Abstract
A number of naturally occurring, proton-rich nuclides (the p-nuclei) cannot be made in the s- and r-process. It has been found that massive stars can produce p-nuclei through photodisintegration of pre-existing intermediate and heavy nuclei. This so-called gamma-process requires sufficiently high temperatures and occurs in pre-explosive or explosive O/Ne burning, depending on the mass of
the star. Although the gamma-process has been successful in producing a large range of p-nuclei, two mass regions remain problematic, A < 110 and 150 < A < 165, where a number of p-nuclei are severely underproduced. The origin of the problems is yet to be identified. A large number of unstable nuclei with only theoretically predicted reaction rates are included in the reaction network and thus the nuclear input may involve uncertainties. Deficiencies in charged-particle
optical potentials at gamma-process temperatures have been found for nuclei at stability. On the other hand, the gamma-process conditions (temperature profiles, entropy of the O shell, seed composition) also sensitively depend on details of the stellar structure and evolution, as well as on the initial
metallicity. Nevertheless, especially the deficient low-mass p-nuclei may call for an additional production process or site, such as production in (subChandrasekhar) type Ia supernovae. Also the (im)possibility of a synthesis in the rp- and nu-p-processes is discussed. Were this the case, the production of p-nuclei would be realized as a superposition of several different processes, not
necessarily in the same site.
the star. Although the gamma-process has been successful in producing a large range of p-nuclei, two mass regions remain problematic, A < 110 and 150 < A < 165, where a number of p-nuclei are severely underproduced. The origin of the problems is yet to be identified. A large number of unstable nuclei with only theoretically predicted reaction rates are included in the reaction network and thus the nuclear input may involve uncertainties. Deficiencies in charged-particle
optical potentials at gamma-process temperatures have been found for nuclei at stability. On the other hand, the gamma-process conditions (temperature profiles, entropy of the O shell, seed composition) also sensitively depend on details of the stellar structure and evolution, as well as on the initial
metallicity. Nevertheless, especially the deficient low-mass p-nuclei may call for an additional production process or site, such as production in (subChandrasekhar) type Ia supernovae. Also the (im)possibility of a synthesis in the rp- and nu-p-processes is discussed. Were this the case, the production of p-nuclei would be realized as a superposition of several different processes, not
necessarily in the same site.
| Original language | English |
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| Title of host publication | Procs 11th Symposium on Nuclei in the Cosmos (NIC XI) |
| Publisher | SISSA |
| Number of pages | 10 |
| Publication status | Published - Jan 2011 |
| Event | 11th Symposium on Nuclei in the Cosmos - Heidelberg, Germany Duration: 19 Jul 2010 → 23 Jul 2010 |
Publication series
| Name | Proceedings of Science |
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| ISSN (Electronic) | 1824-8039 |
Conference
| Conference | 11th Symposium on Nuclei in the Cosmos |
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| Country/Territory | Germany |
| City | Heidelberg |
| Period | 19/07/10 → 23/07/10 |