Theta Scorpii

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Theta Scorpii
Location of θ Scorpii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 17h 37m 19.12985s[1]
Declination −42° 59′ 52.1808″[1]
Apparent magnitude (V) 1.84 (1.862 + 6.22)[2]
Characteristics
Spectral type F0 II[3]
U−B color index +0.21[4]
B−V color index +0.40[4]
Distance
329 ± 9 ly
(101 ± 3 pc)
Absolute magnitude (MV)−2.71[7]
Details
Rotational velocity (v sin i)
125[9] km/s
HR 6553, SAO 228201, CCDM J17373−4300[10]
Database references
SIMBADdata

Theta Scorpii (θ Scorpii, abbreviated Theta Sco, θ Sco) is a

apparent visual magnitude of this star is +1.87,[4] making it readily visible to the naked eye and one of the brightest stars in the night sky. It is sufficiently near that the distance can be measured directly using the parallax technique and such measurements obtained during the Hipparcos mission yield an estimate of approximately 329 light-years (101 parsecs) from the Sun
.

The two components are designated θ Scorpii A (officially named Sargas /ˈsɑːrɡæs/, the traditional name for the system)[11][12] and B.

Nomenclature

θ Scorpii (Latinised to Theta Scorpii) is the system's Bayer designation. The designations of the two components as Theta Scorpii A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[13]

It bore the traditional name Sargas, of

multiple systems.[17] It approved the name Sargas for the star θ Scorpii A on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[12]

In

Chinese name for Theta Scorpii itself is 尾宿五 (Wěi Xiù wǔ), "the Fifth Star of Tail".[19]

Properties

The primary (θ Scorpii A) is an

oblate shape with an equatorial radius 19% larger than the polar radius.[9] The equatorial radius is about 36 R☉ while the polar radius is only about 26 R☉. This rapid rotation suggests that it formed via the merger of a binary star system.[6]

A magnitude 5.36 companion has been reported at an

arcseconds,[20] but subsequent observers have failed to detect it, so it probably does not exist. However, a secondary, designated θ Scorpii B, has been detected at an angular separation of 0.538 arcseconds in 1991 by the Hipparcos satellite.[6]

Modern legacy

Theta Scorpii appears on the flag of Brazil, symbolising the state of Alagoas.[21]

References

  1. ^
    S2CID 18759600
    .
  2. doi:10.1888/0333750888/2862
    .
  3. ^
    Bibcode:1978mcts.book.....H
    .
  4. ^
    Bibcode:1966CoLPL...4...99J
    .
  5. Bibcode:1953GCRV..C......0W
    .
  6. ^
    doi:10.1093/mnras/stac991
    .
  7. S2CID 119257644
    .
  8. S2CID 119828317
    .
  9. ^
    S2CID 119273474
    .
  10. ^ "* tet Sco". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-02-18.
  11. ISBN 978-1-931559-44-7
    .
  12. ^ a b "Naming Stars". IAU.org. Retrieved 3 March 2018.
  13. arXiv:1012.0707 [astro-ph.SR
    ].
  14. ISBN 0-486-23673-0
    .
  15. ^ Nash, Harriet; et al. (2012). Traditional Timing of Qanat Water Shares. International Conference on Traditional Knowledge for Water. Retrieved 26 April 2017.
  16. ^ "IAU Working Group on Star Names (WGSN)". International Astronomical Union. Retrieved 22 May 2016.
  17. ^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  18. ISBN 978-986-7332-25-7
    .
  19. ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2008-10-25 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  20. S2CID 14878976
    .
  21. ^ "Astronomy of the Brazilian Flag". Flags of the World.

External links

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