Massive stars on the upper end of the main sequence generate energy by means of the

Question

Quizplus · Accepted Answer

Massive stars on the upper end of the main sequence generate energy by means of the CNO cycle, where carbon, nitrogen and oxygen act as catalysts for converting hydrogen into helium. This is different from smaller stars, which primarily use the proton-proton cycle to generate energy. The triple alpha reaction is primarily important in the later stages of massive star evolution, when helium nuclei fuse to form heavier elements in the core. Radiation pressure is a result of the energy produced by nuclear fusion reacting against the gravitational pressure of the star.

Massive Stars on the Upper End of the Main Sequence