20 Aquilae, abbreviated 20 Aql, is an irregular variable[11] star in the equatorial constellation of Aquila. 20 Aquilae is its Flamsteed designation. It ranges in magnitude from a peak of 5.33 down to 5.36, which is bright enough for the star to be visible to the naked eye.[12] The estimated distance to this star is around 920 light years, based upon an annual parallax shift of 3.5 mas.[2] The star is moving closer to the Earth with a heliocentric radial velocity of −23 km/s.[7]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Aquila |
Right ascension | 19h 12m 40.71201s[2] |
Declination | −07° 56′ 22.2650″[2] |
Apparent magnitude (V) | 5.362[3] |
Characteristics | |
Spectral type | B3 V,[4] B3 IV,[5] or B2/3 II[6] |
B−V color index | +0.088[3] |
Astrometry | |
Radial velocity (Rv) | −23.0±0.7[7] km/s |
Proper motion (μ) | RA: +14.040[2] mas/yr Dec.: –6.814[2] mas/yr |
Parallax (π) | 3.5374 ± 0.1720 mas[2] |
Distance | 920 ± 40 ly (280 ± 10 pc) |
Absolute magnitude (MV) | −2.02[8] |
Details | |
Mass | 8.6±0.2[9] M☉ |
Luminosity (bolometric) | 7,284[3] L☉ |
Temperature | 18,700[3] K |
Rotational velocity (v sin i) | 133±6[4] km/s |
Age | 27.9±4.1[9] Myr |
Other designations | |
Database references | |
SIMBAD | data |
There has been some disagreement over the stellar classification of this star. Buscombe (1962) listed a class of B3 IV,[5] which suggests a B-type subgiant star that has exhausted the hydrogen at its core and is expanding off the main sequence. Lesh (1968)[13] and Braganca et al. (2012)[4] matched a B-type main sequence star with a class of B3 V. However, Houk and Swift (1999) found a class of B2/3 II,[6] indicating this is an evolved bright giant.
The star is about 28[9] million years old with a high rate of spin, showing a projected rotational velocity of 133 km/s.[4] It has 8.6[9] times the mass of the Sun and is radiating 7,284 times the Sun's luminosity from its photosphere at an effective temperature of 18,700 K.[3]