23 Ursae Majoris
23 Ursae Majoris, or 23 UMa, is a binary star system in the constellation Ursa Major, located is approximately 77.7 light years from the Sun. It has the Bayer designation h Ursae Majoris; 23 Ursae Majoris is the Flamsteed designation. The system is visible to the naked eye as a yellow-white hued star with an apparent visual magnitude of +3.65. It is moving closer to the Earth with a heliocentric radial velocity of −10 km/s.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 09h 31m 31.70873s |
| Declination | +63° 03′ 42.7013″ |
| Apparent magnitude (V) | +3.65 / +9.0 |
| Characteristics | |
| Spectral type | F0IV |
| B−V color index | 0.360±0.015 |
| Astrometry | |
| Radial velocity (Rv) | −10.4±0.7 km/s |
| Proper motion (μ) | RA: +107.99 mas/yr Dec.: + 27.15 mas/yr |
| Parallax (π) | 41.99 ± 0.16 mas |
| Distance | 77.7 ± 0.3 ly (23.82 ± 0.09 pc) |
| Details | |
| 23 UMa A | |
| Mass | 1.862 M☉ |
| Radius | 2.90±0.03 R☉ |
| Luminosity | 14.8±0.1 L☉ |
| Temperature | 6,651±27 K |
| Metallicity [Fe/H] | 0.17 dex |
| Age | 1.3 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The primary component is a yellow-white F-type subgiant with an apparent magnitude of +3.65. It has 1.9 times the Sun's mass, 2.9 times the Sun's radius and is emitting 15 times the luminosity of the Sun at an effective temperature of 6,651 K. Orbiting at an angular separation of 22.7 arcseconds is the 9th magnitude secondary companion. There is a magnitude +10.5 optical companion at an angular separation of 99.6 arcseconds.