10 Ursae Majoris
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lynx |
| Right ascension | 09h 00m 38.38067s |
| Declination | +41° 46′ 58.6051″ |
| Apparent magnitude (V) | 3.960 (4.18 / 6.48) |
| Characteristics | |
| Spectral type | F3V + K0V |
| U−B color index | +0.04 |
| B−V color index | +0.43 |
| Astrometry | |
| Radial velocity (Rv) | 26.4 ± 0.9 km/s |
| Proper motion (μ) | RA: -474.31 mas/yr Dec.: -204.21 mas/yr |
| Parallax (π) | 62.23±0.68 mas |
| Distance | 52.4 ± 0.6 ly (16.1 ± 0.2 pc) |
| Absolute magnitude (MV) | +2.93 |
| Orbit | |
| Period (P) | 7691.0 ± 1.8 d |
| Semi-major axis (a) | 0.64566 ± 0.00056″ |
| Eccentricity (e) | 0.15075 ± 0.00084 |
| Inclination (i) | 131.366 ± 0.099° |
| Longitude of the node (Ω) | 203.74 ± 0.10° |
| Periastron epoch (T) | JD 2449263.1 ± 9.1 |
| Argument of periastron (ω) (secondary) | 32.30 ± 0.44° |
| Details | |
| 10 UMa A | |
| Mass | 1.44 M☉ |
| Radius | 1.518 R☉ |
| Luminosity | 4.285 L☉ |
| Temperature | 6740 K |
| 10 UMa B | |
| Mass | 0.89 M☉ |
| Radius | 0.965 R☉ |
| Luminosity | 0.638 L☉ |
| Temperature | 5250 K |
| Other designations | |
| 10 UMa, BD+42°1956, FK5 339, GJ 332, HD 76943, HIP 44248, HR 3579, SAO 42642 | |
| Database references | |
| SIMBAD | 10 UMa |
| ARICNS | 10 UMa A |
| 10 UMa B | |
10 Ursae Majoris is a binary star system in the northern constellation of Lynx. It is visible to the naked eye as a faint star with a combined apparent visual magnitude of 3.960. This system is fairly close to the Sun, at 53 light-years (16.1 pc) away from Earth. It is the third-brightest object in Lynx. John Flamsteed, England’s first Astronomer Royal, wrongly catalogued this star as part of Ursa Major, hence its designation. The system is moving further from the Earth with a heliocentric radial velocity of 26.4 km/s. It is a probable member of the Hyades supercluster.
This is a spectroscopic binary—orbital motion from the two stars can be detected by Doppler shifts in their spectra. In this case, the two stars can also be split by differential astrometry. The magnitude 4.18 primary has a mass of 1.44 M☉ and the fainter secondary, 0.89 M☉. The primary is an F-type main-sequence star radiating 4.3 times the Sun's luminosity, and the magnitude 6.48 secondary is K-type with 0.6 times the luminosity of the Sun. The two orbit each other every 21.057 years with an eccentricity of 0.15.