Mixing and nucleosynthesis in rotating TP-AGB stars

We present the first evolutionary models of interme- diate mass stars up to their thermal pulses which include effects of rotation on the stellar structure as well as rotationally in- duced mixing of chemical species and angular momentum. We find a significant angular momentum transport from the core to the hydrogen-rich envelope and obtain a white dwarf rota- tion rate comparable to current observational upper limits of . 50 kms 1 . Large angular momentum gradients at the bottom of the convective envelope and the tip of the pulse driven convective shell are shown to produce marked chemical mixing between the proton-rich and the 12 C-rich layers during the so called third dredge-up. This leads to a subsequent production of 13 C which is followed by neutron production through 13 C(; n) in radiative layers in between thermal pulses. Although uncertainties in the efficiency of rotational mixing processes persist, we conclude that rotation is capable of producing a 13 C-rich layer as required for the occurrence of the s-process in TP-AGB stars.