The p-process in Type II supernovae.
Abstract
This work presents the first quantitative calculation of p-process yields from the SNII explosion of Z=Zsun_ stars with masses in a large (13<=M/Msun_<=25) range. Use is made of detailed pre-supernova and explosion models. Special attention is also paid to the evaluation of the abundances of the s-process seeds, while the p-process nucleosynthesis is computed with the aid of an extended reaction network. In addition, the impact of some key nuclear physics and astrophysics uncertainties on the p-process yields is also investigated. This unprecedented effort to model the p-process allows us to set the stage of a reliable model for the evolution of the galactic content of the p-nuclides. In particular, integrated p-process yields are obtained from a convolution of the production from the individual star explosions with an Initial Mass Function. In addition, a first quantitative evaluation of the metallicity dependence of the amount of ejected p-nuclides is provided. It is found that the p-process abundance patterns do not depend drastically on the stellar mass. In all the considered cases, about 60% of the p-nuclides are nicely co-produced (with respect to solar). The relative underproduction of the Mo and Ru p-isotopes found in previous studies is confirmed. Another problem is identified, and its extent is evaluated quantitatively for the first time. It concerns the relative global underproduction of the p-nuclides with respect to oxygen by a factor of about 4, when normalized to the solar system values. However, it is claimed that various uncertainties of an astrophysical or nuclear physics nature that can affect both the p-process and oxygen yields do not allow one to rule out the SNII model without further scrutiny. Our predictions are also confronted with anomalies attributed to p-isotopes found in various meteoritic materials. It is found in particular that our calculated Xe isotopic composition fails to reproduce the special pattern of Xe-L loading interstellar diamonds. On the other hand, the radionuclides ^92^Nb & ^146^Sm that are inferred to have been present in the early solar system are synthesized in the SNII p-process at a level that is considered to be too uncertain to allow the development of a reliable p-process chronometry.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 1995
- Bibcode:
- 1995A&A...298..517R
- Keywords:
-
- NUCLEAR REACTIONS;
- NUCLEOSYNTHESIS;
- ABUNDANCES;
- STARS: SUPERNOVAE;
- SOLAR SYSTEM: GENERAL