出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The s-process production in massive stars at very low metallicities is expected to be negligible
due to the low abundance of the neutron source 22Ne, to primary neutron poisons and decreasing
iron seed abundances. However, recent models of massive stars including the effects of rotation
show that a strong production of 22Ne is possible in the helium core, as a consequence of the
primary nitrogen production (observed in halo metal poor stars). Using the PPN post-processing
code (developed within the NuGrid collaboration), we study the impact of this primary 22Ne on
the s process. We find a large production of s elements between strontium and barium, starting
with the amount of primary 22Ne predicted by stellar models including the effects of rotation.
There are several key reaction rate uncertainties influencing the s-process efficiency. For example,
within the nuclear reaction rate uncertainty, the 17O(a, g) reaction may either be critically important
or negligible. We also report on the development of the new parallel (MPI) post-processing
(MPPNP) variant of the PPN code designed to follow the complete nucleosynthesis in stars on
highly resolved grids. We present here the first post-processing run from the ZAMS up to the end
of helium burning for a 15 M model.
