![]() We study the evolution of the ratio in the Galactic halo by means of a stochastic chemical evolution model considering merging neutron stars as polluters of europium. Future high-resolution spectroscopic surveys, such as 4MOST and WEAVE, will produce the necessary statistics to constrain at best this parameter. Adopting our best model, we also reproduce the dispersion of at a given metallicity, which depends on the fraction of massive stars that produce neutron star mergers. We confirm that the mixed scenario with both merging neutron stars and supernovae as europium producers can provide a good agreement with the data relaxing the constraints on the distribution time delays for the coalescence of neutron stars. Our best model is obtained by relaxing point iv) and assuming a fraction that varies with metallicity. The stochastic chemical evolution model can reproduce the trend and the observed spread in the data with neutron star mergers as unique producers if we assume: i) a delay time distribution $\propto t^$ and iv) a constant fraction of massive stars in the initial mass function (0.02) that produce neutron star mergers. We improved our previous stochastic chemical evolution model by adding a time delay distribution for the coalescence of the neutron stars, instead of constant delays. Our result indicates that the ν/p-process in CCSNe (other than ECSNe) can be the origin of p-nuclei up to A = 108, and even up to A = 152 in limiting conditions. We also explore the sensitivities of some key nuclear reaction rates to the nucleosynthetic abundances. ![]() We further study the νp-process with semi-analytic models of neutrino winds assuming the physical conditions for CCSNe. Our models do not confirm ECSNe as sources of the strong r-process (but possibly of a weak r-process up to Pd, Ag, and Cd in the neutron-rich lumps) nor of the νp-process in the subsequent proton-rich outflows. Our nucleosynthesis calculations indicate that these neutron-rich lumps allow for interesting production of elements between iron group and N = 50 nuclei (Zn, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, with little Ga). New 2D explosion simulations of electron-capture supernovae (ECSNe a subset of CCSNe) exhibit, however, convective neutron-rich lumps, which are absent in the 1D case. This seems to exclude all possibilities of neutron-capture nucleosynthesis, but provide ideal conditions for the νp-process, in neutrino winds. Recent one-dimensional (1D) hydrodynamical simulations of core-collapse supernovae (CCSNe) with a sophisticated treatment of neutrino transport indicate the neutrino-driven winds being proton-rich all the way until the end of their activity.
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