Isotopic r-process abundances and nuclear structure far from stability - Implications for the r-process mechanism

Abstract

The study employs the full isotopic r-process abundances in nature and a unified model for all nuclear properties involved to uniquely deduce the conditions necessary to produce such an abundance pattern. The nature of the steady-flow equilibrium of beta decays between isotopic chains is also investigated. Strong evidence is found to the effect that a steady flow was not global but only local in between neighboring peaks, which requires time scales not much longer than 1 s. The remaining odd-even effects in observed abundances indicate that neutron densities dropped during freeze-out by orders of magnitude on time scales close to 0.04 s. A set of n(n)-T conditions is presented as a test for any astrophysical r-process site. The way remaining deficiencies in the produced abundance pattern can be used to extract nuclear properties far from stability is also shown.