page_title: Alcor (star)
section_title: Mizar and Alcor
hierarchical_section_title: Alcor (star) / Mizar and Alcor
caption_attribution_description: English: Author: Shawn E. Gano, http://www.nd.edu/~sgano/astronomy/diagrams/dipper.jpgNederlands: Sterrenbeeld "De grote beer", foto Shawn E. Gano.
context_page_description: Alcor is a binary star system in the constellation of Ursa Major. It is the fainter companion of Mizar, the two stars forming a naked eye double in the handle of the Big Dipper asterism in the constellation of Ursa Major. The two both lie about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite.
context_section_description: With normal eyesight Alcor appears at about 12 minutes of arc from the second-magnitude star Mizar.  Alcor is of magnitude 3.99 and spectral class A5V.
  Mizar and Alcor's proper motions show they move together, along with most of the other stars of the Big Dipper except Dubhe and Alkaid, as members of the Ursa Major Moving Group, a mostly dispersed group of stars sharing a common birth. However, it has yet to be demonstrated conclusively that they are gravitationally bound. Recent studies indicate that Alcor and Mizar are somewhat closer together than previously thought: approximately 74,000 ± 39,000 AU or 0.5–1.5 light years. The uncertainty is due to our uncertainty about the exact distances from us. If they are exactly the same distance from us (somewhat unlikely) then the distance between them is only 17800 AU (0.281 ly).
caption: Mizar and Alcor in constellation Ursa Major
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