Omicron Cephei

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ο Cephei
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cepheus
Component A B
Right ascension 23h 18m 23h 18m
  37.493s 37.115s
Declination +68° 06′[1] +68° 06′[2]
  41.20″ 38.65″
Apparent magnitude (V) 4.86[3] 7.13[3]
Characteristics
Spectral type G8III[4] F6V[3]
U-B color index +0.49[3]
B-V color index +0.84[3]
R-I color index +0.45[3]
Astrometry
Proper motion:  
RA α cos δ)  54.88[1] mas/yr  45.70[2] mas/yr 
Dec. δ)  10.91[1] mas/yr  13.19[2] mas/yr 
Parallax (π) 15.48 ± 0.55[5] mas
Distance 211 ± 7 ly
(65 ± 2 pc)
Absolute magnitude (MV) 0.8[note 1] 3.1[note 1]
Details
Mass 2.35 ± 0.15[4] M 1.29[4] M
Orbit[4]
Period (P) 1505 ± 40 y
Semimajor axis (a) 3.13 ± 0.12
Eccentricity (e) 0.439 ± 0.020
Inclination (i) 16.0 ± 4.0°
Longitude of node (Ω) 4.5 ± 4.5°
Periastron epoch (T) B1692 ± 20
Argument of periastron (ω)
(secondary)
93.0 ± 20.0°
Database references
SIMBAD data
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][6]

Omicron Cephei (Omicron Cep, ο Cephei, ο Cep) is a binary star in the constellation of Cepheus.[5] It consists of a less massive K-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.[3]

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]


Visual companion[edit]

CCDM J23186+6807C
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cepheus
Right ascension 23h 18m 37.5s[7]
Declination +68° 07′ 26″[7]
Apparent magnitude (V) 12.8[7]
Position (relative to A)
Epoch of observation 1912
Angular distance 45.6 [6]
Position angle [6]
Other designations
STF 3001C, ADS 16666 C, IDS 23145+6734 C, WDS 23186+6807C.[6][7]
Database references
SIMBAD data

There is a visual companion, CCDM J23186+6807C, to the binary star. It has an approximate apparent visual magnitude of 12.8 and is located approximately 45 arcseconds away from it.[6][7]

Notes[edit]

  1. ^ a b From apparent magnitude and parallax.

References[edit]

  1. ^ a b c Component 1, HIP 115088, database entry, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239.
  2. ^ a b c Component 2, HIP 115088, database entry, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239.
  3. ^ 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.
  4. ^ a b c d e f Orbit and System Mass for the Visual Binary WDS 23186+6807AB, José A. Docobo, Vakhtang S. Tamazian, Manuel Andrade, and Norik D. Melikian, Astronomical Journal 126, #3 (September 2003), pp. 1522–1525, Bibcode2003AJ....126.1522D, doi:10.1086/377319.
  5. ^ a b c CCDM J23186+6807AB -- Double or multiple star, database entry, SIMBAD. Accessed on line November 24, 2008.
  6. ^ a b c d e Entry 23186+6807, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line November 24, 2008.
  7. ^ a b c d e CCDM J23186+6807C -- Star in double system, database entry, SIMBAD. Accessed on line November 24, 2008.