Stars evolve primarily because they use up the fuel in their cores.

Question

Quizplus · Accepted Answer

As stars fuse hydrogen into helium in their cores, they release energy in the form of light and heat. This energy creates the outward pressure that counteracts the force of gravity, keeping the star stable. However, once the hydrogen fuel is depleted, the core begins to contract and heat up, which eventually causes heavier elements to fuse in a process called nucleosynthesis. This produces more energy and causes the outer layers of the star to expand and cool, turning it into a red giant or supergiant. Depending on the size of the star, it may go through further stages of nuclear fusion and collapse before ending its life as a white dwarf, neutron star, or black hole.

Stars Evolve Primarily Because They Use Up the Fuel in Their