Omicron Scorpii

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ο Scorpii
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Scorpius
Right ascension 16h 20m 38.2s
Declination –24° 10′ 10″
Apparent magnitude (V) +4.57[1]
Distance 880 ± 130 ly
(270 ± 40 pc)
Spectral type A4II/III[2]
Other designations
19 Scorpii, HD 147084, HIP 80079, HR 6081, SAO 184329.

Omicron Scorpii (ο Sco, ο Scorpii) is a star in the constellation Scorpius. It is a white A-type bright giant with an apparent magnitude of +4.57 located approximately 1,200 light years from Earth. This star has about eight times the mass of the Sun and is roughly 40 million years old.[2]

The star is radiating around 3,200 times the luminosity of the Sun from its outer atmosphere at an effective temperature of about 8,100 K.[1] While it was occasionally mentioned as a possible member of the Upper Scorpius sub-group in the Scorpius-Centaurus OB association during the 20th century,[1] it does not appear in more recent membership lists for this group[3] due to its small proper motion and small trigonometric parallax as measured by Hipparcos, which is suggestive that it is a background star unrelated to Scorpius-Centaurus.


  1. ^ a b c de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", Astronomy and Astrophysics 216 (1-2): 44–61, Bibcode:1989A&A...216...44D 
  2. ^ a b Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x 
  3. ^ de Zeeuw, P.T.; Hoogerwerf, R.; de Bruijne, J.H.J.; Brown, A.G.A. & Blaauw, A. (1999). "A Hipparcos Census of Nearby OB Associations". Astronomical Journal 117 (1): 354–399. arXiv:astro-ph/9809227. Bibcode:1999AJ....117..354D. doi:10.1086/300682.