Alpha Andromedae (α Andromedae, abbreviated Alpha And or α And), officially named Alpheratz , is 97 light-years from the Sun and is the brightest star in the constellation of Andromeda when Beta Andromedae undergoes its periodical dimming. Immediately northeast of the constellation of Pegasus, it is the upper left star of the Great Square of Pegasus. Although it appears to the naked eye as a single star, with overall apparent visual magnitude +2.06, it is actually a binary system composed of two stars in close orbit. The chemical composition of the brighter of the two stars is unusual as it is a mercury-manganese star whose atmosphere contains abnormally high levels of mercury, manganese, and other elements, including gallium and xenon. It is the brightest mercury-manganese star known. Nomenclature α Andromedae (Latinised to Alpha Andromedae) is the star's Bayer designation. Ptolemy considered the star (system) to be shared by Pegasus and Johann Bayer assigned it a designation in both constellations: Alpha Andromedae (α And) and Delta Pegasi (δ Peg). Since the IAU standardized constellation boundaries and widely published them two years after in 1930, the Pegasi alternate name has dropped from use, putting it slightly outside of that constellation. To most European centres of learning the star bore names Alpheratz () or the cognate simplification Alpherat or the other part of the fabled description: Sirrah . The origin of these three, the Arabic phrasal name, is سرة الفرس "navel of the mare/horse", attracting a hard consonant not present above due to a following vowel. The horse corresponds equivalently to the winged horse of the Greeks, Pegasus. The star is in almost all depictions part of the main asterism of Pegasus and Andromeda. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 confirmed Alpheratz as the name for the main star. Other terms for this star used by some medieval astronomers writing were راس المراة المسلسلة rās al-mar'a al-musalsala (head of the woman in chains), al-kaff al-khaḍīb and kaff al-naṣīr (palm of the faithful). The chained woman referenced Andromeda. In the Hindu lunar zodiac, this star, together with the other stars in the Great Square of Pegasus (α, β, and γ Pegasi), makes up the nakshatras of Pūrva Bhādrapadā and Uttara Bhādrapadā. In Chinese, (), meaning wall, refers to an asterism consisting