- Alpha Ursae Majoris
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Alpha Ursae Majoris A/B/C 
Stars of Ursa Major, including DubheObservation data
Epoch J2000 Equinox J2000Constellation Ursa Major Right ascension 11h 03m 43.7s Declination +61° 45′ 03″ Apparent magnitude (V) 1.79 (1.87/4.81/7.12) Characteristics Spectral type K0 III / F0 V / F8 U−B color index 0.92 B−V color index 1.07 Variable type Pulsating Astrometry Radial velocity (Rv) −9 km/s Proper motion (μ) RA: −136.46 mas/yr
Dec.: −35.25 mas/yrParallax (π) 26.38 ± 0.53 mas Distance 124 ± 2 ly
(37.9 ± 0.8 pc)Absolute magnitude (MV) −1.09/1.83/4.22 Orbit Companion α UMa B Period (P) 44.4 yr Semimajor axis (a) 0.603" Eccentricity (e) 0.4 Inclination (i) 152° Longitude of the node (Ω) 2000° Periastron epoch (T) 1956.8 Details Mass 4/1.7 M☉ Radius 30/1.3 R☉ Luminosity 300 L☉ Temperature 4,500/7,400 K Metallicity ? Rotation <17 km/s. Age ? years Other designations Database references SIMBAD data Alpha Ursae Majoris (α UMa, α Ursae Majoris) is the second-brightest star in the constellation of Ursa Major (despite its Bayer designation of "alpha"). It has the traditional name Dubhe, and a rarer name Ak.
It forms part of the Big Dipper (also known as the Plough or the Great Bear), and is the northern of the 'pointers' (or 'guards'), the two stars of Ursa Major which point towards Polaris, the North Star. Dubhe is about 124 light years away and is typical of a red giant, an evolved helium-burning star. It is also a multiple star, orbited by a main sequence companion, Dubhe B, at a distance of about 23 astronomical units (AU), as well as a close pair, Dubhe C, at a distance of about 8000 AU.
However, it is not part of the Ursa Major Moving Group.
The traditional name comes from the Arabic for "bear", dubb, from the phrase ظهر الدب الاكبر żahr ad-dubb al-akbar "the back of the Greater Bear".
It is known as 北斗一 (the First Star of the Northern Dipper) or 天樞 (the Celestial Pivot) in Chinese.
Dubhe is the official state star of the State of Utah.
Dubhe in Military
USS Dubhe (ID-2562) is once of United States navy ship.
Stars of Ursa Major Bayer α (Dubhe) • β (Merak) • γ (Phecda) • δ (Megrez) • ε (Alioth) • ζ (Mizar) • η (Alkaid) • θ (Alhaud) • ι (Talitha Bor) • κ (Talitha Aus) • λ (Tania Bor) • μ (Tania Aus) • ν (Alula Bor) • ξ (Alula Aus) • ο (Muscida) • π¹ • π² • ρ • σ¹ • σ² • τ • υ • φ • χ • ψ • ω • b • c • d • e • f • g (Alcor) • h • AFlamsteed 1 (ο, Muscida) • 2 (A) • 3 (π¹) • 4 (π²) • 5 (b) • 6 • 7 • 8 (ρ) • 9 (ι, Talitha Bor) • 11 (σ¹) • 12 (κ, Talitha Aus) • 13 (σ²) • 14 (τ) • 15 (f) • 16 (c) • 17 • 18 (e) • 19 • 20 • 21 • 22 • 23 (h) • 24 (d) • 25 (θ, Alhaud) • 26 • 27 • 28 • 29 (υ) • 30 (φ) • 31 • 32 • 33 (λ, Tania Bor) • 34 (μ, Tania Aus) • 35 • 36 • 37 • 38 • 39 • 40 • 41 • 42 • 43 • 44 • 45 (ω) • 46 • 47 • 48 (β, Merak) • 49 • 50 (α, Dubhe) • 51 • 52 (ψ) • 53 (ξ, Alula Aus) • 54 (ν, Alula Bor) • 55 • 56 • 57 • 58 • 59 • 60 • 61 • 62 • 63 (χ) • 64 (γ, Phecda) • 65 • 66 • 67 • 68 • 69 (δ, Megrez) • 70 • 71 • 72 • 73 • 74 • 75 • 76 • 77 (ε, Alioth) • 78 • 79 (ζ, Mizar) • 80 (g, Alcor) • 81 • 82 • 83 • 84 • 85 (η, Alkaid) • 86 • 55 Cam • 56 Cam • 57 Cam • 1 CVn • 14 LMi • 15 LMi • 47 LMi • 37 Lyn • 41 Lyn • 44 LynNearby Lalande 21185 • WISE 1405+5534 • Gliese 412 • Groombridge 1618 • Gliese 338 • GJ 1151 • ξ (Alula Aus) • Gliese 450 • Gliese 424 • Groombridge 1830Other R • S • W • Winnecke 4List Categories:- Multiple star stubs
- Bayer objects
- Double stars
- K-type giants
- Triple star systems
- Ursa Major constellation
- F-type main sequence stars
- Stars with proper names
- Symbols of Utah
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