Alpha Ursae Majoris

light-years
Proper names: Dubhe, Alpha Ursae Majoris, Dubb, Dubh, Thahr al Dubb al Akbar, The Back of the Great Bear, 50 Ursae Majoris
Catalog numbers:
     Hoffleit Bright Star (HR) 4301, Henry Draper (HD) 95689, Bonner Durchmusterung (BD) +62°1161, Smithsonian Astrophysical Observatory (SAO) 15384, Fifth Fundamental Catalogue (FK5) 417, Aitken Double Star (ADS) 8035, New Suspected Variable (NSV) 5070, S.W. Burnham (BU) 1077, Hipparcos Input Catalog (HIC) 54061, AGK3 Reference (AGK3R) +62°691, Caltech 2-microns Survey (IRC) +60208
Heavy element abundance: 64% of Sol
Source for heavy element abundance: Strobel [Fe/H] Determinations
Arity: binary
Right Ascension and Declination: 11h3m43.666s, +61°45'3.22" (epoch 2000.0)
Distance from Sol: 124 light-years (37.9 parsecs)
Standard error in distance: 2%
Source for distance: Hipparcos
Celestial (X,Y,Z) coordinates in ly: -56.8, 14.2, 109
Galactic (X,Y,Z) coordinates in ly: -61.3, 46.7, 96.7
Proper motion: 0.136 arcsec/yr (241.0° from north)
Radial Velocity: -8.9 km/sec
Source for proper motion: Fifth Fundamental Catalogue
Source for radial velocity: GCRV (Wilson 1953)
Galactic (U,V,W) velocity components in km/s: -12.9, -20.5, -9.65

What do all these fields mean?

Data for A and B's orbit around one other:
Combined absolute visual magnitude: -1.10
Combined visual luminosity: 239 x Sol
Period: 44.4 years
Semimajor Axis: 22.9 A.U.s
Eccentricity: 0.4
Periastron distance: 13.7 A.U.s
Apastron distance: 32.0 A.U.s
Year in which periastron occurs: 1956.8
Source for orbit data: Scholz, McCaughrean, Lodieu, and Kuhlbrodt (2003)
As seen from A:
     At periastron, B would appear as magnitude -23.97
     At apastron, B would appear as magnitude -22.13
As seen from B:
     At periastron, A would appear as magnitude -26.91
     At apastron, A would appear as magnitude -25.07


Component A:
Spectral class: K0
Luminosity Class: IIIa
Apparent visual magnitude: +1.87
Absolute visual magnitude: -1.02
Visual luminosity: 224 x Sol
Color indices: B-V= +1.07, U-B= +0.92, R-I= +0.58
Diameter: 30.4 x Sol
Source for diameter: Apparent Diameters and Absolute Radii of Stars (Fracassini+ 1988)
Comfort Zone (visual): 15.0 A.U.s
Angular size of star in sky in CZ: 1.083438 degrees


Component B:
Spectral class: F7
Luminosity Class: V
Apparent visual magnitude: +4.81
Absolute visual magnitude: +1.92
Visual luminosity: 14.9 x Sol
Comfort Zone (visual): 3.86 A.U.s

light-years
but not more than light-years away
Data for this star system were most recently updated on 6-October-2001.