Here's why:
* Mass dictates initial temperature and pressure: A star's mass directly influences the temperature and pressure at its core during formation. More massive stars have higher core temperatures and pressures.
* Nuclear fusion rate: Higher temperatures and pressures lead to a faster rate of nuclear fusion, the process that fuels stars. This means massive stars burn through their fuel much faster.
* Lifespan and death: Because of the faster burn rate, massive stars have shorter lifespans. They also experience a more dramatic end, often exploding as supernovas. Smaller stars, like our Sun, live longer and have less dramatic deaths, becoming white dwarfs.
* Evolutionary stages: The mass of a star determines the various stages it will go through during its lifetime. For example, massive stars might experience red supergiant phases, while smaller stars might become red giants.
In addition to mass, factors like the star's composition and its surrounding environment also play a role in its life cycle, but mass is the most dominant factor.
