What kind of star is Phecda?
Phecda, catalogued as Gamma Ursae Majoris Aa (γ UMa Aa), appears in the official constellation Ursa Major. Its apparent visual magnitude is about 2.41, while its estimated distance is about 83 light-years. Astronomers classify the object as A0 Ve main-sequence star. 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.
Phecda is a hydrogen-burning A-type star with spectral emission features indicated by the “e” suffix in some classifications. It lies at nearly the same distance as several other central Dipper stars and shares their velocity through space, membership evidence stronger than simple alignment on the sky. The Ursa Major group formed together hundreds of millions of years ago and has since spread over a broad region. Phecda has reported close and optical companions, but catalogues distinguish gravitational components from unrelated field stars; the official proper name applies to Aa rather than automatically naming every listed neighbour.
The coordinate pair RA 11h 53m 49.84s, Dec +53° 41′ 41.1″ 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.
Phecda data at a glance
| Proper name | Phecda | Catalogue designation | Gamma Ursae Majoris Aa (γ UMa Aa) |
|---|---|---|---|
| Constellation | Ursa Major | Apparent magnitude | about 2.41 |
| Spectral or system type | A0 Ve main-sequence star | Estimated distance | about 83 light-years |
| Right ascension (J2000) | 11h 53m 49.84s | Declination (J2000) | +53° 41′ 41.1″ |
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 Phecda
Phecda comes from Arabic fakhdh al-dubb, “the thigh of the bear.” Phad is an older spelling; the IAU standardized Phecda for component Aa.
Its traditional Arabic name mapped the star onto the Great Bear’s thigh. The spelling moved through forms including Phad before modern standardization. Bayer designated it Gamma Ursae Majoris, yet brightness ranking across Ursa Major is not a simple Alpha-to-Omega sequence. Proper-motion studies later revealed that Phecda’s relation to several Dipper stars is physical, adding a modern stellar-family story to the older bear figure.
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 Phecda
Phecda is the lower inner bowl star where the Dipper’s base meets the side nearest the handle. A diagonal across the bowl from Dubhe reaches it. Its white colour is evident beside orange Dubhe, while optical companions need magnification and should not be assumed physically bound.
Circumpolar from much of the Northern Hemisphere and best placed in the evening during northern spring. 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
- Locate the bottom of the Dipper’s bowl; Phecda is the corner closer to the handle.
- Compare its white light with orange Dubhe at the opposite upper corner.
- Trace Phecda toward Megrez to find the bowl’s inner wall.
- Treat faint nearby points cautiously: a star in the same eyepiece is not necessarily a bound companion.
Interesting facts about Phecda
- Phecda is a member of the Ursa Major Moving Group.
- It is hotter and more massive than the Sun but still burns hydrogen in its core.
- The IAU assigns the name to component Aa.
- Its alternate historical spelling Phad remains common in older atlases.
- Phecda marks the Great Bear’s thigh in the name’s original anatomical scheme.
Continue from Phecda 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.