What Happens to Stars Much Heavier Than The Sun?
STAGE 3: Supernova Stage
In the final moments of the star's life, nuclear fusion produces an iron core. No energy can be gained by fusing iron into heavier elements. There is now no energy source to sustain the intense internal pressures holding off gravitational collapse. The core collapses catastrophically inward at 1/4 of the speed of light.
In less than 1/10 of a second the core of the star is crushed into a sphere only 100 km across. The gravitational energy released in this fraction of a second is 100 times greater than the sun releases in its entire 10 billion-year lifetime.