Supernova
From FreeSpace Wiki
The Supernova appears in the Final level of FreeSpace 2, named Apocalypse, which is shown towards the end of the game and inside a cutscene. However, it is possible to stop the Supernova by disabling the Melchom and the Bane since it is triggered by their departure or destruction.
Also not to be confused with the multiplayer pilot, Supernova.