M sun will end as white dwarfs.
White dwarfs are compact objects supported by degeneracy pressure.
M sun will end their lives as white dwarfs. A star radiates energy into space because it is hot. The energy lost into interstellar space is replenished by fusion. When fusion stops, the lost energy is no longer replaced, and the temperature and pressure within the star drop. When the radius and masses of white dwarfs such as Sirius B were first computed, astronomers were flabbergasted.