20 Aquilae

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20 Aquilae
20AqlLightCurve.png
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

  1. ↑ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
  2. 1 2 3 4 5 6 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 .
  3. 1 2 3 4 5 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.
  4. 1 2 3 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.
  5. 1 2 Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM...4....1B.
  6. 1 2 Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
  7. 1 2 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.
  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.
  9. 1 2 3 4 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.
  10. ↑ "20 Aql". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved October 29, 2018.
  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.
  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.
  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 .
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