Mu Ursae Majoris
Mu Ursae Majoris (μ Ursae Majoris, abbreviated Mu UMa, μ UMa), formally named Tania Australis /ˈteɪniə ɔːˈstreɪlɪs/, is a binary star in the constellation of Ursa Major. An apparent visual magnitude of +3.06 places it among the brighter members of the constellation. Parallax measurements give an estimated distance of roughly 230 light-years (71 parsecs) from the Sun, with a margin of error of 4%.
Location of μ Ursae Majoris (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 10h 22m 19.73976s |
| Declination | +41° 29′ 58.2691″ |
| Apparent magnitude (V) | +3.06 |
| Characteristics | |
| Evolutionary stage | AGB |
| Spectral type | M0 IIIab |
| U−B color index | +1.90 |
| B−V color index | +1.59 |
| Variable type | suspected |
| Astrometry | |
| Radial velocity (Rv) | −21.30±1.66 km/s |
| Proper motion (μ) | RA: –81.47 mas/yr Dec.: +35.34 mas/yr |
| Parallax (π) | 17.7987 ± 0.3933 mas |
| Distance | 183 ± 4 ly (56 ± 1 pc) |
| Absolute magnitude (MV) | −1.11±0.083 |
| Orbit | |
| Period (P) | 230.089 days |
| Semi-major axis (a) | 0.0028″ |
| Eccentricity (e) | 0.061 |
| Inclination (i) | 13.6° |
| Periastron epoch (T) | 2425577.030 JD |
| Argument of periastron (ω) (secondary) | 236.4° |
| Semi-amplitude (K1) (primary) | 7.40 km/s |
| Details | |
| Mass | 6.3 M☉ |
| Radius | 75 R☉ |
| Luminosity | 977–1,200 L☉ |
| Surface gravity (log g) | 1.0 cgs |
| Temperature | 3,899 K |
| Metallicity [Fe/H] | +0.00 dex |
| Rotational velocity (v sin i) | 7.5 km/s |
| companion | |
| Mass | 0.96 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
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