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]
Distance434 ± 3 ly
(133.1 ± 0.8 pc)
Absolute magnitude (MV)+0.64[4]
Details
Mass2.2[4] M☉
Radius11.17+0.32
−0.70[1] R☉
Luminosity56.397±0.468[1] L☉
Surface gravity (log g)2.48[5] cgs
Temperature4,733+155
−67[1] K
Metallicity [Fe/H]−0.19±0.06[5] dex
Age0.5[4] Gyr
Other designations
BD+00 4170, HD 181053, HIP 94913, HR 7321, SAO 124492[6]
Database references
SIMBADdata

This is a so-called 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]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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 (3): 667–679, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
  3. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  4. 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, S2CID 5863942.
  5. 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, S2CID 118362423.
  6. "* 24 Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-25.{{cite web}}: CS1 maint: postscript (link)
  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 18, 2012, retrieved 2012-01-16
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