Omicron Cephei

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ο Cephei
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cepheus
A
Right ascension 23h 18m 37.493s
Declination +68° -6′ 41.20″[1]
Apparent magnitude (V) 4.86[2]
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]
A
Spectral type G8III[4]
B
Spectral type F6V[2]
Astrometry
A
Proper motion (μ) RA: 54.88[1] mas/yr
Dec.: 10.91[1] mas/yr
Parallax (π) 15.48 ± 0.55[5] mas
Distance 211 ± 7 ly
(65 ± 2 pc)
Absolute magnitude (MV) 0.8[note 1]
B
Proper motion (μ) RA: 45.70[3] mas/yr
Dec.: 13.19[3] mas/yr
Absolute magnitude (MV) 3.1[note 1]
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
A
Mass 2.35 ± 0.15[4] M☉
B
Mass 1.29[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][6]
Database references
SIMBAD data

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.[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]

Visual companion

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 4° [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

  1. ↑ 1.0 1.1 From apparent magnitude and parallax.

References

  1. ↑ 1.0 1.1 1.2 Component 1, HIP 115088, database entry, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 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. ↑ 3.0 3.1 3.2 Component 2, HIP 115088, database entry, The Hipparcos and Tycho Catalogues, 1997, CDS ID I/239.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 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, Bibcode: 2003AJ....126.1522D, doi:10.1086/377319.
  5. ↑ 5.0 5.1 5.2 CCDM J23186+6807AB -- Double or multiple star, database entry, SIMBAD. Accessed on line November 24, 2008.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 Entry 23186+6807, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line November 24, 2008.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 CCDM J23186+6807C -- Star in double system, database entry, SIMBAD. Accessed on line November 24, 2008.
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