Fusing Iron Together Cools Stars

When you put heavier and heavier nuclei together, they are not as tightly bound. They're easier to break up. And so if you transition from a nucleus which is more tightly bound to less tightly bound, then it costs energy to do that. So in effect, you're like putting out the fire of the star. Instead of fueling it for the next reaction, you're cooling it down. That's why we can't make things heavier than iron because it cools stars. But imagine some more massive star that's hotter at its core and is capable of fusing all the way up to iron. It tends to kill the star right away. You know, why can't the sun