Leboon

 was a star in the Leboontic constellation. 47 planets orbited it, which eventually became 46, when, according to the Fifth Doctor, "there was a war with the Cybermen". The Doctor had friends in that system. While he was on a ship headed for a collision course with Leboon, then in the red giant stage, the Fifth Doctor waved to the star system's worlds, unsure if he had met the friends he made there yet at that point in history. (AUDIO: The Judgement of Isskar)