The origin of the proton-rich and neutron-rich isotopes
speaker: Yuta Yamazaki
Abstract:
The origin of heavy elements is still unclear. The process and astrophysical site of the nucleosynthesis of neutron-rich and proton-rich nuclei have long been under debate. This study tries to reveal the origin of these nuclei through galactic chemical evolution calculations. Neutron-rich nuclei are synthesized by a fast neutron capture process, r-process. The observational evidence suggests that galactic stars have very similar compositions of the elements synthesized in this process. We have discovered the possibility that there is diversity in the mass A-distribution, while maintaining the universality of the elemental abundance. This also allows us to quantitatively discuss the contributions from multiple candidates of r-process sites. For the source of proton-rich nuclei, the gamma process, which has been studied for a long time, is difficult to produce a sufficient amount of. The vp-process involving neutrinos has recently been widely studied as a candidate of proton-rich production process. In general, it is difficult to find observational evidence of proton-rich nuclei nucleosynthesis because of their low fraction in the elemental abundance. However, we have discovered the possibility of observing a contribution from the vp process to the Molybdenum elemental abundances of metal-poor stars in galaxies.