What critical element stops fusion in massive stars because fusing it consumes energy rather than releasing it?

Answer

Iron

Massive stars continue fusion up to iron in their cores; when the core is made of iron, the outward pressure from fusion ceases abruptly because fusing iron consumes energy, leading to catastrophic gravitational collapse.

What critical element stops fusion in massive stars because fusing it consumes energy rather than releasing it?

#Videos

What Factors Determine A Star's Final Lifecycle? - Physics Frontier

deathastronomystarstellar evolutionmass