Its proper name is Rigil Kentaurus ( often shortened to Rigil Kent ) , which comes from the Arabic phrase Al Rijl al Kentaurus , meaning `` foot of the centaur '' , but is usually referred to by its Bayer name Alpha Centauri . This prominent southern star commonly bears the proper name Rigil Kentaurus ( often shortened to Rigil Kent , former Rigjl Kentaurus ; Riguel Kentaurus in Portuguese ) , derived from the Arabic phrase Rijl QantÅ `` ris ( or Rijl al-Qant Å `` ris , meaning `` Foot of the Centaur ) '' , but is most often referred to by its Bayer designation Alpha Centauri .