Alpha Capricorni
Alpha Capricorni is an optical double star in the constellation of Capricornus. The two physically unrelated components are designated:
They are separated by 0.11° on the sky, and resolvable with the naked eye, similar to Mizar and Alcor. α¹ Capricorni is fainter than α² Capricorni.
Nomenclature
α Capricorni is the system's Bayer designation; α1 and α2 Capricorni, those of the two components.Alpha Capricorni bore the traditional names Algedi, Algiedi, Al Giedi or Giedi, derived from the Arabic الجدي ''al-jady "the billy goat" or "kid". It also refers to the entire constellation of Capricornus. Giedi is sometimes also associated with Beta Capricorni. α1 and α2 Capricorni were also called Prima Giedi and Secunda Giedi, respectively. In 2016, the International Astronomical Union organized a IAU [Working Group on Star Names|Working Group on Star Names] to catalogue and standardize proper names for stars. The WGSN approved the name Algedi for α2 Capricorni'' on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.
Alpha Capricorni is known as 牛宿二 in Chinese astronomy.