Supernova

So heavier elements continue to fuse at the core. The reactions continue until the heavier elements begin fusing Iron. The fusion of Iron **takes** energy rather than releasing it. In other words Iron fusion absorbs heat from the core. The rapid drop in temperature at the core means that the outward pressure ends. The inwards force of gravity crushes the core. At this stage the star's core is about a billion times more dense than the Earth (and about the same size!)

When the star's core is withered to the size of the Earth the critical instant arrives when the nearly exhausted nuclear furnace no longer radiates enough energy to overcome the fierce inward pull of its own gravity.

In less than a second the outer core layers collapse and literally bounce off the superdense core. The ultra-dense nuclear material rebounds, sending a shock wave smashing outward through the inrushing outer layers of star material. Bang. The explosion releases as much energy as the sun radiates in 10 billion years, with a flare of light momentarily as bright as an entire galaxy!

What happens next?
 * This fate is reserved for stars ten times more massive than our Sun**.