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]
References
edit- ^ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
- ^ a b c d e f 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.
- ^ a b c d e 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.
- ^ a b c d 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.
- ^ a b Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM...4....1B.
- ^ a b Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
- ^ a b 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.
- ^ a b c d 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.