Bright & Nearby Stars · Constellation Ursa Major

Dubhe (Alpha Ursae Majoris)

Coordinates, Hipparcos distance (123 ly), magnitude 1.79, 44.4-year K0 III + F0 V binary orbit, and northern pointer guide for Dubhe.

Right Ascension (J2000.0)11h 03m 43.67s
Declination (J2000.0)+61° 45′ 03.7″
Primary ClassificationK-type red-clump giant in a hierarchical quadruple system
Best Observing SeasonSpring (February–July; circumpolar north of +28°N)

Provenance-Backed Scientific Measurements

Every measurement below preserves its unit, uncertainty interval, observational method, reference epoch, quality status, and primary catalog source. See Uncertainty & Provenance for how competing measurements are handled.

Astrometric, Photometric, and Physical Parameters for Dubhe (Alpha Ursae Majoris)
ParameterValueUncertaintyMethod & EpochQuality StatusSource Archive
Combined apparent visual magnitude (V)1.79 mag± 0.01 magJohnson UBV photometry (Dubhe A = 1.87 mag, Dubhe B = 4.81 mag)definitiveHipparcos New Reduction Catalog
Trigonometric parallax26.54 mas± 0.48 masHipparcos New Reduction astrometric solution (37.68 ± 0.68 pc) (J2000.0)definitiveHipparcos New Reduction Catalog
Distance in light-years122.9 ly± 2.2 lyDerived from Hipparcos parallax 26.54 ± 0.48 masdefinitiveHipparcos New Reduction Catalog
Visual binary orbital period (Dubhe A–B)16235 d± 35 dAstrometric & spectroscopic binary orbit (44.45 ± 0.10 Julian years)definitiveSIMBAD Astronomical Database (CDS)
Primary giant mass (Dubhe A)4.25 M☉± 0.25 M☉44.45-year binary orbit + asteroseismology (Dubhe B = 1.7 ± 0.1 M☉)high-confidenceSIMBAD Astronomical Database (CDS)
Measurement Uncertainties & Competing Solutions: Because Dubhe A and B orbit at an angular separation of only 0.3″ to 0.8″ over their 44.45-year cycle, Hipparcos had to solve simultaneously for the photocenter orbit and the annual parallax (26.54 ± 0.48 mas).

J2000 Equatorial Sky Chart & Culmination Altitude

The chart below plots Dubhe (Alpha Ursae Majoris Giant Binary) at RA 11h 03m 43.67s, Dec +61° 45′ 03.7″ within Ursa Major, alongside peak meridian transit altitudes for 40°N and 30°S observers. Use the RA/Dec Coordinate Converter to compute exact culmination altitude for your latitude.

J2000 Equatorial Sky Position (Ursa Major) +90° 0° −90° 24h 12h RA 0h Peak Meridian Altitude 68° 40°N Lat 0° 30°S Lat RA: 11h 03m 43.67s Dec: +61° 45′ 03.7″ Epoch: J2000.0 · V = 1.79 mag First-party vector diagram derived from IAU / CDS SIMBAD / Gaia DR3 astrometry.

Astrophysical Context & Structure

Dubhe (Alpha Ursae Majoris, from the Arabic al-Dubb meaning 'the Bear') marks the upper-outer (northwestern) lip of the Big Dipper's bowl and is the second-brightest star in Ursa Major at apparent visual magnitude 1.79. Paired with 2.37-magnitude Merak (Beta Ursae Majoris) 5.4° to its south, Dubhe forms the famous 'Pointers': a line drawn northward from Merak through Dubhe leads the eye 28° straight to Polaris, the North Star.

While the five inner stars of the Big Dipper (Merak, Phecda, Megrez, Alioth, and Mizar) all travel together through space at ~80–83 light-years as the Ursa Major Moving Group, Dubhe (along with Alkaid at the end of the handle) is an unrelated background intruder: located 37.68 ± 0.68 parsecs (122.9 light-years) away, Dubhe moves in the opposite direction across the sky, meaning the familiar Dipper shape will gradually deform over the next 50,000 years.

Astrophysically, Dubhe is a hierarchical quadruple system led by Dubhe A, an evolved K0 III orange-gold red-clump giant (4.25 solar masses, ~17 solar radii, 316 solar luminosities, 4,660 K) fusing helium in its core, orbited every 44.45 years at a mean separation of 23 AU (~0.6 arcseconds) by Dubhe B, a 4.8-magnitude F0 V main-sequence star. Twenty-three arcseconds (~8,000 AU) away orbits a 7th-magnitude spectroscopic binary, Dubhe C (HD 95638).

Practical Visual Observing Guide

Minimum InstrumentNaked eye (200 mm+ telescope at 300×+ for tight 0.6″ binary split)
Recommended MagnificationNaked eye / binoculars (300×+ for Dubhe AB)
Best Evening SeasonSpring (February–July; circumpolar north of +28°N)
  • Look carefully at the Big Dipper with the naked eye or binoculars: Dubhe is noticeably warm golden-orange (4,660 K), standing out immediately against the six pure blue-white A- and B-type stars that make up the rest of the Dipper.
  • Splitting 4.8-magnitude Dubhe B from 1.9-magnitude Dubhe A at 0.6–0.7 arcseconds separation requires a 200–250 mm telescope at 300×+ under steady seeing, whereas 7.1-magnitude companion HD 95638 (3.5 arcminutes west) is effortless in binoculars.

Catalog Cross-Identifications & Aliases

Common Aliases: α Ursae Majoris · HD 95689 · HIP 54061 · 50 Ursae Majoris

Cross-Catalog Identifiers for Dubhe (Alpha Ursae Majoris)
Catalog AuthorityIdentifier
HIPHIP 54061
HDHD 95689
SIMBAD* alf UMa
WIKIDATAQ13051
Related Object · Ursa Major

Alioth (Epsilon Ursae Majoris Ap Variable)

Coordinates, Hipparcos distance (82.6 ly), magnitude 1.77, Alpha2 CVn magnetic chromium spots, and observing guide for Alioth in Ursa Major.

Related Object · Ursa Major

Mizar & Alcor (Zeta Ursae Majoris System)

Coordinates, Hipparcos/VLBI distance (82.8 ly), 11.8′ naked-eye pair, 14.4″ Mizar A–B split, and observing guide for Mizar & Alcor.

Reference Guide

Proper Motion, Radial Velocity & Redshift

How astronomers combine tangential proper motion (mas/yr), Doppler radial velocity (km/s), and cosmological redshift (z) to reconstruct 3D space motion.

Reference Guide

Stellar Spectral Classification (OBAFGKM)

Reference guide to Morgan-Keenan (MK) stellar classification (O B A F G K M), luminosity classes (I–V, WD), color index (B-V), and the H-R diagram.

Scientific Sources & Dataset Provenance