Sigma Ursae Majoris

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The Bayer designation Sigma Ursae Majoris (σ UMa / σ Ursae Majoris) is shared by two star systems, σ¹ Ursae Majoris and σ² Ursae Majoris, in the constellation Ursa Major. They are separated by 0.33° on the sky.

[edit] σ¹ Ursae Majoris

**σ¹ Ursae Majoris**
Observation data Equinox J2000.0
Constellation	Ursa Major
Right ascension	09^h 08^m 23.6^s
Declination	+66° 52' 24"
Apparent magnitude (V)	+5.15
Distance	500 ± 45 ly (153 ± 14 pc)
Spectral type	K5III
Other designations
11 Ursae Majoris, HR 3609, HD 77800, BD+67 573, HIP 44857, SAO 14769, GC 12576

Sigma-1 Ursae Majoris is an orange K-type giant with an apparent magnitude of +5.15. It is approximately 500 light years from Earth.

[edit] σ² Ursae Majoris

**σ² Ursae Majoris**
Observation data Equinox J2000.0
Constellation	Ursa Major
Right ascension	09^h 10^m 23.2^s
Declination	+67° 08' 05"
Apparent magnitude (V)	4.85 + 8.16
Distance	66.7 ± 0.8 ly (20.5 ± 0.3 pc)
Spectral type	F7IV-V+K2V
Other designations
13 Ursae Majoris, HR 3616, HD 78154, BD+67 577, HIP 45038, SAO 14788, GC 12619, ADS 7203, CCDM 09105+6707

Sigma-2 Ursae Majoris is a binary star approximately 66.7 light years from Earth. The primary component, Sigma-2 Ursae Majoris A, is a yellow-white F-type subgiant with an apparent magnitude of +4.85. The companion, Sigma-2 Ursae Majoris B, is an orange K-type main sequence dwarf with an apparent magnitude of +8.16. The two stars have a semi-major axis on the sky of 6 arcseconds and have an orbital period of 1067 years. There is a third component, Sigma-2 Ursae Majoris C, 205 arcseconds from the primary which is thought to be a line-of-sight co-incidence.