alpha canis majoris

from The Collaborative International Dictionary of English v.0.48

Dog Star \Dog" Star`\
   Sirius, a star of the constellation Canis Major, or the
   Greater Dog, and the brightest star in the heavens; -- called
   also {Canicula}, and, in astronomical charts, {[alpha] Canis
   Majoris}. See {Dog days}.
   [1913 Webster]