Astronomy › Section P · Stars from adolescence to old age › Topic P.1
From the main sequence to red giants
Stars spend most of their lives quietly fusing hydrogen on the main sequence, but that calm cannot last. When the hydrogen in the core runs out, the core shrinks, the outer layers balloon, and the star becomes a red giant.
In this topic
- The long middle of a star's life
- Changing on the main sequence
- Worked example: a sensitive furnace
- Lifetime depends on fuel and spending
- Worked example: how long do they last?
- When the core runs dry
- The star swells
- Worked example: how big is a red giant?
- On the H-R diagram, and a famous supergiant
- Common mistakes to avoid
- Key takeaways
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