When the [?] decreases it will start to contract. As it contracts it will start to burn [?] for a few hundred million years. When the helium runs out, the sun will [?] and it will burn and explode giving out lots of [?], we call this a [?]. What remains of the sun is a very [?] dense core called a white [?]. Finally it will continue to [?] and getting smaller and dimmer very slowly.