An Etymological Dictionary of Astronomy and Astrophysics

A fairly long-lived step in the evolution of → low-mass
and → intermediate-mass stars when helium burning shifts from the center to a shell around the core. At this phase the stellar luminosity is provided almost entirely by → helium shell burning. The He-shell burning generally adds mass to the growing carbon/oxygen core, resulting in → degenerate matter due to its increasing density.

See also: → early; → AGB; → phase.