Omega Ophiuchi

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ω Ophiuchi
Ophiuchus constellation map.svg
Red circle.svg

Location of ω Ophiuchi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension 16h 32m 08.19983s[1]
Declination −21° 27′ 59.0120″[1]
Apparent magnitude (V) 4.45[2]
Spectral type A7p[3]
U−B color index +0.13[2]
B−V color index +0.11[2]
Variable type α² CVn[4]
Radial velocity (Rv) +2.50[5] km/s
Proper motion (μ) RA: +21.12[1] mas/yr
Dec.: +35.26[1] mas/yr
Parallax (π) 19.34 ± 0.21[1] mas
Distance 169 ± 2 ly
(51.7 ± 0.6 pc)
Absolute magnitude (MV) 0.88[6]
Mass 2.06[7] M
Radius 3.0[7] R
Luminosity 37.27[6] L
Surface gravity (log g) 3.94[8] cgs
Temperature 8,541[8] K
Metallicity [Fe/H] -0.47[9] dex
Rotational velocity (v sin i) 48[8] km/s
Other designations
BD-21 4381, 9 Ophiuchi, FK5 3307, GC 22221, HIP 80975, HR 6153, HD 148898, SAO 184450
Database references

Omega Ophiuchi (ω Oph) is a class A7[3] star in the constellation Ophiuchus. Its apparent magnitude is 4.45[2] and it is approximately 168.6 light years away based on parallax.[1]

It is an α² CVn variable, ranging from 4.51 to 4.44 magnitude with a period of 2.99 days.[4]


  1. ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b c d Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D. 
  3. ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H. 
  4. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 1. Bibcode:2009yCat....1.2025S. 
  5. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. 
  6. ^ a b Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971Freely accessible. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015.  Vizier catalog entry
  7. ^ a b Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555. arXiv:astro-ph/9911002Freely accessible. Bibcode:1999A&A...352..555A.  Vizier catalog entry
  8. ^ a b c David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154Freely accessible. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.  Vizier catalog entry
  9. ^ Soubiran, Caroline; Le Campion, Jean-François; Brouillet, Nathalie; Chemin, Laurent (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics. 591: A118. arXiv:1605.07384Freely accessible. Bibcode:2016A&A...591A.118S. doi:10.1051/0004-6361/201628497.