Principle of universality of -process nucleosynthesis in core-collapse supernova explosions

Hayakawa, Takehito; Iwamoto, Nobuyuki  ; Kajino, Toshitaka*; Shizuma, Toshiyuki; Umeda, Hideyuki*; Nomoto, Kenichi*

Using core-collapse supernova explosion models, we investigate the principle of the universality of the -process that the s/p abundance ratios produced by individual nucleosynthesis are almost constant in the wide region of the atomic number. The universality originates from the weak -process in pre-supernovae, the independence of the s/p abundance ratios of the nuclear reactions, and the shift of the -process layers. Our calculations further suggest an extended universalitythat the s/p ratios in the -process layers are not only constant but also centered around a specific value 3. To verify this, we propose an astronomical observation of Indium isotopic abundance fractions.