Barium star population synthesis with an improved TP-AGB model

We explore the formation of barium stars by carrying out stellar population synthesis, using a rapid synthetic binary star evolution code which includes nucleosynthesis and an up-to-date treatment of AGB evolution. Similarly to other studies, we find that the orbital period distribution and eccentricities predicted for the systems are in disagreement with observations. In search of a solution for this, we discuss some ingredients that may be missing in the current binary interaction models, especially the possibility of mass accretion during the common envelope phase and additional energy sources that may help to expel the common envelope.