Omicron Cephei

ο Cephei
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cepheus
ο Cep A
Right ascension 23h 18m 37.493s
Declination +68° -6′ 41.20″[1]
Apparent magnitude (V) 4.86[2]
ο Cep B
Right ascension 23h 18m 37.115s
Declination +68° 06′ 38.65″[3]
Apparent magnitude (V) 7.13[2]
Characteristics
U−B color index +0.49[2]
B−V color index +0.84[2]
R−I color index +0.45[2]
ο Cep A
Spectral type G8III[4]
ο Cep B
Spectral type F6V[2]
Astrometry
ο Cep A
Proper motion (μ) RA: 54.88[1] mas/yr
Dec.: 10.91[1] mas/yr
Parallax (π)15.48 ± 0.55 mas[5]
Distance211 ± 7 ly
(65 ± 2 pc)
Absolute magnitude (MV)0.78[6]
ο Cep B
Proper motion (μ) RA: 45.70[3] mas/yr
Dec.: 13.19[3] mas/yr
Orbit[4]
Period (P)1505±40 y
Semi-major axis (a)3.13±0.12 ″
Eccentricity (e)0.439±0.020
Inclination (i)16.0±4.0°
Longitude of the node (Ω)4.5±4.5°
Periastron epoch (T)B1692 ± 20
Argument of periastron (ω)
(secondary)		93.0±20.0°
Details
ο Cep A
Mass2.35 ± 0.15[4] M☉
Luminosity51[6] L☉
Metallicity [Fe/H]0.05±0.02[6] dex
ο Cep B
Mass1.29[4] M☉
Other designations
ο Cep, Omicron Cephei, Omicron Cep, 34 Cephei, 34 Cep, STF 3001AB, ADS 16666 AB, BD+67°1514, CCDM J23186+6807AB, GC 32463, GSC 04478-01361, HD 219916, HIP 115088, HR 8872, IDS 23145+6734 AB, PPM 24360, SAO 20554, WDS 23186+6807AB.[5][7]
Database references
SIMBADdata

Omicron Cephei, Latinized from ο Cephei, is a binary star in the constellation of Cepheus.[5] It consists of a less massive F-type main sequence star in orbit with a more massive G-type giant star.[4] The overall apparent visual magnitude of the system is 4.75.[2]

The pair was first determined to be binary by F. G. W. Struve in 1832. Since then, the secondary has been seen to revolve approximately 45 degrees around the primary. A number of orbits have been computed, the most recent giving a period of approximately 1500 years.[4]

  1. ^ a b c Component 1, HIP 115088, database entry, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239.
  2. ^ a b c d e f g HR 8872, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line November 24, 2008.
  3. ^ a b c Component 2, HIP 115088, database entry, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239.
  4. ^ a b c d e f Docobo, Jos A. (2003). "Orbit and System Mass for the Visual Binary WDS 23186+6807AB". The Astronomical Journal. 126 (3): 1522–1525. Bibcode:2003AJ....126.1522D. doi:10.1086/377319. S2CID 54769846..
  5. ^ a b c "* omi Cep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 24, 2008.
  6. ^ a b c 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. ^ Entry 23186+6807, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line November 24, 2008.