How does the primary energy generation mechanism affect luminosity rules when a star evolves off the main sequence?

Answer

Luminosity becomes a product of shell burning and core contraction

While main-sequence stars follow rules where higher mass means higher luminosity, once evolved off the main sequence, luminosity is dictated by the new internal processes like core contraction and shell burning.

How does the primary energy generation mechanism affect luminosity rules when a star evolves off the main sequence?
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