I'm using the setting from Coriolis as a sector. I'll adapt the Coriolis adventures I already have and know.
The idea: A colony ship, from the Empire, en route to an unexplored sector, was diverted from its destination by the sudden opening of a wormhole. The colony ship couldn't avert it. The wormhole disappeared once the ship was on the other side. The colonists were cut off from the Empire and don't know where they are.
Fast forward 300 years later. The colonists have the space station Coriolis, created from the colony ship, and a major city on the nearby planet Kua. PCs will probably be explorers from what I can tell. The system contains 32 planets plus moons. The sector is mostly unexplored. The regions that are explored only have minor colonies, industrial plants extra resources, etc. Artifacts of ancient alien civilizations abound. Some are extremely dangerous if tampered with.
A question remains. Was the wormhole deliberately placed on their path? If yes by whom?