What leads to a star transitioning into a Red Giant phase after core hydrogen depletion?
Answer
Shell burning of hydrogen generates more energy than prior core burning.
As the helium core contracts, the material just outside it heats up enough to ignite hydrogen fusion in a shell. This shell burning is more exothermic than the previous core burning, causing the star's outer envelope to swell dramatically.
Frequently Asked Questions
What event immediately triggers the contraction of the inert helium core in a star?What leads to a star transitioning into a Red Giant phase after core hydrogen depletion?Approximately what core temperature must be reached for helium fusion to commence?What unstable isotope is formed as the initial step in the Triple-Alpha Process?What fundamental physical concept supports the core of a Sun-like star when it first reaches helium ignition temperatures?Why does helium ignition cause an explosive Helium Flash in low-mass stars?How do stars significantly more massive than the Sun ($ ext{e.g., } > 2 M_{ ext{Sun}}$) regulate helium ignition?What process is responsible for synthesizing the first stable carbon atoms in the universe within stars?Compared to hydrogen fusion, how much energy per kilogram does helium fusion typically release?What approximate core temperature must be reached to initiate the fusion of Carbon-12 with helium to form Oxygen-16?