What outcome occurs when gravity wins the initial skirmish after the core hydrogen fuel is exhausted?

Answer

The core contracts and heats intensely, often igniting fusion in a shell around the core, leading to a red giant.

When gravity wins post-main sequence, the core contracts and heats intensely. This heat can then ignite fusion in a surrounding shell, causing the outer layers to expand enormously into a red giant.

What outcome occurs when gravity wins the initial skirmish after the core hydrogen fuel is exhausted?
stabilitygravitystarastrophysicspressure