Asymptotic Giant Branch

A period of stellar evolution undertaken by all low to intermediate mass stars (0.6-10 solar masses) late in their life. The Asymptotic Giant Branch is the name given to a region of the Hertzsprung-Russell Diagram populated by evolving low to medium-mass stars. When a star exhausts the supply of hydrogen in its core, the core contracts and its temperature increases, causing the outer layers of the star to expand and cool. The star's luminosity increases greatly, and it becomes a red giant, following a track leading into the upper-right hand corner of the HR diagram.
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