Evolution off the Main Sequence: Expansion into a Red Giant
Hydrogen in the core completely converted
into He:
H burning continues in
a shell around the core.
He core + H-burning
shell produce more energy than needed for pressure
support
Expansion and cooling
of the
outer layers of the star ® red giant
® “Hydrogen
burning” (i.e. fusion of H into He) ceases in the core.
