Reviews and Other Views

A review is presented of the p-process in Type II supernovae, one of its goals being to enlighten the changes in views on this nucleosynthesis mechanism since the work of Jean and Jim on the subject in 1975. Specific discussions are also devoted to cases of particular interest, like the light Mo and Ru stable isotopes, the rare nuclide 138 La or the radionuclide 146 Sm. Some comments of diverse natures are also made on the r-process. These considerations do not aim at really providing an exhaustive review of the many nuclear physics and astrophysics intricacies of this process. In contrast, they are hoped to complement or to put in perspective other views that are often expressed in relation with this nucleosynthesis mechanism 1 AN INTRODUCTION TO THE P-PROCESS IN TYPE II SUPERNOVAE The p-nuclides are those neutron-deficient stable isotopes of the elements heavier than iron that cannot be produced by the s-or r-processes of neutron captures. In view of the fact that the number of research papers devoted to the p-process called for their production remains inferior to the number of p-nuclides after more than about 50 years of nuclear astrophysics research, we like to refer to the 'nuclear astrophysics p-nuts' when talking about the p-nuclides. a Either independently or in collaboration, Jean and Jim have had the good taste to contribute to the increase in the number of papers devoted to the p-process. In ref. 1 , Jean put forth the possible spallogenic origin of selected p-nuclides, while in ref. 2 , Jean and Jim pushed to its limits the original proposal 3 to produce the p-nuclides at temperatures in excess of 10 9 K in the H-rich envelopes of Type II supernovae (SNII). Already at the end of the sixties, it was realized that such high temperatures were unlikely to be reached in the envelopes of massive star explosions. This is why one of the authors of this review (M.A.) proposed in his 1971 thesis work (see also ref. 4) to locate the p-process in the deep ONe rich layers of massive stars either in their pre-supernova or supernova phases. a The fact that the p-nuclides are much less abundant (by factors of the order of 100 to 1000) than the corresponding more neutron-rich isotopes in the solar system, which is the only astrophysical location to-date where they are observed, is certainly not a viable explanation for …