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 |
| Characteristics | |
| Spectral type | F7IV-V+K2V |
| Astrometry | |
| Distance | 66.7 ± 0.8 ly (20.5 ± 0.3 pc) |
| Other designations | |
| Database references | |
| SIMBAD | The system |
| A | |
| B | |
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.
Naming
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]
References
External links
- Fuhrmann, Klaus (February 2008), "Nearby stars of the Galactic disc and halo - IV", Monthly Notices of the Royal Astronomical Society, 384 (1): 173–224, Bibcode:2008MNRAS.384..173F, doi:10.1111/j.1365-2966.2007.12671.x