A brief period of hydrogen-shell burning sees its luminosity rise as with higher-mass stars. Unable to release energy from In stars around the mass of the sun, this begins at the tip of the red giant branch with a helium flash from a degenerate helium core, and the star moves to the horizontal branch where it burns helium in its core.
What happens during the hydrogen shell burning phase?
Once the hydrogen in the core has all been burned to helium, energy generation stops and the core begins to contract. This raises the internal temperature of the star and ignites a shell of hydrogen burning around the inert core.
What is hydrogen shell burning?
Shell burning is the fusion of hydrogen, helium, and other elements in regions of a star's interior outside the stellar core. As the particular fuel is progressively exhausted, the shell moves outward until it comes to regions too cool to sustain the reactions.
