I made a scenario out of a similar event.
I was playing like a neutral race, sticking to one system, and only letting a handful of scouts out for quick peeks to chart the nearest systems.
I was up to near-max tech with a really nice, fully colonized and optimized system.
Then one of my stars (binary system) went unstable.
I saved it, and added some scenario-type "meeting with your ministers" screens along with a countdown.
You've got a mere 30 turns to build transports, shove your people in and then attack through the warppoints to push an AI out of its established territory before your system goes boom and you have to mothball all your dreads.
Then you have to eke out an existence with puny little colonies under hostile atmospheres while huge AI empires run around the galaxy.
If you have SE4 classic (v1.49), you can download it from
http://imagemodserver.mine.nu/other/MM/SE4
Get the scenario (under scenarios), plus P&N v2.3c (under mods).