Euphrosyne is a rusty, highly isolated planet with a toxic but breathable atmosphere. Euphrosyne is about 10k km in diameter but its denser than earth so gravity is about the same as on earth.
Following the devastating nuclear bombardment of The Great War, Euphrosyne was left completely covered in a dense fugue and orbital debris field. This field entirely isolates the planet, preventing any spacecraft from leaving or entering.
The system star is called Aife.