Production of Mo and Ru Isotopes in Neutrino-driven Winds: Implications for Solar Abundances and Presolar Grains

The origin of the so-called p-isotopes Mo-92,Mo-94 and Ru-96,Ru-98 in the solar system remains a mystery, as several astrophysical scenarios fail to account for them. In addition, data on presolar silicon carbide grains of type X (SiC X) exhibit peculiar Mo patterns, especially for Mo-95,Mo-97. We examine the production of Mo and Ru isotopes in neutrino-driven winds associated with core-collapse supernovae (CCSNe) over a wide range of conditions. We find that proton-rich winds can make dominant contributions to the solar abundance of Ru-98 and significant contributions to those of Ru-96, Mo-92, and Mo-94. In contrast, neutron-rich winds make negligible contributions to the solar abundances of Mo-92,Mo-94 and cannot produce Ru-96,Ru-98, whereas the early ejecta of CCSNe can make dominant contributions to the solar abundance of Mo-92. Furthermore, we show that some neutron-rich winds can account for the peculiar Mo patterns in SiC X grains. Our results can be generalized if conditions similar to those studied here are also obtained for other types of ejecta in either CCSNe or neutron star mergers.