Chinese name for κ Aquilae itself is 右旗八 (Yòu Qí bā, English: the Eighth Star of Right Flag.)

This star, together with η Aql, θ Aql, δ Aql, ι Aql and λ Aql were once part of the now-obsolete constellation Antinous.

