As usual, science fiction offers a solution:
The Death Star had some kind of widget in its core/construction/snack machines/whatever that caused that superheated ring when it blew up. Ditto Praxis, which had an atmosphere made of oh, say Klingon farts, which have the same effect.
There doesn't need to be a factual solution for either in either film, especially since both are fantasy. I mean, come ON.
Plus, it's essentially the same special effect, created by computers, which were created by science. So there's your scientific explanation.