What causes a star significantly more massive than the Sun to undergo core collapse?

Answer

The build-up of iron in the core removes the energy source sustaining outward pressure.

For stars significantly larger than the Sun, the fusion chain terminates when the core becomes iron. Because fusing iron requires energy input rather than providing energy output, the outward pressure support fails instantly, leading to gravitational implosion.

What causes a star significantly more massive than the Sun to undergo core collapse?
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