Answer:
Brainliest?
Explanation:
Once the hydrogen fuel in the core of a low mass star is used up, this marks the Main-Sequence Turnoff Point. Hydrogen fusion is still occurring, but in a shell that surrounds the core. All that is left in the core is helium ash. In a nutshell, this is what happens next:
Hydrogen shell continues fusion
Helium ash from hydrogen shell collects at the core - the core has remnant helium ash from prior core fusion
Helium ash build as does pressure and temperature - helium flash then core helium fusion
hydrogen shell and helium core fusion continues - core helium fusion ends soon (more heat, faster burning)
Ash in core now carbon, helium shell burning begins, hydrogen shell burning continues
Carbon ash compresses as outer layers fluctuate
Outer layers shed in planetary nebula
Inert, compressed carbon core (White Dwarf) remains
