The core collapse phase at the end of the life of a massive star is triggered when
A) the helium flash and thermal pulses have expelled the star's envelope.
B) nuclear fusion has produced a significant amount of iron in its core.
C) the core becomes as dense as an atomic nucleus.
D) the density reaches a threshold at which electron degeneracy pressure begins to play a role.

Question

Quizplus · Accepted Answer

The core collapse phase in a massive star's life is triggered when nuclear fusion in the core has produced a significant amount of iron. Iron fusion consumes energy rather than releasing it, leading to a loss of pressure support and eventual collapse of the core.

The Core Collapse Phase at the End of the Life