Evolution Off Main Sequence
When the Sun runs out of Hydrogen in the core, the balance between
gravity and pressure is lost. Gravity forces the star to shrink until
a shell of hydrogen around the core of Helium begins to burn.
- Why doesn't the core of helium start fusing?
- What happens to the size of the helium core during shell burning?
- What happens to the temperature of the helium core?
- What is happening to the size of the Sun?
- Compare Hydrogen shell burning as a red giant to Hydrogen
core burning as a main sequence star.