Can a star become a red giant more than once?

Question

Quizplus · Accepted Answer

Stars can indeed become red giants more than once. Initially, they expand into red giants as they exhaust their hydrogen fuel and begin burning helium in their cores. After the helium flash, a period where helium burning starts explosively but then settles down, they can contract and later expand again into a red giant phase as they start burning heavier elements in shells around the core. This process does not involve crossing the Chandrasekhar Limit or result in a Type II supernova for the star's mass range where red giant phases occur, nor does it involve the complete loss of outer shells as in the formation of a planetary nebula at this stage.

Can a Star Become a Red Giant More Than Once