How does the nuclear fusion process differ in stars of different masses?

The nuclear fusion process differs in stars of different masses due to varying temperatures and pressures.

In stars with low mass, such as our Sun, nuclear fusion occurs primarily in the core through the proton-proton chain. This process involves the fusion of hydrogen nuclei to form helium, releasing energy in the form of gamma rays and neutrinos. The temperature and pressure in the core are not high enough to initiate fusion of heavier elements.

In contrast, in high-mass stars, fusion occurs through the CNO cycle, which involves the fusion of carbon, nitrogen, and oxygen nuclei. This process requires higher temperatures and pressures than the proton-proton chain. High-mass stars also have a convective core, which allows for mixing of elements and increases the efficiency of fusion.

As high-mass stars age, they undergo a series of fusion reactions that eventually lead to the production of iron. Iron fusion does not release energy, so the star's core collapses under its own gravity, leading to a supernova explosion.

Overall, the nuclear fusion process in stars is dependent on their mass, with higher-mass stars having higher temperatures and pressures in their cores, allowing for fusion of heavier elements. The ultimate fate of a star is also determined by its mass and the fusion reactions that occur throughout its lifetime.