The third of these events begins when a star joins the asymptotic giant branch. For 10 points each:
[10h] Name these events in the life of a star in which the lower boundary of the convection zone extends far enough down that nucleosynthesis products can move up through the star.
ANSWER: dredge-ups [or third dredge-up]
[10e] The first dredge-up occurs as a star leaves this class of stars, which forms a diagonal region on the Hertzsprung-Russell diagram that contains the Sun.
ANSWER: main sequence
[10m] The depth reached during dredge-up depends on this quantity, which is the proportion of constituents of a star that are not hydrogen or helium.
ANSWER: metallicity
<Joseph Krol , Science - Astronomy - any>