Evolution of massive AGB stars. III.

We analyse their structural and evolutionary properties and determine the first SAGB yields. Stellar models of various initial masses and metallicities were computed using standard physical assumptions which prevents the third dredge-up.

A postprocessing nucleosynthesis code was used to compute the SAGB yields, to quantify the effect of the third dredge-up (3DUP) and to assess the uncertainties associated with the treatment of convection. Owing to their massive oxygen-neon core, SAGB stars suffer weak thermal pulses, have very short interpulse periods and develop very high temperatures at the base of their convective envelope (up to 140x10^8^K), leading to very efficient hot bottom burning.