Alpha2 Capricorni

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α² Capricorni
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Capricornus
Right ascension 20h 18m 03.3s
Declination −12° 32′ 41″
Apparent magnitude (V) +3.58
Absolute magnitude (V) +0.98+0.07
Distance 109±3 ly
(33±1 pc)
Spectral type G8 IIIb
Other designations
Gredi, Algedi, Secunda Giedi, Algiedi Secunda, 6 Capricorni, HR 7754, HD 192947, BD−12°5685, FK5 761, HIP 100064, SAO 163427, GC 28200, ADS 13645, CCDM J20181-1233
For other star systems with a similar Bayer designation, see Alpha Capricorni.

Alpha² Capricorni (α² Capricorni, abbreviated Alpha² Cap, α² Cap), also named Algedi,[2] is a star in the constellation of Capricornus. It is a yellow G-type giant with an apparent magnitude of +3.58 and is approximately 109 light years from the Sun. It forms part of the double star Alpha Capricorni along with α¹ Capricorni.


α² Capricorni (Latinised to Alpha² Capricorni) is the star's Bayer designation.

It bore the traditional names Secunda Giedi or Algiedi Secunda and shared the name Algedi (from the Arabic الجدي al-jadii 'the goat') with α¹ Capricorni. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[3] 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.[2]

In Chinese, 牛宿 (Niú Su), meaning Ox (asterism), refers to an asterism consisting of α² Capricorni, Beta Capricorni, ξ² Capricorni, Pi Capricorni, Omicron Capricorni and Rho Capricorni.[4] Consequently, α² Capricorni itself is known as 牛宿二 (Niú Su èr, English: the Second Star of Ox.)[5]


  1. ^ Carney, Bruce W.; et al. (March 2008), "Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars", The Astronomical Journal, 135 (3): 892–906, arXiv:0711.4984Freely accessible, Bibcode:2008AJ....135..892C, doi:10.1088/0004-6256/135/3/892 
  2. ^ a b "IAU Catalog of Star Names". Retrieved 28 July 2016. 
  3. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016. 
  4. ^ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  5. ^ (Chinese) 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.

External links[edit]

  • Kaler, Jim. "Algedi". Retrieved December 5, 2016.