[The Colonel]

Originally Posted by Fred Brackin

Eh, this one depends on how high the Science! dials have been set.

https://en.wikipedia.org/wiki/Crab_Nebula

......is all about the Crab Nebula which is certainly our most studied supernova remnant.

I seem to recall a cartoon from back in the day where the crab nebula was a big deal, but don't recall name or plot...

Originally Posted by Shostak

A visitor to the solar system like Oumuamua could be interesting. A hard SF game might involve dealing with a too-close-for-comfort trajectory, or sending a team to taking samples or investigate inexplicable radio signals coming from it. A cosmic horror game might make it something whose presence "makes the stars right" for some awful event to become possible. A dungeon fantasy game might give it a treatment similar to Deep Night and the Star.

Clarke's Rama series is the obvious go-to for this, as pretty much the entire Sci-fi community pointed out at once when the thing appeared.

Also, we have the incipient megastructures that may have been detected:

http://arcana.wikidot.com/alien-mega...baffle-scienti

http://arcana.wikidot.com/astronomer...s-dimming-star