Beta Centauri

star system in the southern constellation of Centaurus

Beta Centauri (β Centauri, β Cen, Agena, or Hadar), is a triple star system in the southern constellation of Centaurus.

Night sky position

The system's combined apparent visual magnitude of 0.61 makes it the second-brightest star in Centaurus and one of the brightest stars in the night sky.[1] According to parallax measurements from the astrometric Hipparcos satellite, the distance to this system is about 390 ± 20 light-years (120 ± 6 parsecs).

Beta Centauri is well known in the Southern Hemisphere. A line made from Alpha Centauri, through Beta Centauri leads to within a few degrees of Gacrux, the star at the top of the Southern Cross. Using Gacrux, a navigator can draw a line with Acrux at the bottom to find South.[2]


  1. Hoffleit, Dorrit; Jaschek, Carlos 1991. The Bright star catalogue. New Haven: Yale University Observatory, 5th rev. ed.
  2. Kyselka, Will & Lanterman, Ray E. 1976. North Star to Southern Cross. Honolulu : University Press of Hawaii. University of Hawaii Press, p. 59.