Algiedi
Algiedi or Algedi (from Arabic الجدي, DMG al-ǧady , the billy goat ') is the proper name of the star Alpha Capricorni (α Cap) in the constellation Capricorn .
Algiedi is a double star , the two components of which are at a relatively large distance of 6.5 arc minutes from each other, so that they can be separated with the naked eye, similar to Mizar and Alkor in the constellation Great Bear . However, the two components of Algiedi are at different distances from the earth , from our point of view they are only incidentally in almost the same direction, so there is an optical double star here.
Due to their own individual movement , the two stars slowly move further apart in the sky as seen from the earth. They had their smallest mutual distance about 9,000 years ago with about 2.5 arc minutes.
The western of the two stars, Alpha1 Capricorni ("Prima Giedi") with an apparent magnitude of 4.4 mag, is a yellow supergiant of the spectral type G3 Ib and 570 light years away, while the eastern of the two stars, 3.6 mag, is bright (and thus appearing twice as bright) Alpha2 Capricorni ("Secunda Giedi"), a yellow giant star of the spectral type G8.5 III-IV, is only 106 light years away from Earth. Both stars are again multiple star systems.
According to the “IAU Catalog of Star Names” of the Working Group on Star Names (WGSN) of the IAU for the standardization of star names, the name in the form “Algedi” has only been permitted for the lighter Alpha2 Capricorni since 2016.
See also
Individual evidence
- ↑ Bulletin of the IAU Working Group on Star Names, No. 2. IAU Division C Education, Outreach and Heritage, 2016 ( PDF; 158 kB ).