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 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.