Theta Aquarii
Theta Aquarii (θ Aquarii, abbreviated Theta Aqr, θ Aqr), officially named Ancha (distinguish Ankaa, with the same pronunciation), is a star in the equatorial constellation of Aquarius. Visible to the naked eye at apparent magnitude 4.175, it is located at a distance of around from the Sun. Since it is near the ecliptic it can be occulted by the Moon, or very rarely by planets. Nomenclature. "θ Aquarii" (Latinised to "Theta Aquarii") is the star's Bayer designation. It bore the traditional name "Ancha"; Medieval Latin for "the haunch". 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 "Ancha" for this star on 12 September 2016, and it is now so included in the List of IAU-approved Star Names. In Chinese, (), meaning "Weeping", refers to an asterism consisting of Theta Aquarii and Rho Aquarii. Consequently, the Chinese name for Theta Aquarii itself is (, ). Possibly, the name "Lei", meaning "tears (weeping)" in Chinese, derives from the Chinese name for this star. Properties. Ancha belongs to the spectral class G8 with a luminosity class of III–IV suggesting that, at an  age of 437 million years, this star is part way between the subgiant and giant stages of its evolution. Estimates of the star's mass range from 2.39 to 2.78 times the Sun's mass, with a radius of about 12 times that of the Sun. It is radiating from 72 to 83 times as much luminosity as the Sun from its enlarged outer envelope at an effective temperature of 4,864 K. At this heat, the star glows with the yellow hue of a G-type star.