Hi All,
Our own Solar System is believed to have been a super nova in the beginning. A dying star, exploding. The gases recombining to form the sun and planets. 4.65 billion years ago.
The nebula if large enough may combine or dissperse. It depends on what the trigger is. I assume there being no trigger, nothing happens.
That is what I understand from some of the DVD documentaries I have watched on the subject.
Cheers Marty