24 Aquilae

24 Aquilae (abbreviated 24 Aql) is a star in the equatorial constellation of Aquila. 24 Aquilae is its Flamsteed designation. It is located at a distance of around 434 light-years (133 parsecs)^[1] from Earth and has an apparent visual magnitude of 6.4.^[2] According to the Bortle Dark-Sky Scale, this star is just visible to the naked eye in dark rural skies. It is drifting closer to the Sun with a radial velocity of −26 km/s.^[1]

24 Aquilae

Observation data Epoch J2000      Equinox J2000
Constellation	Aquila
Right ascension	19h 18m 50.94777s[1]
Declination	+00° 20′ 20.5448″[1]
Apparent magnitude (V)	6.423[2]
Characteristics
Spectral type	K0-IIIa:CH1Ba0.5[3]
U−B color index	+0.770[2]
B−V color index	+1.050[2]
Astrometry
Radial velocity (Rv)	−26.13±0.15[1] km/s
Proper motion (μ)	RA: +10.755[1] mas/yr Dec.: +11.298[1] mas/yr
Parallax (π)	7.5115±0.0437 mas[1]
Distance	434 ± 3 ly (133.1 ± 0.8 pc)
Absolute magnitude (MV)	+0.64[4]
Details
Mass	2.2[4] M☉
Radius	11.17+0.32 −0.70[1] R☉
Luminosity	56.397±0.468[1] L☉
Surface gravity (log g)	2.48[5] cgs
Temperature	4,733+155 −67[1] K
Metallicity [Fe/H]	−0.19±0.06[5] dex
Age	0.5[4] Gyr
Other designations
BD+00 4170, HD 181053, HIP 94913, HR 7321, SAO 124492[6]
Database references
SIMBAD	data

This is a mild barium star, as identified by the presence of a weak absorption line of singly-ionized barium atoms at a wavelength of 455.4 nm. Such stars display an atmospheric overabundance of carbon and the heavy elements produced by the s-process, which was most likely transferred into the atmosphere by a wide binary stellar companion. However, in the case of 24 Aquilae, the abundances of heavy elements are near normal.^[4]

At an estimated age of a half billion years,^[4] 24 Aquilae is a evolved giant star with a stellar classification of K0 IIIa.^[4] It has more than double the mass of the Sun, 11 times the Sun's radius, and shines with 56 times the Sun's luminosity.^[1] It is radiating this energy into space from its outer atmosphere at an effective temperature of 4,733 K.^[1] This heat is what gives it the cool orange hue characteristic of a K-type star.^[7]