Astronomy:Omega2 Scorpii

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Short description: Variable star
For other stars with this Bayer designation, see ω Scorpii
ω2 Scorpii
Location of ω2 Scorpii (circled in red)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Scorpius
Right ascension  16h 07m 24.32818s[1]
Declination −20° 52′ 07.5518″[1]
Apparent magnitude (V) +4.320[2]
Characteristics
Evolutionary stage horizontal branch[3]
Spectral type G6/8III[4]
U−B color index +0.494[2]
B−V color index +0.850[2]
Astrometry
Radial velocity (Rv)−5.4[5] km/s
Proper motion (μ) RA: +44.81[1] mas/yr
Dec.: −45.42[1] mas/yr
Parallax (π)11.22 ± 0.32[1] mas
Distance291 ± 8 ly
(89 ± 3 pc)
Absolute magnitude (MV)−0.62[6]
Details
Mass3.27[6] M☉
Radius15.0[7] R☉
Luminosity163[7] L☉
Surface gravity (log g)2.62±0.11[8] cgs
Temperature5,363±42[8] K
Metallicity [Fe/H]+0.03±0.05[8] dex
Age282[6] Myr
Other designations
Jabhat al Akrab,[9] ω2 Sco, 10 Scorpii, BD−20°4408, HD 144608, HIP 78990, HR 5997, SAO 184135[10]
Database references
SIMBADdata

ω2 Scorpii, Latinised as Omega2 Scorpii, is a suspected[11] variable star in the zodiac constellation of Scorpius. A component of the visual double star ω Scorpii, it is bright enough to be seen with the naked eye having an apparent visual magnitude of +4.320.[2] The distance to this star, as determined using parallax measurements,[1] is around 291 light years. The visual magnitude of this star is reduced by 0.38 because of extinction from interstellar dust.[6]

It is 0.05 degree north of the ecliptic, so can be occulted by the moon and planets.

This is a G-type giant star with a stellar classification of G6/8III.[4] With an estimated age of 282 million years,[6] it is an evolved, thin disk star that is currently on the red horizontal branch.[3] The interferometry-measured angular diameter of this star is 1.63 ± 0.10 mas,[12] which, at its estimated distance, equates to a physical radius of nearly 16 times the radius of the Sun.[13] It has 3.27 times the mass of the Sun,[6] and radiates 141 times the Sun's luminosity[14] The effective temperature of the star's outer atmosphere is 5,363 K.[8]

Names

In the Cook Islands, a traditional story is told of twins who flee their parents into the sky and become the pair of stars Omega2 and Omega1 Scorpii. The girl, who is called Piri-ere-ua "Inseparable", keeps tight hold of her brother, who is not named.[15] (The IAU used a version of this story from Tahiti to name Mu2 Scorpii.)

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V. 
  2. ↑ 2.0 2.1 2.2 2.3 Kozok, J. R. (September 1985), "Photometric observations of emission B-stars in the southern Milky Way", Astronomy and Astrophysics Supplement Series 61: 387–405, Bibcode: 1985A&AS...61..387K. 
  3. ↑ 3.0 3.1 Afşar, M. et al. (July 2012), "Chemical Compositions of Thin-disk, High-metallicity Red Horizontal-branch Field Stars", The Astronomical Journal 144 (1): 20, doi:10.1088/0004-6256/144/1/20, 20, Bibcode: 2012AJ....144...20A. 
  4. ↑ 4.0 4.1 Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Declinations -26°.0 to -12°.0, 4, Bibcode: 1988mcts.book.....H. 
  5. ↑ Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication (Carnegie Institute of Washington D.C.), Bibcode: 1953GCRV..C......0W. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Takeda, Yoichi et al. (August 2008), "Stellar Parameters and Elemental Abundances of Late-G Giants", Publications of the Astronomical Society of Japan 60 (4): 781–802, doi:10.1093/pasj/60.4.781, Bibcode: 2008PASJ...60..781T. 
  7. ↑ 7.0 7.1 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  8. ↑ 8.0 8.1 8.2 8.3 Prugniel, P. et al. (2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics 531: A165, doi:10.1051/0004-6361/201116769, Bibcode: 2011A&A...531A.165P. 
  9. ↑ Allen, Richard Hinckley (1963), Star Names: Their Lore and Meaning (Revised ed.), New York: Dover Publications, p. 367, ISBN 0-486-21079-0, https://archive.org/details/starnamestheirlo00alle/page/367. 
  10. ↑ "* ome02 Sco". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+ome02+Sco. 
  11. ↑ Sterken, C. (January 1977), "uvby Photometry of the Suspected Variable omega2 Sco", Information Bulletin on Variable Stars 1230: 1, Bibcode: 1977IBVS.1230....1S. 
  12. ↑ Richichi, A.; Percheron, I. (May 2002), "CHARM: A Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics 386 (2): 492–503, doi:10.1051/0004-6361:20020236, Bibcode: 2002A&A...386..492R. 
  13. ↑ Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3 ed.), Birkhäuser, ISBN 3-540-29692-1, https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41. . The radius (R*) is given by:
    2⋅R*=(89⋅1.63⋅10−3) AU0.0046491 AU/R⨀≈31.2⋅R⨀
  14. ↑ McDonald, I. et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society 427 (1): 343–57, doi:10.1111/j.1365-2966.2012.21873.x, Bibcode: 2012MNRAS.427..343M. 
  15. ↑ Johannes Carl Andersen (1931) Myths and Legends of the Polynesians. 1995 Dover reprint, p.399–400.



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