Red giant branch
= Red giant branch
{wiki}
The phase of <stellar evolution> in which hydrogen-shell <nuclear fusion> surrounds an inert helium core and the envelope expands and cools. Low-mass <stars> climb toward helium ignition with growing core mass and <luminosity>; their cores become supported by <electron degeneracy pressure>. A <red giant> is a broader observational category and need not be on this particular evolutionary branch.