Alpha Centauri is a star.
Alpha Centauri . It consists of three stars : the double star Alpha Centauri A ( also named Rigil Kentaurus ) and Alpha Centauri B together with a small and faint red dwarf , Alpha Centauri C ( also named Proxima Centauri ) , that may be gravitationally bound to the other two . Alpha Centauri A ( α Cen A ) has 1.1 times the mass and 1.519 times the luminosity of the Sun , while Alpha Centauri B ( α Cen B ) is smaller and cooler , at 0.907 times the Sun 's mass and 0.445 times its visual luminosity .