If a star is not massive enough to fuse carbon or oxygen after helium burning, what does it become?

Answer

A white dwarf

Lower-mass stars that cannot trigger fusion of heavier elements like carbon or oxygen after the helium burning phase will shed their outer layers and end their lives as a comparatively gentle white dwarf.

If a star is not massive enough to fuse carbon or oxygen after helium burning, what does it become?
instabilitystar