What is the relationship between a star's mass and its brightness on the main sequence?

Answer

More massive stars must generate higher core temperatures, resulting in a higher rate of fusion and greater brightness.

A more massive star has greater gravity to counteract; thus, it must generate higher core temperatures and a higher rate of fusion, leading to significantly greater outward pressure and brightness.

What is the relationship between a star's mass and its brightness on the main sequence?
stabilitygravitystarastrophysicspressure