Eur. Phys. J. A (2006) 27: 123-128
https://doi.org/10.1140/epja/i2006-08-017-6

Nuclear Physics in Astrophysics II

Evidence for p-process nucleosynthesis recorded at the Solar System abundances

¹ Advanced Photon Research Center, Japan Atomic Energy Research Institute, 619-0215, Kizu, Kyoto, Japan
² Department of Nuclear Energy System, Japan Atomic Energy Research Institute, 319-1195, Tokai, Ibaraki, Japan
³ National Astronomical Observatory, Osawa, 181-8588, Mitaka, Tokyo, Japan
⁴ Department of Astronomy, School of Science, University of Tokyo, 113-0033, Tokyo, Japan

^* e-mail: hayakawa.takehito@jaea.go.jp

Received: 17 June 2005
Accepted: 20 December 2005
Published online: 13 March 2006

Abstract

Analyzing the Solar System abundance, we have found two universal scaling laws concerning the p- and s-nuclei with the same atomic number. They are evidence of the p-nucleus origin that has been discussed for long years. The first scaling is the correlation of the isotope abundances between a p-nucleus and an s-nucleus that is two neutron heavier than the p-nucleus. The abundance ratios of the s-nucleus to the p-nucleus are almost constant in a wide range of atomic numbers. This scaling indicates that the p-nucleus is dominantly produced from the s-nucleus by (γ, n) reactions in huge photon bath in supernova explosions. The second scaling indicates that the isotope abundance ratio between two p-nuclei with the same atomic number is almost unity. These two scalings are a new useful method to verify nucleosynthesis models for the p-process. We have calculated these ratios by a p-process nucleosynthesis based on a typical core-collapse supernova explosion model. The results are consistent with the scaling in the solar abundances. In addition, the scalings provide new concepts: a universality of the p-process, a rate meter for the s-process and a new nuclear cosmochronometer.