Rho2 Cephei

Rho2 Cephei, Latinized from ρ2 Cephei, or simply ρ Cephei, is a solitary[9] star in the northern constellation of Cepheus. With an apparent visual magnitude of 5.50,[2] it is faintly visible to the naked eye, forming an optical pair with Rho1 Cephei. Based upon an annual parallax shift of 13.31 mas as seen from the Earth,[1] it is located about 245 light years from the Sun.

For other stars with this Bayer designation, see ρ Cephei.
Rho2 Cephei
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cepheus
Right ascension 22h 29m 52.97918s[1]
Declination +78° 49′ 27.4282″[1]
Apparent magnitude (V) 5.50[2]
Characteristics
Spectral type A3 V[3]
U−B color index +0.07[2]
B−V color index +0.06[2]
Astrometry
Proper motion (μ) RA: +3.68[1] mas/yr
Dec.: −21.29[1] mas/yr
Parallax (π)13.31 ± 0.21[1] mas
Distance245 ± 4 ly
(75 ± 1 pc)
Absolute magnitude (MV)+1.07[4]
Details
Mass2.23±0.03[5] M☉
Luminosity32[4] L☉
Surface gravity (log g)4.2[6] cgs
Temperature8,511[5] K
Rotational velocity (v sin i)133[7] km/s
Age85[6] Myr
Other designations
 Cephei, ρ2 Cep, 29 Cephei, BD+78° 801, FK5 1593, HD 213798, HIP 111056, HR 8591, SAO 10402[8]
Database references
SIMBADdata

Rho2 Cephei is an A-type main sequence star with a stellar classification of A3 V,[3] estimated to be 85 million years old. It has a high rate of rotation, showing a projected rotational velocity of 133 km/s.[7] The effective temperature of its photosphere is 8,511 K and its bolometric luminosity, the total amount of radiation it emits at all wavelengths, is 32 L☉.

References
  1. van Leeuwen, F. (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.
  2. Oja, T. (April 1983), "UBV photometry of FK4 and FK4 supplement stars", Astronomy and Astrophysics Supplement Series, 52: 131–134, Bibcode:1983A&AS...52..131O.
  3. Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
  4. 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.
  5. Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
  6. Gullikson, Kevin; Kraus, Adam; Dodson-Robinson, Sarah (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.
  7. Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298.
  8. "rho Cep -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-05-05.
  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.
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