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 PROSE: Return of the Living Dad and PROSE: 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''.