What element's formation halts continuous fusion in the core of a Red Supergiant because its fusion consumes energy?

Answer

Iron (Fe56)

Fusion continues until the central product becomes iron ($ ext{Fe}^{56}$), as fusing iron nuclei consumes energy instead of releasing it, removing the thermal support against gravity.

What element's formation halts continuous fusion in the core of a Red Supergiant because its fusion consumes energy?

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How Do Red Giants Become Supernovae? - Physics Frontier

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