Sigma2 Ursae Majoris

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For other stars with this Bayer designation, see σ Ursae Majoris.
Sigma2 Ursae Majoris
Sigma2 Ursae Majoris is located in 100x100
Sigma2 Ursae Majoris

Location of σ2 Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 09h 10m 23.2s
Declination +67° 08' 05"
Apparent magnitude (V) 4.85 + 8.16
Spectral type F7IV-V+K2V
Distance 66.7 ± 0.8 ly
(20.5 ± 0.3 pc)
Other designations
σ2 Ursae Majoris, σ2 UMa, Sigma2 UMa, 13 Ursae Majoris, BD+67 577, GC 12619, HD 78154, HIP 45038, HR 3616, PPM 16933, SAO 14788, WDS J09104+6708AB .
Database references
SIMBAD The system

Sigma2 Ursae Majoris (Sigma2 UMa, σ2 Ursae Majoris, σ2 UMa) is a binary star approximately 66.7 light years from Earth. The primary component, is a yellow-white F-type subgiant with an apparent magnitude of +4.85. The companion 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, Sigma² Ursae Majoris C, 205 arcseconds from the primary which is thought to be a line-of-sight co-incidence.


In Chinese, 三師 (Sān Shī), meaning Three Top Instructors, refers to an asterism consisting of σ2 Ursae Majoris and ρ Ursae Majoris. Consequently, σ2 Ursae Majoris itself is known as 三師三 (Sān Shī sān, English: the Third Star of Three Top Instructors.).[1]


External links[edit]