Alpha Ursae Majoris


Distance (Light Years) 123.6 ± 2.5
Apparent Magnitude 1.81
Color (B-V)1.07

Names For This Star

The name Dubhe derives from the Arabic phrase Thahr al Dubb al Akbar meaning "The Back of the Greater Bear".

Description of the Star

Dubhe is an orange K0IIIa giant. The spectral type implies an effective temperature of 4500 K, a mass 4 times that of the sun and 16 times the diameter.

Dubhe's Companion

Dubhe has a companion, Dubhe B, separated by 0.672 sec of arc corresponding to a projected distance of 25 AU. The companion appears to be a yellowish F0V main sequence star of about 7400 K temperature, with a mass 1.7 times that of the sun and with 1.3 times the diameter. The Apparent Magnitude of the companion is about 4.73.

The combined luminosity of Dubhe and its companion is about 230 times that of the sun.

Dubhe C

There is a third star apparently physically associated with the Dubhe system. Dubhe C is an F8 star of Apparent Magnitude 7.12 separated by 280 sec of arc from Dubhe A. This corresponds to a projected distance of about 11,000 AU or 0.17 ly.

The spectrum of Dubhe C indicates that it has itself a near companion that in a 6.4 day orbit.

Other Designations For This Star


50 Ursae Majoris

Hipparcos Identifier (HIP Number)


Harvard Revised (HR Number)


Henry Draper Catalog (HD Number)


Bonner Durchmusterung (BD Number)

BD+62 1161
Smithsonian Astrophysical
Observatory compendium (SAO Number)

Fundamental Katalog (FK5 Number)



Copyright © 1998 - 2010 by Arnold V. Lesikar,
Professor Emeritus
Dept. of Physics, Astronomy, and Engineering Science,
St. Cloud State University,St. Cloud, MN 56301-4498

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