28 Aquilae

This article is about A Aquilae. It is not to be confused with Alpha Aquilae, also known as Altair.

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, and the variable star designation V1208 Aquilae. It has an apparent visual magnitude is 5.5,^[4] making this a faint star that requires dark suburban skies to view (according to the Bortle Dark-Sky Scale). The annual parallax shift of 9.6 mas means this star is located at a distance of approximately 340 light-years (100 parsecs) from Earth.

28 Aquilae

A light curve for V1208 Aquilae, plotted from Hipparcos data[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Aquila
Right ascension	19h 19m 39.34802s[2]
Declination	+12° 22′ 28.8457″[2]
Apparent magnitude (V)	5.51 - 5.56[3]
Characteristics
Spectral type	F0 III[4]
U−B color index	+0.182[5]
B−V color index	+0.257[5]
Variable type	δ Sct[3]
Astrometry
Radial velocity (Rv)	+4.36[4] km/s
Proper motion (μ)	RA: +4.249[2] mas/yr Dec.: +16.199[2] mas/yr
Parallax (π)	9.5836 ± 0.0768 mas[2]
Distance	340 ± 3 ly (104.3 ± 0.8 pc)
Absolute magnitude (MV)	+0.46[6]
Details
Mass	2.4[2] M☉
Radius	4.8[2] R☉
Luminosity	54.20[6] L☉
Surface gravity (log g)	3.41[7] cgs
Temperature	7,250[4] K
Metallicity [Fe/H]	−0.16[4] dex
Rotational velocity (v sin i)	57[8] km/s
Age	655[2] Myr
Other designations
28 Aql, V1208 Aql, BD+12°3879, HD 181333, HIP 94982, HR 7331, SAO 104722[9]
Database references
SIMBAD	data

The spectrum of this star matches a stellar classification of F0 III.^[4] Despite consistent spectral classifications as a giant star,^[10] models show that it is just reaching the end of its main sequence lifetime at an age of 655 million years.^[2]

The variability of 28 Aquilae 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.^[11] The outer atmosphere has an effective temperature of 7,250 K,^[4] which lies in the range of a yellow-white hued F-type star.^[12]

References

1. "Light Curve", Hipparcos ESA, ESA, retrieved 17 February 2022.
2. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
3. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
4. 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.
5. 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.
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, S2CID 119257644.
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, S2CID 118362423.
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, S2CID 14070763.
9. "* 28 Aql", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2012-07-22.
10. Skiff, B. A. (2014), "VizieR Online Data Catalog: Catalogue of Stellar Spectral Classifications (Skiff, 2009–2016)", VizieR On-line Data Catalog, Bibcode:2014yCat....1.2023S.
11. 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 (3): 964–970, Bibcode:2002A&A...386..964D, doi:10.1051/0004-6361:20020357.
12. "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.

External links

• HR 7331
• CCDM 19197+1222
• 28 Aquilae^{[permanent dead link‍]}