CENTAURUS (" T11 CENTAUR ")  , in astronomy, a constellation of the southern hemisphere, mentioned by Eudoxus (4th century B.C.) and Aratus (3rd century B.C.), Ptolemy catalogued thirty-seven stars in it. a-Centauri is a splendid binary star . Its components are of the 1st magnitude, and revolve in a period of eighty-one years; and since its parallax is 0'75", it is the nearest star to the earth; w-Centauri, the finest globular star-cluster in the heavens, consists of about 6000 stars in a space of about 20' diameter, of which about 125 variables have been examined . Nova Centauri, a " new " star, was discovered in 1895 by Mrs Fleming in photographs taken at Harvard .