What happens if the core is hot enough for fusion?
- New reactions ignite
- core size stable
- shell fusion continues
- outer layers readjust
What happens when the fuel runs out of the core?
- Core collapses
- outer layers escape
Is the core hot enough for fusion?
- For less than 1/4 solar mass star, never
- In larger stars, "triple-alpha" process
What happens in the Asymptotic-Giant Branch? Is this the end of the line?
- The helium fusion dies out; dead carbon core
- cycle repeats
- At this point, solar mass star collapses to a white dwarf
- Outer layers expand as a "planetary nebula"