A simple explanation that star charts were created long before we could travel to the actual stars and stars were name when those maps were created.Question: If they've been drifting on slow drives, how did they suddenly appear near a planet?
And, if they've been isolated from outside contact, how do they know a current system name?
alternatively this this a Thargoid trap and they have use this captured generation ship create a super virus that will wipe us all out!