Razore.. the sun can't get bigger if it has a nova or supernova
A nova is when a star explodes.. a supernova is when a really large star explodes.
If our sun were to blow up at it's current size, it would be a nova.. THough it would pritty much destroy every planet up to jupiter.
Now the way theory has it. THe sun will expand into a red giant, destroying every planet up to the asteroid belt because it will be that big. THen it will shrink down again to a size up from what it is now. THen it will go up again to a super giant.. Then it will explode in a supernova.
After this.. 2 things could happen. If the core still survives the blast, it will just be a dead star..
If the core gets crushed with it's own gravity, then a black hole formes. Either way this whole solar system is forked.
Now this galaxy will live on prabably forever. Unless somehow a large enough black hole forms that sucks all matter into it.
Which if it were that big, it would prabably do the same to galaxies near us.