About Stars: Intermediate Stages (original) (raw)

Stars that have left the main sequence are seldom stable. They run through several phases in which they can pulsate very quickly or also very slowly. There are some kinds of pulsating variables, the most famous are the regular Delta Cepheids.

When leaving the main sequence white and blue stars on their way to red go through a phase as a subgiant and change in the sequence blue - white - yellow - orange - red.

Probably only very few big stars, that have a bit to less mass to become LBV, have as hypergiants another yellow or white phase again short before their end. These stars like Rho Cas are at the Hertzsprung-Russell diagram placed in the yellow evolutionary void, where they can't be stable.

Example: Deneb

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Photo: Nasa