Omicron Ophiuchi

ο Ophiuchi, Latinized as Omicron Ophiuchi, is a wide double star in the equatorial constellation of Ophiuchus. The co-moving pair are visible to the naked eye as a dim point of light, with the two components having apparent visual magnitudes of 5.14 and 6.59.[2] As of 2015, they had an angular separation of 10.0″ along a position angle of 354°.[9] The distance to both stars is approximately 281 light years based on parallax, and they are drifting closer to the Sun with a radial velocity of around −29 km/s.[5]

Omicron Ophiuchi
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
A
Right ascension 17h 18m 00.68112s[1]
Declination −24° 17′ 12.8535″[1]
Apparent magnitude (V) 5.14[2]
B
Right ascension 17h 18m 00.60620s[3]
Declination −24° 17′ 02.8150″[3]
Apparent magnitude (V) 6.59[2]
Characteristics
A
Spectral type G8III[2]
U−B color index 0.98[4]
B−V color index 1.046±0.005[2]
B
Spectral type F6IV-V[2]
U−B color index 0.05[4]
B−V color index 0.510±0.015[2]
Astrometry
A
Radial velocity (Rv)−28.97±0.13[1] km/s
Proper motion (μ) RA: −57.544[1] mas/yr
Dec.: −7.725[1] mas/yr
Parallax (π)11.5763 ± 0.1756[1] mas
Distance282 ± 4 ly
(86 ± 1 pc)
Absolute magnitude (MV)0.38[2]
B
Radial velocity (Rv)−29.70[5] km/s
Proper motion (μ) RA: −56.561[3] mas/yr
Dec.: −12.457[3] mas/yr
Parallax (π)11.6213 ± 0.0603[3] mas
Distance281 ± 1 ly
(86.0 ± 0.4 pc)
Absolute magnitude (MV)1.66[2]
Details
A
Radius12.30+0.20
−0.32[1] R☉
Luminosity75.3±1.3[1] L☉
Surface gravity (log g)2.69[6] cgs
Temperature4,849+63
−40[1] K
Metallicity [Fe/H]0.33[6] dex
B
Radius2.99+0.10
−0.12[3] R☉
Luminosity12.629±0.086[3] L☉
Temperature6,296+130
−105[3] K
Metallicity [Fe/H]0.23±0.08[2] dex
Other designations
ο Oph, 39 Ophiuchi, CD−24°13255, CCDM J17180-2417, WDS J17180-2417
A: GC 23344, HD 156349, HIP 84626, HR 6424, SAO 185238[7]
B: GC 23343, HD 156350, HIP 84625, HR 6425, SAO 185237[8]
Database references
SIMBADAB
A
B

The brighter member of the pair, designated component A, is an aging giant star with a stellar classification of G8III.[2] With the supply of hydrogen at its core exhausted, it has expanded to 12[1] times the radius of the Sun. The star is radiating 75[1] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,849 K.[1] The secondary star, component B, has a class of F6IV-V,[2] matching an F-type star with a luminosity class that is a blend of traits from a main sequence and a subgiant star. It has three[3] times the Sun's radius and is radiating 12.6 times the Sun's luminosity at 6,296 K.[3]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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.
  3. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  4. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  5. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  6. Luck, R. Earle (2014). "Parameters and Abundances in Luminous Stars". The Astronomical Journal. 147 (6): 137. Bibcode:2014AJ....147..137L. doi:10.1088/0004-6256/147/6/137.
  7. "omi Oph A". SIMBAD. Centre de données astronomiques de Strasbourg.
  8. "omi Oph B". SIMBAD. Centre de données astronomiques de Strasbourg.
  9. Mason, Brian D.; et al. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
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