What is the fate of a Sun-sized star after it exhausts its nuclear fuel?

When a Sun-sized star exhausts its nuclear fuel, it undergoes a series of transformations that ultimately lead to its evolution into a white dwarf. This process begins when the star has depleted its hydrogen fuel in the core, leading to a lack of nuclear fusion. As fusion ceases, gravitational forces start to dominate, causing the core to collapse under its own weight while the outer layers expand. This expansion can create what is known as a red giant phase, but eventually, the outer layers are shed, and the core that remains is very hot and dense.

The core, now primarily composed of carbon and oxygen, settles into a stage where it no longer undergoes significant nuclear reactions. It radiates energy as it cools down, becoming a white dwarf. A white dwarf is essentially the remnant core of the star, with a mass comparable to that of the Sun but packed into a volume similar to that of Earth. White dwarfs can shine brightly for billions of years as they gradually cool down.

In contrast, neutron stars and black holes are typically the remnants of more massive stars, which have different evolutionary paths after exhausting their nuclear fuel. A red supergiant represents a stage in a much more massive star's life, leading to a supernova