Why does the duration over which a massive star fuses elements decrease from hydrogen to iron?
A) The core temperature increases.
B) The star produces less energy per fusion reaction.
C) The core density increases.
D) all of the above

Question

Quizplus · Accepted Answer

As a massive star fuses elements from hydrogen to iron, the core temperature increases due to the gravitational pressure, but the efficiency of fusion reactions decreases. Additionally, the core density also increases as heavier elements are produced, which further enhances the fusion rate. Therefore, all of the choices apply to the decrease in the fusion duration over the star's lifetime.

Why Does the Duration Over Which a Massive Star Fuses