What kind of star is Dubhe?
Dubhe, catalogued as Alpha Ursae Majoris A (α UMa A), appears in the official constellation Ursa Major. Its apparent visual magnitude is about 1.81 combined, while its estimated distance is about 123 light-years. Astronomers classify the object as K0 III giant with F-type companion. These labels describe temperature, luminosity class or system components; they should not be read as a claim that every naked-eye point is a single isolated star.
The visible primary is an evolved K-type giant that has exhausted hydrogen in its core and expanded to many times the Sun’s radius. Spectroscopy and orbital work reveal a much fainter F-type stellar companion in a long-period orbit of several decades. Dubhe’s distance and velocity distinguish it from the co-moving group that includes Merak, Phecda, Megrez, Alioth and Mizar. This matters physically: the familiar Dipper is a perspective pattern containing both related and unrelated stars, not a bound cluster. Its contrasting colour against the group’s A-type stars makes the difference perceptible.
The coordinate pair RA 11h 03m 43.67s, Dec +61° 45′ 03.7″ fixes the object's direction on the celestial sphere for the J2000 reference epoch. Right ascension works like celestial longitude measured in hours, while declination works like latitude north or south of the celestial equator. Proper motion and improved measurements can refine catalogue positions, but these coordinates are sufficiently precise for a finder chart or planetarium search.
Dubhe data at a glance
| Proper name | Dubhe | Catalogue designation | Alpha Ursae Majoris A (α UMa A) |
|---|---|---|---|
| Constellation | Ursa Major | Apparent magnitude | about 1.81 combined |
| Spectral or system type | K0 III giant with F-type companion | Estimated distance | about 123 light-years |
| Right ascension (J2000) | 11h 03m 43.67s | Declination (J2000) | +61° 45′ 03.7″ |
Values are rounded for an observer-friendly overview. Consult the linked SIMBAD record for component-level identifiers, bibliography, measurement provenance and newer catalogue values.
The name Dubhe
Dubhe comes from Arabic ẓahr al-dubb al-akbar, “the back of the greater bear.” It marks the upper outer corner of the Big Dipper’s bowl.
Arabic star lore described portions of the Great Bear with anatomical terms, and the word for the bear’s back reached European catalogues as Dubhe. Navigators and popular astronomy later emphasized Dubhe with Merak as the Pointers. The pair’s role is geometrical rather than physical. The IAU Working Group on Star Names assigned Dubhe to Alpha Ursae Majoris A, avoiding ambiguity with its companion.
Modern professional catalogues retain identifiers such as the Bayer designation alongside a proper name. The International Astronomical Union standardizes which name belongs to which component—an important distinction for systems whose combined light looks like one star from Earth.
How to find Dubhe
Find the Big Dipper’s bowl and identify its two stars farthest from the handle. Dubhe is the upper, warmer-coloured pointer. Extend a line from Merak through Dubhe to Polaris. The physical companion is too close and unequal for a routine small-telescope split.
Circumpolar across much of northern Europe and North America; visible seasonally down to low southern latitudes. Visibility on a particular night still depends on latitude, season, time, horizon obstructions, weather and local light pollution. Use the interactive atlas below to check the surrounding field before observing.
Observation checklist
- Identify the two bowl stars opposite the handle; Dubhe is the northern one.
- Extend Merak-to-Dubhe about five times to find Polaris.
- Compare Dubhe’s yellow-orange tint with whiter Merak and Phecda.
- At high northern latitudes, observe its full daily circle without setting.
Interesting facts about Dubhe
- Dubhe is one of the two famous Pointer Stars used to locate Polaris.
- Its primary is an orange K giant with a fainter stellar companion.
- Dubhe is not a member of the Ursa Major Moving Group.
- It is the second-brightest star in Ursa Major after Alioth.
- The IAU proper name belongs specifically to component A.
Continue from Dubhe into the night sky
Use the Ursa Major constellation guide to place this star within its larger pattern. When you are ready to observe, compare dark-sky places, find a nearby observatory, or follow our practical guide to finding a star in the night sky. Symbolically registered names are kept separately in the searchable Star-Register catalogue.
Sources and further reading
Measurements are rounded for readability. Multiple systems, variable stars and distant supergiants can have component-specific or model-dependent values. Survey panels show photographic sky fields, not the physical surface of the star.