Bellatrix

Bellatrix was a double star system located in the Orion constellation, roughly 324 light years away from Earth. It was composed of a white dwarf and a companion star. Material had been siphoned off the companion star into the white dwarf until it went nova in 1644. The Sentience fed on the energy of the nova. (PROSE: Nightshade)

Battle against the Daleks
Bellatrix space saw a pitched battle in the mid-26th century, in which Dalek forces routed Spacefleet. The Tisiphone, a Fury-class Spacefleet fighter under the command of Admiral Isaac Summerfield II, vanished at the end of the battle; her crew were presumed deserters. The Clotho, under command of Captain Sarah Groenewegen, was the only ship that survived the battle. (PROSE: Return of the Living Dad)

Behind the scenes
The exact date of the Battle of Bellatrix is difficult to ascertain. While in the novels Return of the Living Dad and Dead Romance it is given as 2543, Bernice Summerfield, born in 2540, would only have been a toddler, whereas she repeatedly and specifically says that she was seven at the time of her father's disappearance (PROSE: Love and War, et. al.) She also says that she was eight when she lost her mother (AUDIO: The Extinction Event), an event that took place less than six months after her father's disappearance. (PROSE: The Evacuation of Bernice Summerfield Considered as a Short Film by Terry Gilliam) The battle therefore must have been fought some time between 21 December 2547 and 20 June 2548''.