No it's not a star. It's what they want you to think. But really it's a planet with aliens inside but the heat and all that hot jazz is there protection so they are safe inside but so hot outside that no one would attack them ^.^
actually, yes, the sun is, in fact, a planet. it's inhabited by genius isolationists that created a large, flaming force field around the planet so no one could get to them. scientists just made up the whole thing about it being a star.