23 Ursae Majoris

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]

23 Ursae Majoris

Location of 23 Ursae Majoris (circled)
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

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.

Nomenclature

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]