Chi Ursae Majoris

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Chi Ursae Majoris
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings
Cercle rouge 100%.svg

Location of χ Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 11h 46m 03.0s
Declination +47° 46' 46"
Apparent magnitude (V) +3.69
Distance 196 ± 7 ly
(60 ± 2 pc)
Spectral type K0.5IIIb
Other designations
Alkaphrah, El Koprah, χ Ursae Majoris, χ UMa, Chi UMa, 63 Ursae Majoris, BD+48 1966, FK5 441, GC 16137, HD 102224, HIP 57399, HR 4518, PPM 52620, SAO 43886
Chi Ursae Majoris (top) and NGC 3877 (bottom)

Chi Ursae Majoris (Chi UMa, χ Ursae Majoris, χ UMa) is a star in the constellation Ursa Major. It has the traditional names Alkafzah, Alkaphrah, and El Koprah.

Chi Ursae Majoris is an orange K-type giant with an apparent magnitude of +3.69. It is approximately 196 light years from Earth. This star has 20.8 ± 0.8 times the radius of the Sun.[1]

In Chinese astronomy, Alkafzah is called Tai Yang Show, "the Sun Governor".[2] The name was possibly derived from the word 太陽守, Pinyin: Tàiyángshǒu, meaning Guard of the Sun, because this star is marking itself and stand alone in Guard of the Sun asterism, Purple Forbidden enclosure (see : Chinese constellation).

The Spiral Galaxy in Ursa Major, NGC 3877 (= H I.201), type Sc, is best found from Chi Ursae Majoris, which is almost exactly 15 arc minutes north of the galaxy.

See also[edit]


  1. ^ Nordgren, Tyler E. et al. (December 1999), "Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer", The Astronomical Journal 118 (6): 3032–3038, Bibcode:1999AJ....118.3032N, doi:10.1086/301114 
  2. ^ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Ursa Major