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Sargas

Theta Scorpii
Theta Scorpii is located in 100x100
Theta Scorpii

θ (circled) in the constellation Scorpius.
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 17h 37m 19.12985s
Declination –42° 59′ 52.1808″
Apparent magnitude (V) 1.84 (1.862 + 6.22)
Characteristics
Spectral type F0 II
U−B color index +0.21
B−V color index +0.40
Astrometry
Radial velocity (Rv) +1.4 km/s
Proper motion (μ) RA: +5.54 mas/yr
Dec.: –3.12 mas/yr
Parallax (π) 10.86 ± 1.49mas
Distance approx. 300 ly
(approx. 90 pc)
Details
Mass 5.66 ± 0.65 M
Radius 26 R
Luminosity 1,834 L
Surface gravity (log g) 2.4 ± 0.2 cgs
Temperature 7,268 K
Rotational velocity (v sin i) 125 km/s
Other designations
Sargas, Girtab, 160 G. Scorpii, CCDM 17373-4300, FK5 654, HD 159532, HIP 86228, HR 6553, SAO 228201.

Theta Scorpii (θ Scorpii, abbreviated Theta Sco, θ Sco), also named Sargas, 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, which yields an estimate of roughly 300 light years (90 parsecs) from the Sun.

θ Scorpii (Latinised to Theta Scorpii) is the system's Bayer designation.

It bore the traditional name Sargas, of Sumerian origin. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Sargas for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.

In Chinese astronomy, it is referred to as 尾宿五 (Wěisuwǔ), the Fifth Star of the Tail.

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, 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.


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