Omega1 Scorpii

ω1 Scorpii, Latinised as Omega1 Scorpii, is a star in the zodiac constellation of Scorpius. With an apparent visual magnitude of 3.95[2] it can be seen with the naked eye, 0.22 degree north of the ecliptic. Parallax measurements of this star give an estimated distance of around 470 light years from the Sun. It is a member of the Scorpius–Centaurus association.[12]

For other stars with this Bayer designation, see ω Scorpii
ω1 Scorpii
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Scorpius
Right ascension 16h 06m 48.42692s[1]
Declination −20° 40′ 09.0902″[1]
Apparent magnitude (V) +3.95[2]
Characteristics
Spectral type B1 V[2]
U−B color index −0.82
B−V color index −0.05[3]
Variable type Beta Cephei variable[4]
Astrometry
Radial velocity (Rv)−3.1[5] km/s
Proper motion (μ) RA: −8.98[1] mas/yr
Dec.: −23.48[1] mas/yr
Parallax (π)6.92 ± 0.26 mas[1]
Distance470 ± 20 ly
(145 ± 5 pc)
Absolute magnitude (MV)−1.87[6]
Details
Mass11.4[7] M☉
Radius6.6[8] R☉
Luminosity9,120[7] L☉
Temperature26,530[2] K
Metallicity [Fe/H]−0.45±0.15[9] dex
Rotation14.4 h[4]
Rotational velocity (v sin i)105[4] km/s
Age5[7] Myr
Other designations
Jabhat al Akrab,[10] ω1 Sco, 9 Scorpii, BD−20°4405, HD 144470, HIP 78933, HR 5993, SAO 184123[11]
Database references
SIMBADdata

This is a B-type main sequence star with a stellar classification of B1 V.[2] It has a luminosity of 9,120 Suns, consistent with an isochronal age of 5 million years and an estimated mass of 11 solar masses.[7] The radius is about 6.6 times that of the Sun.[8] It has an effective temperature of 26,530 in its outer atmosphere.[2]

Omega1 Scorpii is a β Cephei star that undergoes non-radial pulsations at a rate of 15 cycles per day.[9] This is causing the surface temperature to fluctuate between 28,300 K and 22,600 K along the equator. The star is spinning rapidly with a projected rotational velocity of 105 km/s and an estimated rotation period of 14h.4. The poles of the star are inclined by around 60° to the line-of-sight from the Earth.[4]

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 Omega1 and Omega2 Scorpii. The girl, who is called Piri-ere-ua "Inseparable", keeps tight hold of her brother, who is not named.[13] (The IAU used a version of this story from Tahiti to name Mu2 Scorpii.)

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  2. Bragança, G. A.; et al. (November 2012), "Projected Rotational Velocities and Stellar Characterization of 350 B Stars in the Nearby Galactic Disk", The Astronomical Journal, 144 (5): 10, arXiv:1208.1674, Bibcode:2012AJ....144..130B, doi:10.1088/0004-6256/144/5/130, S2CID 118868235, 130.
  3. Deutschman, W. A.; et al. (February 1976), "The galactic distribution of interstellar absorption as determined from the Celescope catalog of ultraviolet stellar observations and a new catalog of UBV, H-beta photoelectric observations", Astrophysical Journal Supplement Series, 30: 97–225, Bibcode:1976ApJS...30...97D, doi:10.1086/190359.
  4. Berdyugina, S. V.; et al. (July 2003), "Surface imaging of stellar non-radial pulsations. II. The β Cephei star ω1 Sco", Astronomy and Astrophysics, 406: 281–285, Bibcode:2003A&A...406..281B, doi:10.1051/0004-6361:20030747.
  5. Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), "The Revision of the General Catalogue of Radial Velocities", Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, vol. 30, p. 57, Bibcode:1967IAUS...30...57E.
  6. 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, S2CID 119257644.
  7. Pecaut, Mark J.; et al. (February 2012), "A Revised Age for Upper Scorpius and the Star Formation History among the F-type Members of the Scorpius-Centaurus OB Association", Astrophysical Journal, 746 (2): 154, arXiv:1112.1695, Bibcode:2012ApJ...746..154P, doi:10.1088/0004-637X/746/2/154, S2CID 118461108. See table 7.{{citation}}: CS1 maint: postscript (link)
  8. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
  9. Daszyńska-Daszkiewicz, J.; Niemczura, E. (April 2005), "Metallicity of mono- and multiperiodic β Cephei stars", Astronomy and Astrophysics, 433 (3): 1031–1035, arXiv:astro-ph/0410442, Bibcode:2005A&A...433.1031D, doi:10.1051/0004-6361:20040397, S2CID 119340011.
  10. Allen, Richard Hinckley (1963) [1899], Star Names: Their Lore and Meaning (Revised ed.), New York: Dover Publications, p. 367, ISBN 0-486-21079-0.
  11. "* ome01 Sco". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-09-25.
  12. Jilinski, E.; et al. (March 2006), "Radial velocity measurements of B stars in the Scorpius-Centaurus association", Astronomy and Astrophysics, 448 (3): 1001–1006, arXiv:astro-ph/0601643, Bibcode:2006A&A...448.1001J, doi:10.1051/0004-6361:20041614, S2CID 17818058.
  13. Johannes Carl Andersen (1931) Myths and Legends of the Polynesians. 1995 Dover reprint, p.399–400.
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