24 Aquilae

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24 Aquilae
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension  19h 18m 50.94332s[1]
Declination 00° 20′ 20.4817″[1]
Apparent magnitude (V) 6.423[2]
Spectral type K0 IIIa[3]
U−B color index +0.770[2]
B−V color index +1.050[2]
Radial velocity (Rv)-28.5[4] km/s
Proper motion (μ) RA: +15.96[1] mas/yr
Dec.: +8.77[1] mas/yr
Parallax (π)7.87 ± 0.49[1] mas
Distance410 ± 30 ly
(127 ± 8 pc)
Absolute magnitude (MV)+0.64[3]
Mass2.2[3] M
Luminosity63[3] L
Surface gravity (log g)2.48[5] cgs
Temperature4,810[5] K
Metallicity [Fe/H]–0.19 ± 0.06[5] dex
Age0.5[3] Gyr
Other designations
BD+00 4170, HD 181053, HIP 94913, HR 7321, SAO 124492.[6]
Database references

24 Aquilae (abbreviated 24 Aql) is a star in the equatorial constellation of Aquila. 24 Aquilae is its Flamsteed designation. It is at a distance of around 410 light-years (130 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.

This is a so-called mild barium star, as identified by the mild presence of an 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.[3]

At an estimated age of a half billion years,[3] 24 Aquilae is a giant star with a stellar classification of K0 IIIa,[3] it has more than double the mass of the Sun and shines with 63[3] times the Sun's luminosity. It is radiating this energy into space from its outer atmosphere at an effective temperature of 4,810 K;[5] this heat is what gives it the cool orange hue characteristic of a K-type star.[7]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ^ a b c d Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants", Monthly Notices of the Royal Astronomical Society, 172: 667–679, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
  3. ^ a b c d e f g h i Smiljanic, R.; Porto de Mello, G. F.; da Silva, L. (June 2007), "Abundance analysis of barium and mild barium stars", Astronomy and Astrophysics, 468 (2): 679–693, arXiv:astro-ph/0702421, Bibcode:2007A&A...468..679S, doi:10.1051/0004-6361:20065867.
  4. ^ Wilson, Ralph Elmer (1953), General Catalogue of Stellar Radial Velocities, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W.
  5. ^ a b c d Soubiran, C.; Le Campion, J.-F.; Cayrel de Strobel, G.; Caillo, A. (June 2010), "The PASTEL catalogue of stellar parameters", Astronomy and Astrophysics, 515: A111, arXiv:1004.1069, Bibcode:2010A&A...515A.111S, doi:10.1051/0004-6361/201014247.
  6. ^ "* 24 Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-25.
  7. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 10, 2012, retrieved 2012-01-16

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