An Etymological Dictionary of Astronomy and Astrophysics

A → dredge-up process that occurs in the stellar interior during He shell burning, as in → asymptotic giant branch (AGB) stars.
These stars consist of a degenerate carbon-oxygen core, surrounded by a helium-rich region, above which lies a hydrogen-rich convective envelope. Following thermal pulses of the helium-burning shell, the convective envelope moves inward in mass, penetrating the hydrogen-exhausted regions. This is known as third dredge-up. As convection moves inward, nuclear processed materials are carried to the surface.

See also: → third; → dredge-up.