7 Cephei

7 Cephei is a single[10] star located approximately 820 light years away, in the northern circumpolar constellation of Cepheus. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.42.[2]

7 Cephei
Observation data
Epoch J2000      Equinox J2000
Constellation Cepheus
Right ascension 21h 27m 46.14144s[1]
Declination +66° 48′ 32.7406″[1]
Apparent magnitude (V) 5.42[2]
Characteristics
Evolutionary stage main sequence[3]
Spectral type B7 V[4]
B−V color index −0.099±0.004[2]
Astrometry
Radial velocity (Rv)+3.0±4.2[5] km/s
Proper motion (μ) RA: −11.296[1] mas/yr
Dec.: −19.787[1] mas/yr
Parallax (π)3.9653 ± 0.1148 mas[1]
Distance820 ± 20 ly
(252 ± 7 pc)
Absolute magnitude (MV)−1.54[2]
Details
Mass4.47±0.07[3] M☉
Radius3.0[6] R☉
Luminosity769+94
−84[3] L☉
Surface gravity (log g)3.56[7] cgs
Temperature12,560+87
−86[3] K
Metallicity [Fe/H]−0.36[7] dex
Rotational velocity (v sin i)236[3] km/s
Age38[8] Myr
Other designations
7 Cep, BD+66°1405, FK5 3718, HD 204770, HIP 105972, HR 8227, SAO 19432[9]
Database references
SIMBADdata

This is a B-type main-sequence star with a stellar classification of B7 V.[4] It is a candidate variable star with an amplitude of 9 micromagnitudes and a period of 0.737±0.002 d.[11] This object has 4.5[3] times the mass of the Sun and about three[6] times the Sun's radius. It is spinning rapidly with a projected rotational velocity of 236 km/s.[3] 7 Cephei is radiating 769[3] times the luminosity of the Sun from its photosphere at an effective temperature of 12,560 K.[3]

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. 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.
  3. Zorec, J.; et al. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy and Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
  4. 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
  5. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 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.
  6. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (Third ed.), 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
  7. Niemczura, E. (June 2003), "Metallicities of the SPB stars from the IUE ultraviolet spectra", Astronomy and Astrophysics, 404 (2): 689–700, Bibcode:2003A&A...404..689N, doi:10.1051/0004-6361:20030546
  8. Gullikson, Kevin; et al. (2016), "The Close Companion Mass-Ratio Distribution of Intermediate-Mass Stars", The Astronomical Journal, 152 (2): 40, arXiv:1604.06456, Bibcode:2016AJ....152...40G, doi:10.3847/0004-6256/152/2/40, S2CID 119179065.
  9. "7 Cep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved April 25, 2019.
  10. 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.
  11. Burggraaff, O.; et al. (September 2018), "Studying bright variable stars with the Multi-site All-Sky CAmeRA (MASCARA)", Astronomy & Astrophysics, 617: 11, arXiv:1806.02247, Bibcode:2018A&A...617A..32B, doi:10.1051/0004-6361/201833142, S2CID 84836583, A32.
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