 A light curve for 20 Aquilae, plotted from Hipparcos data | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 19 12 40.71201 |
| Declination | −07° 56′ 22.2650″ |
| Apparent magnitude (V) | 5.362 |
| Characteristics | |
| Spectral type | B3 V, B3 IV, or B2/3 II |
| B−V color index | +0.088 |
| Astrometry | |
| Radial velocity (Rv) | −23.0±0.7 km/s |
| Proper motion (μ) | RA: +14.040 mas/yr Dec.: –6.814 mas/yr |
| Parallax (π) | 3.5374 ± 0.1720 mas |
| Distance | 920 ± 40 ly (280 ± 10 pc) |
| Absolute magnitude (MV) | −2.02 |
| Details | |
| Mass | 8.6±0.2 M☉ |
| Luminosity (bolometric) | 7,284 L☉ |
| Temperature | 18,700 K |
| Rotational velocity (v sin i) | 133±6 km/s |
| Age | 27.9±4.1 Myr |
| Other designations | |
| 20 Aql, NSV 11808, BD−08° 4887, GC 26461, HD 179406, HIP 94385, HR 7279, SAO 143134 | |
| Database references | |
| SIMBAD | data |
20 Aquilae, abbreviated 20 Aql, is an irregular variable 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. The estimated distance to this star is around 920 light years, based upon an annual parallax shift of 3.5 mas. The star is moving closer to the Earth with a heliocentric radial velocity of −23 km/s.
There has been some disagreement over the stellar classification of this star. Buscombe (1962) listed a class of B3 IV, which suggests a B-type subgiant star that has exhausted the hydrogen at its core and is expanding off the main sequence. Lesh (1968) and Braganca et al. (2012) 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, indicating this is an evolved bright giant.
The star is about 28 million years old with a high rate of spin, showing a projected rotational velocity of 133 km/s. It has 8.6 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.
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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