I just entered a new system and found an 8000 ton wreck. The salvage ship didn't recover any parts. No other signs of anything in the system. I kinda think this might be the Precursors, but I thought they'd have some installations somewhere.
It's also possible I guess that it's an NPR wreck, but as I said, that's the only sign of life I've seen this game that wasn't the star swarm.
So do precursors or NPR's just leave random wrecks lying around?