In a high-mass giant star, which element's formation in the core causes the fusion energy release mechanism to fail catastrophically?

Answer

Iron

In massive stars, fusion proceeds until the core fills up with iron; iron is the heaviest element produced by fusion that releases energy, so its formation causes the core support mechanism to fail instantly.

In a high-mass giant star, which element's formation in the core causes the fusion energy release mechanism to fail catastrophically?
SpaceastronomyCorestargiant