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Alpha Centauri (α Centauri / α Cen); (also known as Rigil Kentaurus, Rigil Kent, or Toliman) is the binary star system Alpha Centauri AB (α Cen AB), of which Alpha Centauri A (α Cen A) is the brightest star in the southern constellation of Centaurus. To the unaided eye it appears as a single star, whose total visual magnitude would identify it as the third brightest star in the night sky.

Alpha Centauri AB is 1.34 parsec or 4.37 light years away from our Sun. The two stars are the closest stars to the Sun after their companion Proxima Centauri, at 0.21 light-year away from the two, and at 4.243 light-years away from the Sun.

At −0.27v visual magnitude, Alpha Centauri appears to the naked-eye as a single star and is fainter than Sirius and Canopus. The next brightest star in the night sky is Arcturus. When considered among the individual brightest stars in the sky (excluding the Sun), Alpha Centauri A is the fourth brightest at −0.01 magnitude being only fractionally fainter than Arcturus at −0.04v magnitude. Alpha Centauri B at 1.33v magnitude is twenty-first in brightness.

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