Alpha Centauri system
The planet Alpha Centauri Five was located in the Alpha Centauri system, (PROSE: Lucifer Rising) as was the planet Glox, part of the Gloxxian Empire, which included the Alpha Centauri system, and many more besides. (AUDIO: I Am The Master)
Wayne Bland II (in Panda's body) once suggest that he and Iris Wildthyme lie to Kragoom that there was a planetoid in the Alpha Centauri system that fancied him. (AUDIO: The Iris Wildthyme Appreciation Society)
The Battle of Alpha Centauri took place during the Second Dalek War in the 26th century. A squadron of Silurian vessels drove off the main Dalek force. (PROSE: Love and War)
During the Cyberon War, the Earth Alliance had an "Alpha Centauri base". (AUDIO: Curse of the Cyberons)