23 Ursae Majoris

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23 Ursae Majoris A/B
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ursa Major
Right ascension 09h 31m 31.708s / 28.2s
Declination +63° 03′ 42.70″ / 43″
Apparent magnitude (V) +3.65 / +9.0
Distance 75.5 ± 1.1 ly
(23.1 ± 0.3 pc)
Spectral type A: F0IV
Other designations
23 UMa, h UMa, NN 3559, HR 3757,
HD 81937, BD +63 845, FK5 355, HIP 46733, SAO 14908, GC 13109,
ADS 7402, CCDM J09315+6303A/B

23 Ursae Majoris, or 23 UMa, is a binary star system in the constellation Ursa Major. It is approximately 75.5 light years from Earth.

The primary component is a yellow-white F-type subgiant with an apparent magnitude of +3.65. It has 2.9 times the Sun's radius and is emitting 15 times the luminosity of the Sun.[1] Orbiting at an angular separation of 22.7 arcseconds is the 9th magnitude secondary companion. There is a magnitude +10.5 optical companion at an angular separation of 99.6 arcseconds.

With φ, υ, θ, τ, e, and f, it composed the Arabic asterism Sarīr Banāt al-Na'sh, the Throne of the daughters of Na'sh, and al-Haud, the Pond,[2]


  1. ^ Boyajian, Tabetha S. et al. (February 2012), "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars", The Astrophysical Journal 746 (1): 101, arXiv:1112.3316, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101 . See Table 10.
  2. ^ Allen, Richard Hinckley (1899), Star-Names and Their Meanings, New York: G. E. Stechert, p. 442 

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