Alpha-centauri-a Definition

pronoun

(astronomy) The brightest star in the southern constellation of Centaurus. Alpha Centauri is actually a binary star with Alpha Centauri C or Proxima Centauri as a third component. Alpha Centauri A is the brightest star of the system and is somewhat brighter than our sun. Alpha Centauri B is somewhat fainter than Alpha Centauri A but much brighter than Proxima Centauri.

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