Impact Of Rotation And Convective Boundary Mixing In Low Mass Agb Stars

After central He burning exhaustion, stars with an initial mass of 1.5-3 solar masses start the AGB phase. In this phase, the s-process takes place, which is producing about half of all elements heavier than iron. We calculated non-rotating AGB stellar models with MESA and included a treatment of convective boundary mixing (CBM) based on the results of hydrodynamic simulations and on the theory of mixing due to gravity waves in the vicinity of convective boundaries. We show examples of how the models compare with spectroscopic abundance observations. In particular, our models reproduce the highest observed values of the s-process index [hs/ls]. On the other hand, the full range of the observed [hs/ls] as well as the laboratory measurement of Zr isotopic-ratios were not completely reproduced. A spread of initial rotational velocity in AGB stars might help to improve this. We are calculating stellar evolution models including both rotation and the above described ingredients, enabling us to analyse their interplay and the impact on s-process efficiencies.