Alcor
Definition
Alcor is a star in the constellation Ursa Major, often associated with Mizar as part of a visual double star system. It is located approximately 81 light-years from Earth and is visible to the naked eye.
5 Must Know Facts For Your Next Test
- Alcor and Mizar form a visual double star, meaning they appear close together in the sky but are not necessarily gravitationally bound.
- Alcor has an apparent magnitude of about 4.0, making it moderately bright and visible without telescopes.
- The Alcor-Mizar pair has been historically used as a test of eyesight.
- Alcor is classified as an A5V type star, indicating it is a main-sequence star with a surface temperature around 8,000 Kelvin.
- Recent studies suggest that Alcor may have its own companion star, making it part of a more complex multiple-star system.
Review Questions
- What type of star is Alcor classified as?
- How far is Alcor from Earth?
- What historical use did the Alcor-Mizar pair have?
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Related terms
Mizar: A nearby star to Alcor and part of the visual double; it is also in Ursa Major.
Visual Double Star: Two stars that appear close together in the sky but are not necessarily gravitationally bound.
Main-Sequence Star: A star that is in the longest-lasting stage of its life cycle, where it fuses hydrogen into helium in its core.
