Impact of Hypernova νp-process Nucleosynthesis on the Galactic Chemical Evolution of Mo and Ru

Abstract

We calculate the Galactic Chemical Evolution of Mo and Ru by taking into account the contribution from ν p-process nucleosynthesis. We estimate yields of p-nuclei such as 92,94Mo and 96,98Ru through the ν p-process in various supernova progenitors based upon recent models. In particular, the ν p-process in energetic hypernovae produces a large amount of p-nuclei compared to the yield in ordinary core-collapse SNe. Because of this, the abundances of 92,94Mo and 96,98Ru in the Galaxy are significantly enhanced at [Fe/H] = 0 by the ν p-process. We find that the ν p-process in hypernovae is the main contributor to the elemental abundance of 92Mo at low metallicity [Fe/H] < −2. Our theoretical prediction of the elemental abundances in metal-poor stars becomes more consistent with observational data when the ν p-process in hypernovae is taken into account.

Slow Neutron-Capture Process: Low-Mass Asymptotic Giant Branch Stars and Presolar Silicon Carbide Grains

“…AGB models in Fig. 6 predict extremely low 92 Mo/ 96 Mo ratios for the final envelope composition because the pure s-process isotope 96 Mo is significantly overproduced by a factor of ~40 in the envelope compared to its initial abundance. A comparison of the two KADoNiS 0.3 AGB models with different initial 92 Mo abundances in Fig.…”

“…The p-process is an umbrella term for multiple nucleosynthesis processes that can produce proton-rich nuclei in the heavy mass region. So far, it has been proposed that the p-process includes gamma process in Type II core-collapse supernovae and Type Ia supernovae and neutrino-p process in Type II core-collapse supernovae (see [96] and references therein). [47,66] with the same FRUITY model but calculated with different Mo σMACS values.…”

“…[47,66] with the same FRUITY model but calculated with different Mo σMACS values. The normalization isotope is 96 Mo. Note that the FRUITY models were run in a postprocess way (see [47] for details), different from the fully coupled FRUITY models shown in Figs.…”

“…It was shown that AGB model predictions for Mo isotopes are unaffected by the two neutron sources and controlled by the adopted Mo σMACS values [97]. According to Equation (5), the ratio of 97 Mo/ 96 Mo (i.e., N 97 /N 96 ) is approximately related to σ 97 MACS/ σ 96 MACS. The p-process isotope 92 Mo is off the s-process path and is, therefore, destroyed by neutron capture during the s-process in AGB stars.…”

“…The p-process isotope 92 Mo is off the s-process path and is, therefore, destroyed by neutron capture during the s-process in AGB stars. As a result, the final 92 Mo abundance in the AGB envelope is dominantly controlled by the initially adopted 92 Mo abundance, which is poorly known due to uncertainties in modeling the GCE of p-process nuclei [96]. AGB models in Fig.…”