Rho2 Cephei

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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]
Spectral type A3 V[3]
U−B color index +0.07[2]
B−V color index +0.06[2]
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]
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

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.

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.


  1. 1.0 1.1 1.2 1.3 1.4 1.5 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.
  2. 2.0 2.1 2.2 2.3 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. 3.0 3.1 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. 4.0 4.1 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.
  5. 5.0 5.1 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.
  6. 6.0 6.1 Gullikson, Kevin; Kraus, Adam; Dodson-Robinson, Sarah (2016). "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars". The Astronomical Journal 152 (2): 40. Bibcode 2016AJ....152...40G.
  7. 7.0 7.1 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.
  8. "rho Cep -- Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=rho02+Cep, 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.