Why do massive stars have shorter lifespans than less massive stars?

Massive stars have shorter lifespans than less massive stars primarily because they burn through fuel faster. This phenomenon is due to the fact that massive stars possess greater gravitational pressure at their cores, which leads to more intense and rapid nuclear fusion processes.

In these stars, the rate of fusion increases significantly compared to their less massive counterparts, resulting in a much more rapid consumption of hydrogen and other nuclear fuel. For instance, while a small star might maintain a stable fusion rate for billions of years, a massive star may exhaust its hydrogen supply in just a few million years. As a result, their lifespans are considerably shorter, despite having more fuel available initially.

The notion of slower fusion is not applicable because massive stars actually undergo fusion at a much faster rate. Their larger size contributes to their increased gravitational pressure but does not directly correlate to having a longer lifespan. Moreover, the energy emitted by massive stars is indeed greater due to their more vigorous fusion reactions, contrasting with the idea of emitting less energy.