What is the end stage of a medium mass star after it has expanded into a giant red star?

The end stage of a medium mass star, after it has gone through the red giant phase, is a white dwarf. This occurs as the star exhausts its nuclear fuel and undergoes significant changes. During its lifetime, a medium mass star (like our Sun) fuses hydrogen into helium in its core. Once hydrogen is depleted, the core contracts under gravity, causing temperatures to rise and the outer layers to expand into a red giant.

As the star continues to evolve, it eventually sheds its outer layers, creating a planetary nebula. What remains is the hot core, which is the white dwarf. A white dwarf is primarily composed of carbon and oxygen and, without further nuclear fusion occurring, it will gradually cool and dim over time.

This process differs from the fates of other stellar objects. For example, high-mass stars can end as neutron stars or black holes after going through supernova events. The red supergiant phase is typically linked to these more massive stars rather than medium mass stars. Therefore, the transition of a medium mass star to a white dwarf after the red giant phase is a key concept in stellar evolution.