21 Aquilae

21 Aquilae is a solitary[9] variable star in the equatorial constellation of Aquila. It has the variable star designation V1288 Aql; 21 Aquilae is its Flamsteed designation. This object is visible to the naked eye as a dim, blue-white hued star with a baseline apparent visual magnitude of 5.14.[2] The star is located at a distance of around 740 light-years (230 parsecs) from Earth, give or take a 30 light-year margin of error.[10] It is moving closer to the Earth with a heliocentric radial velocity of –5 km/s.[5]

21 Aquilae
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 19h 13m 42.70079s[1]
Declination +02° 17′ 37.2921″[1]
Apparent magnitude (V) 5.140[2]
Characteristics
Spectral type B8 II-III[3]
U−B color index –0.399[2]
B−V color index –0.065[2]
Variable type α2 CVn[4]
Astrometry
Radial velocity (Rv)–5.2[5] km/s
Proper motion (μ) RA: +10.537[1] mas/yr
Dec.: +0.375[1] mas/yr
Parallax (π)4.3902 ± 0.1945[1] mas
Distance740 ± 30 ly
(230 ± 10 pc)
Absolute magnitude (MV)−2.12[6]
Details
Radius4.3[7] R☉
Luminosity913.05[6] L☉
Surface gravity (log g)3.27[3] cgs
Temperature13,175[3] K
Metallicity [Fe/H]–0.14[3] dex
Other designations
21 Aql, V1288 Aql, BD+02°3824, FK5 3537, HD 179761, HIP 94477, HR 7287, SAO 124408, WDS J19137+0218A[8]
Database references
SIMBADdata

The stellar classification of this star is B8 II-III,[3] with the luminosity class of II-III suggesting that the spectrum displays elements of both a giant star and a bright giant. It is a chemically peculiar star of the Mercury-Manganese type (CP3).[11] This is a probable Alpha2 Canum Venaticorum variable that ranges in visual magnitude from 5.06 down to 5.16.[4] The star is radiating 913[6] times the luminosity of the Sun from its photosphere at an effective temperature of 13,175 K;[3] this searing heat gives it the blue-white glow of a B-type star.[12]

21 Aquilae is catalogued as an optical double star, having a 12th magnitude companion 37″ away as of 2010. It was first identified as a double star by John Herschel.[13] The companion is a distant background object.[14]

References
  1. 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. Gaia DR2 record for this source at VizieR.
  2. Stepien, K. (December 1968), "Photometric behavior of magnetic stars", Astrophysical Journal, 154: 945, Bibcode:1968ApJ...154..945S, doi:10.1086/149815.
  3. Cenarro, A. J.; et al. (January 2007), "Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters", Monthly Notices of the Royal Astronomical Society, 374 (2): 664–690, arXiv:astro-ph/0611618, Bibcode:2007MNRAS.374..664C, doi:10.1111/j.1365-2966.2006.11196.x, S2CID 119428437.
  4. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  5. Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, 30, University of Toronto: International Astronomical Union, p. 57, Bibcode:1967IAUS...30...57E.
  6. 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.
  7. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
  8. "21 Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-05.
  9. Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  10. van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  11. Ghazaryan, S.; et al. (November 2018), "New catalogue of chemically peculiar stars, and statistical analysis", Monthly Notices of the Royal Astronomical Society, 480 (3): 2953–2962, arXiv:1807.06902, Bibcode:2018MNRAS.480.2953G, doi:10.1093/mnras/sty1912, S2CID 119062018.
  12. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 10, 2012, retrieved 2012-01-16
  13. Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. Retrieved 2015-07-22.
  14. 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. Gaia DR2 record for this source at VizieR.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.