Annu. Rev. Astron. Astrophys. 1994. 32: 153-90
Copyright © 1994 by . All rights reserved

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The terms r-, s-, and p-processes have been successful in clarifying our picture of heavy-element formation. In this paper, we have seen that this is because these different processes reflect the responses a nucleosynthetic system can have to being out of equilibrium. In this way, our understanding of the mechanisms of heavy-element synthesis is firm.

Future work will continue to focus on using all clues at our disposal to resolve the problems surrounding the astrophysical sites for these processes. Important questions we must seek answers to in the near future include: 1. Do nascent neutron star winds have high enough entropies to drive a full r-process?, 2. Do 13C pockets really form in low-mass AGB stars, and do they give the right neutron exposures for the s-process?, and 3. Can type Ia supernovae make the p-nucleus 92Mo? That we can ask such specific questions indicates that we have good ideas about the sites for the r-, s-, and p-processes. That we do not have answers shows that we have much work to do.


The author is grateful to G.M. Fuller, W.M. Howard, G.J. Mathews, and S.E. Woosley for discussions and to N. Luo for assistance. He is especially grateful to M.F. El Eid for discussions and for some of the subroutines necessary to compute the results shown in Figures 3, 4, 5, and 6, and to D.D. Clayton for a critical reading of the manuscript. This work was supported in part by NASA grant NAG W-3480.

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