20 Aquilae

20 Aquilae
	; A light curve for 20 Aquilae, plotted from Hipparcos data[1]
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
	20 Aql, NSV 11808, BD−08° 4887, GC 26461, HD 179406, HIP 94385, HR 7279, SAO 143134[10]
Database references
SIMBAD	data

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]

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]

References

"Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
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.
Hohle, M. M.; et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355, S2CID 111387483.
Bragança, G. A.; et al. (November 2012), "Projected Rotational Velocities and Stellar Characterization of 350 B Stars in the Nearby Galactic Disk", The Astronomical Journal, 144 (5): 10, arXiv:1208.1674, Bibcode:2012AJ....144..130B, doi:10.1088/0004-6256/144/5/130, S2CID 118868235, 130.
Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM...4....1B.
Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
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.
Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873.
"20 Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 29, 2018.
Lefèvre, L.; Marchenko, S. V.; Moffat, A. F. J.; Acker, A. (2009), "A systematic study of variability among OB-stars based on HIPPARCOS photometry", Astronomy and Astrophysics, 507 (2): 1141–1201, Bibcode:2009A&A...507.1141L, doi:10.1051/0004-6361/200912304, ISSN 0004-6361.
Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
Lesh, Janet Rountree (December 1968), "The Kinematics of the Gould Belt: an Expanding Group?", Astrophysical Journal Supplement, 17: 371, Bibcode:1968ApJS...17..371L, doi:10.1086/190179.

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[HipDataAccess-1] "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.

[GaiaDR2-2] 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.

[Hohle2010-3] Hohle, M. M.; et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355, S2CID 111387483.

[Braganca2012-4] Bragança, G. A.; et al. (November 2012), "Projected Rotational Velocities and Stellar Characterization of 350 B Stars in the Nearby Galactic Disk", The Astronomical Journal, 144 (5): 10, arXiv:1208.1674, Bibcode:2012AJ....144..130B, doi:10.1088/0004-6256/144/5/130, S2CID 118868235, 130.

[Buscombe1962-5] Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM...4....1B.

[Houk1999-6] Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.

[Gontcharov2006-7] Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.

[Anderson2012-8] 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.

[Tetzlaff2011-9] Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873.

[SIMBAD-10] "20 Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 29, 2018.

[lefevre2009-11] Lefèvre, L.; Marchenko, S. V.; Moffat, A. F. J.; Acker, A. (2009), "A systematic study of variability among OB-stars based on HIPPARCOS photometry", Astronomy and Astrophysics, 507 (2): 1141–1201, Bibcode:2009A&A...507.1141L, doi:10.1051/0004-6361/200912304, ISSN 0004-6361.

[Samus2017-12] Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.

[Lesh1968-13] Lesh, Janet Rountree (December 1968), "The Kinematics of the Gould Belt: an Expanding Group?", Astrophysical Journal Supplement, 17: 371, Bibcode:1968ApJS...17..371L, doi:10.1086/190179.