28 Aquilae

This article is about A Aquilae. It is not to be confused with Alpha Aquilae, also known as Altair.
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]
Distance340 ± 3 ly
(104.3 ± 0.8 pc)
Absolute magnitude (MV)+0.46[6]
Details
Mass2.4[2] M☉
Radius4.8[2] R☉
Luminosity54.20[6] L☉
Surface gravity (log g)3.41[7] cgs
Temperature7,250[4] K
Metallicity [Fe/H]−0.16[4] dex
Rotational velocity (v sin i)57[8] km/s
Age655[2] Myr
Other designations
28 Aql, V1208 Aql, BD+12°3879, HD 181333, HIP 94982, HR 7331, SAO 104722[9]
Database references
SIMBADdata

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.

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]

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