How much time/lifespan does the sun of Athas have left, scientifically speaking?

I realize that magic ignores physics, and that rpg games are notoriously inaccurate… but I’m curious if a close enough or approximate answer can be deduced.

Given that, do the changes to the sun of Athas match up with any scientifically known stellar life cycle, if so, roughly how much lifespan can be estimated for the sun of Athas have left, barring further meddling or tampering with the star?

I am looking for a rough estimate if possible, well reasoned speculation, if not. 2e, 3e, & 4e are valid sources. I’m not looking for a setting specific answer, but a general answer.