The s process in massive stars

In the past decades considerable progress has been made in the understanding of the various processes responsible for the nucleosynthesis of the elements in stars. This holds especially for the main s process in low-mass AGB stars, which is largely responsible for the production of about half of the elemental abundances in the mass range 90≤A≤20990≤A≤209. The weak s process, which produces elements with A≤90A≤90, however, is much less understood. A better characterization of the weak s component would help to disentangle the various processes contributing to element production in this region. In this respect, more accurate neutron capture cross sections in the mass range 56≤A≤9056≤A≤90 are indispensable. Also, neutron captures on abundant light elements with A<56A<56 play an important role, since they act as neutron poisons and affect the stellar neutron balance. In this context, the impact of new results for neutron capture cross sections on light and medium mass nuclei is discussed.