Theta Scorpii
Theta Scorpii is a binary star in the southern zodiac constellation of Scorpius. The apparent visual magnitude of this star is +1.87, 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 300 light-years from the Sun.
The two components are designated θ Scorpii A and B.Nomenclature
θ 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 for multiple star systems, and adopted by the International Astronomical Union.
It bore the traditional name Sargas, of Sumerian origin. Another possible origin is Persian for Arrow Head سر گز. The name 'Sar Gaz' is used in Iran as a star name, and was used for timing irrigation water shares. In 2016, the IAU organized a Working Group on Star Names to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. 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.
In Chinese, 尾宿, meaning Tail, refers to an asterism consisting of Theta Scorpii, Epsilon Scorpii, Zeta1 Scorpii and Zeta2 Scorpii, Eta Scorpii, Iota1 Scorpii and Iota2 Scorpii, Kappa Scorpii, Lambda Scorpii, Mu1 Scorpii and Upsilon Scorpii. Consequently, the Chinese name for Theta Scorpii itself is 尾宿五, "the Fifth Star of Tail".Properties
The primary is an evolved bright giant star with a stellar classification of F0 II. With a mass 5.7 times that of the Sun, it has expanded to about 26 times the Sun's radius. It is radiating 1,834 times as much luminosity as the Sun from its outer envelope at an effective temperature of 7,268 K, giving it the yellow-white hued glow of an F-type star. This star is rotating rapidly, giving it an oblate shape with an equatorial radius 19% larger than the polar radius.
The magnitude 5.36 companion is at an angular separation of 6.470 arcseconds.Modern legacy
θ Scorpii appears on the flag of Brazil, symbolising the state of Alagoas.
