28 Vulpeculae

28 Vulpeculae is a single[9] star in the northern constellation of Vulpecula. It lies approximately 560 light years away and is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 5.047.[2] The star is moving closer to the Sun with a heliocentric radial velocity of −23 km/s, and may come as close as 198 light-years in 5.9 million years.[5]

28 Vulpeculae
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Vulpecula
Right ascension 20h 38m 31.9139s[1]
Declination +24° 06′ 57.4433″[1]
Apparent magnitude (V) 5.05[2]
Characteristics
Evolutionary stage Subgiant
Spectral type B5IV[3]
U−B color index −0.53[4]
B−V color index −0.14[4]
Astrometry
Radial velocity (Rv)−22.6±1.2[5] km/s
Proper motion (μ) RA: 10.317±0.273[1] mas/yr
Dec.: −6.940±0.253[1] mas/yr
Parallax (π)5.8740 ± 0.1760 mas[1]
Distance560 ± 20 ly
(170 ± 5 pc)
Absolute magnitude (MV)−0.96[5]
Details
Mass5.0[2] M☉
Luminosity713[2] L☉
Surface gravity (log g)3.77[6] cgs
Temperature15,200[2] K
Metallicity [Fe/H]+0.02±0.04[6] dex
Rotational velocity (v sin i)285[7] km/s
Other designations
28 Vul, BD+23°4084, HD 196740, HIP 101868, HR 7894, SAO 88945[8]
Database references
SIMBADdata

This is a subgiant star with a spectral class of B5 IV,[3] indicating a hot massive star that has started to evolve away from the main sequence after exhausting it core hydrogen. It has been included in a list of the least variable stars observed with the Hipparcos satellite; its brightness varied by no more than 0.0005 magnitudes in the Hipparcos passband.[10] The star has five[2] times the mass of the Sun and is spinning rapidly with a projected rotational velocity of 285 km/s.[7] It is radiating 713 times the Sun's luminosity from its photosphere at an effective temperature of 15,200 K.[2]

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. Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (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.
  3. Lesh, Janet Rountree (1968). "The Kinematics of the Gould Belt: An Expanding Group?". The Astrophysical Journal Supplement Series. 17: 371. Bibcode:1968ApJS...17..371L. doi:10.1086/190179.
  4. Hoffleit, Dorrit; Jaschek, Carlos (1991). "The Bright star catalogue". New Haven, Conn.: Yale University Observatory, 5th Rev.ed. Bibcode:1991bsc..book.....H.
  5. 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.
  6. Wu, Yue; Singh, H. P.; Prugniel, P.; Gupta, R.; Koleva, M. (2011). "Coudé-feed stellar spectral library - atmospheric parameters". Astronomy and Astrophysics. 525: A71. arXiv:1009.1491. Bibcode:2011A&A...525A..71W. doi:10.1051/0004-6361/201015014. S2CID 53480665.
  7. Abt, Helmut A.; Levato, Hugo; Grosso, Monica (2002). "Rotational Velocities of B Stars". The Astrophysical Journal. 573 (1): 359. Bibcode:2002ApJ...573..359A. doi:10.1086/340590.
  8. "28 Vulpeculae". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-11-17.
  9. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  10. Adelman, S. J. (2001). "Research Note Hipparcos photometry: The least variable stars". Astronomy and Astrophysics. 367: 297–298. Bibcode:2001A&A...367..297A. doi:10.1051/0004-6361:20000567.
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