Epsilon Scorpii is a binary star in the southern zodiac constellation of Scorpius. The primary component has the proper name Larawag . It has an apparent visual magnitude of around +2.3, making it the fifth-brightest member of the constellation. Parallax measurements made during the Hipparcos mission provide a measured distance of .
Characteristics Larawag has a stellar classification of K1 III, which indicates it has exhausted the supply of hydrogen at its core and evolved into a giant star. Its mass is estimated at 1.41 times the mass of the Sun, and its radius is roughly 13 times that of the Sun. Presently it is generating energy through the nuclear fusion of helium at its core, which, considering the star's composition, places it along an evolutionary branch termed the horizontal branch. In the color-magnitude diagram, the star is located in the red clump. The star's outer atmosphere has an effective temperature of 4,522 K, giving it the orange hue of a cool K-type star.
It is classified as a suspected variable star with a magnitude range of 2.23 to 2.35, although a study of Hipparcos photometry showed a variation of no more than 0.01–0.02 magnitudes. It is an X-ray source with a luminosity of .
In 2018 it was found that Epsilon Scorpii A has a proper motion companion separated by 14.4", making it a binary star sytstem. The companion, B, is much smaller and fainter than the primary, with 0.26% of the mass, 0.29% the radius, and less than 1% of the Sun's luminosity.
Nomenclature
ε Scorpii, Latinised to Epsilon Scorpii, is the star's Bayer designation.
The star bore the traditional name Larawag in the culture of the Wardaman people of the Northern Territory of Australia, meaning clear sighting. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Larawag for Epsilon Scorpii A on 19 November 2017 and it is now so included in the List of IAU-approved Star Names.
Patrick Moore introduced the name Wei as Chinese name for this star. However, this seems to be a misreading, as Chinese (, English Tail) refers to an asterism (i.e. Chinese constellation) consisting of Epsilon Scorpii, Mu1 Scorpii, Zeta Scorpii, Eta Scorpii, Theta Scorpii, Iota Scorpii, Kappa Scorpii, Lambda Scorpii and Upsilon Scorpii. 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, . Consequently, the name for Epsilon Scorpii itself is (), which means "the Second Star of Tail". 香港太空館 - 研究資源 - 亮星中英對照表 , Hong Kong Space Museum. Accessed on line November 23, 2010.Ridpath, Ian, Star Tales.
In culture Epsilon Scorpii appears on the flag of Brazil, symbolising the state of Ceará.
References