| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 09h 31m 31.70873s [1] |
| Declination | +63° 03′ 42.7013″ [1] |
| Apparent magnitude (V) | +3.65 [2] / +9.0 |
| Characteristics | |
| Spectral type | F0IV [3] |
| B−V color index | 0.360±0.015 [2] |
| Astrometry | |
| Radial velocity (Rv) | −10.4±0.7 [2] km/s |
| Proper motion (μ) | RA: +107.99 [1] mas/yr Dec.: + 27.15 [1] mas/yr |
| Parallax (π) | 41.99±0.16 mas [1] |
| Distance | 77.7 ± 0.3 ly (23.82 ± 0.09 pc) |
| Details | |
| 23 UMa A | |
| Mass | 1.862 [3] M☉ |
| Radius | 2.90±0.03 [3] R☉ |
| Luminosity | 14.8±0.1 [3] L☉ |
| Temperature | 6,651±27 [3] K |
| Metallicity [Fe/H] | 0.17 [3] dex |
| Age | 1.3 [3] Gyr |
| Other designations | |
| h UMa, 23 UMa, BD+63°845, FK5 355, GJ 3534, HD 81937, HIP 46733, HR 3757, SAO 14908, CCDM J09315+6303A/B [4] | |
| Database references | |
| SIMBAD | data |
23 Ursae Majoris, or 23 UMa, is a binary star system in the constellation Ursa Major, [4] located is approximately 77.7 light years from the Sun. [1] 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. [2] It is moving closer to the Earth with a heliocentric radial velocity of −10 km/s. [2]
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 [5] at an effective temperature of 6,651 K. [3] 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.
With τ, υ, φ, θ, e and f, it composed the Arabic asterism Sarīr Banāt al-Na'sh, the Throne of the daughters of Na'sh, and Al-Haud, the Pond. [6] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al-Haud was the title for seven stars : f as Alhaud I, τ as Alhaud II, e as Alhaud III, this star (h) as Alhaud IV, θ as Alhaud V, υ as Alhaud VI and φ as Alhaud VII . [7]