How will an isolated one solar-mass star die?

An isolated one solar-mass star will eventually exhaust its hydrogen fuel in the core, leading to hydrogen shell burning around an inert helium core. As it expands into a red giant, it will undergo helium fusion into carbon and oxygen. Once the helium is depleted, the star lacks sufficient mass to ignite further fusion processes and will shed its outer layers, creating a planetary nebula, while the core collapses into a white dwarf. This white dwarf will gradually cool and fade over billions of years.