What is the final stage of life for a star as massive as the Sun?

After stars like the Sun expand to become red giants, they will end their lives as a white dwarf star, until finally dimming to become a black dwarf. White dwarf stars are made from the collapsed cores of red giants, once the outer layers of the star have been expelled.

Main-sequence stars, like the Sun, will swell to become red giant stars once they have fused all of their hydrogen into helium. White dwarf stars are made up of the cores of red giants, and will end their lives as black dwarfs once they have radiated all of their energy and dimmed.