Dubhe vs Merak

Property Dubhe Merak
Désignation 50Alp UMa 48Bet UMa
Constellation Ursa Major Ursa Major
Classe Spectrale Class F — F-type (Yellow-White) Class A — A-type (White)
Magnitude Apparente +1.81 +2.34
Magnitude Absolue -1.07 0.40
Distance 123 ly 79.7 ly
Masse N/A N/A
Rayon N/A N/A
Température N/A N/A
Luminosité N/A N/A

Key Differences

  • Both form the famous 'pointer stars' of the Big Dipper — drawing a line through them leads to Polaris.
  • Dubhe is a K-type giant at ~123 light-years; Merak is an A-type main-sequence star at ~80 light-years.
  • Merak is a member of the Ursa Major Moving Group and hosts a debris disk; Dubhe is not a member and moves separately.
  • Dubhe has a radius of ~30 R☉, having evolved off the main sequence; Merak remains on the main sequence at ~3 R☉.
  • Despite their pairing in navigation lore, the two stars are at quite different distances and unrelated physically.

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