Modern r-process calculations from the waiting-point concept to full dynamical network calculations
Khalil Farouqi, University of Chicago
In an attempt to constrain the astrophysical conditions for the nucleosynthesis of the classical r-process elements beyond Fe, we have performed large scale dynamical network calculations within the model of an adiabatically-expanding, high-entropy wind (HEW) of type II supernovae (SN II). A superposition of several entropy components (S) with model inherent weightings results in an excellent reproduction of the overall Solar system (SS) isotopic r-process residuals (Nr,⊙), as well as the more recent observations of elemental abundances of metal-poor, r-process rich halo-stars in the early Galaxy. For the heavy r-process elements beyond Sn, our HEW model predicts a robust abundance pattern up to the Th, U r-chronometer region. For the lighter neutron capture region, an S dependent superposition of (i) a normal component directly producing stable nuclei, including s-only isotopes, and (ii) a component from a neutron rich freezeout followed by the rapid recapture of beta delayed neutrons emitted from the far unstable seed nuclei is indicated.