Theta Aquarii is a star in the equatorial constellation of Aquarius. Its identifier is a Bayer designation that is Latinized from θ Aquarii, and abbreviated Tet Aqr or θ Aqr, respectively. It has the official name Ancha, which is pronounced . Visible to the naked eye at an apparent visual magnitude of 4.175, it is located at a distance of around from the Sun. The star is drifting closer to the Sun with a radial velocity of −14 km/s. 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. 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 Chinese name for Theta Aquarii itself is (, ). 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. 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.
References See run number 103 on page 114.
External links Image Ancha