27 Aquilae (abbreviated 27 Aql) is a star in the equatorial constellation of Aquila. 27 Aquilae is its Flamsteed designation though it also bears the Bayer designation d Aquilae. It has an apparent visual magnitude of 5.49,[2] which is faintly visible to the naked eye. Based upon parallax measurements made during the Hipparcos mission, this star is at a distance of 440 light-years (130 parsecs) from Earth, give or take a 20 light-year margin of error.[1] At this distance, the brightness of the star is diminished from extinction caused by interstellar gas and dust.[5]

27 Aquilae

Location of 27 Aquilae (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Aquila
Right ascension	19h 20m 35.68321s[1]
Declination	−00° 53′ 31.8067″[1]
Apparent magnitude (V)	5.49[2]
Characteristics
Spectral type	B9 III[3]
U−B color index	−0.23[2]
B−V color index	−0.04[2]
Astrometry
Radial velocity (Rv)	−27[4] km/s
Proper motion (μ)	RA: 5.42[1] mas/yr Dec.: 2.83[1] mas/yr
Parallax (π)	7.45 ± 0.28 mas[1]
Distance	440 ± 20 ly (134 ± 5 pc)
Absolute bolometric magnitude (Mbol)	2.04–2.27[5]
Details
Surface gravity (log g)	3.61 ± 0.50[6] cgs
Temperature	11,500[6] K
Rotational velocity (v sin i)	55[7] km/s
Other designations
BD−01° 3716, GC 26673, HD 181440, HIP 95073, HR 7336, PPM 180629, SAO 143292.[8]
Database references
SIMBAD	data

The spectrum of 27 Aquilae fits a stellar classification of B9 III,[3] with the luminosity class of III typically indicating this is an evolved giant star. As it lies within the field of view of the CoRoT satellite,[6] close observation have been made of its luminosity. The star shows a multiperiodic variability with at least six pulsation frequencies discovered.[9] It has a high rate of rotation with a projected rotational velocity of 55 km/s.[7] The outer atmosphere is radiating energy into space at an effective temperature of around 11,500 K,[6] giving it the blue-white hue of a B-type star.

References