28 Aquilae

28 Aquilae, abbreviated 28 Aql, is a star in the equatorial constellation of Aquila. 28 Aquilae is its Flamsteed designation though it also bears the Bayer designation A Aquilae. It has an apparent visual magnitude is 5.5,[2] making this a faint star that requires dark suburban skies to view (according to the Bortle Dark-Sky Scale). The annual parallax shift of 9.67 mas[1] means this star is located at a distance of approximately 340 light-years (100 parsecs) from Earth.

28 Aquilae
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension  19h 19m 39.34830s[1]
Declination +12° 22′ 28.8398″[1]
Apparent magnitude (V) 5.531[2]
Characteristics
Spectral type F0 III[2]
U−B color index +0.182[3]
B−V color index +0.257[3]
Variable type δ Sct[4]
Astrometry
Radial velocity (Rv)+4.36[2] km/s
Proper motion (μ) RA: +3.974[1] mas/yr
Dec.: +16.589[1] mas/yr
Parallax (π)9.6330 ± 0.1361[5] mas
Distance339 ± 5 ly
(104 ± 1 pc)
Absolute magnitude (MV)+0.46[6]
Details
Luminosity54.20[6] L☉
Surface gravity (log g)3.41[7] cgs
Temperature7,250[2] K
Metallicity [Fe/H]–0.16[2] dex
Rotational velocity (v sin i)57[8] km/s
Other designations
28 Aql, V1208 Aql, BD+12° 3879, HD 181333, HIP 94982, HR 7331, SAO 104722[9]
Database references
SIMBADdata

The spectrum of this star matches a stellar classification of F0 III,[2] with the luminosity class of III indicating this is most likely an evolved giant star. The variability of this star was discovered by Michel Breger in 1969. It was revealed to be a Delta Scuti-type pulsating variable star with at least two periods of pulsation. The known periods have frequencies of 6.68 and 7.12 cycles per day.[4] The outer atmosphere has an effective temperature of 7,250 K,[2] which lies in the range of a yellow-white hued F-type star.[10]

References
  1. 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. Luck, R. Earle; Heiter, Ulrike (June 2007), "Giants in the Local Region", The Astronomical Journal, 133 (6): 2464–2486, Bibcode:2007AJ....133.2464L, doi:10.1086/513194.
  3. Breger, M. (March 1968), "UBV and narrow-band UVBY photometry of bright stars", Astronomical Journal, 73: 84–85, Bibcode:1968AJ.....73...84B, doi:10.1086/110602.
  4. Dall, T. H.; Frandsen, S. (May 2002), "Mode characterisation in delta Scuti stars. I. rho Pup, GN And, V1208 Aql and AV Cet", Astronomy and Astrophysics, 386: 964–970, Bibcode:2002A&A...386..964D, doi:10.1051/0004-6361:20020357.
  5. 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.
  6. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  7. Soubiran, C.; et al. (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.
  8. Royer, F.; et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897–911, arXiv:astro-ph/0205255, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943.
  9. "* 28 Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-22.
  10. "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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