Meteoritic Molybdenum and Ruthenium Isotopic Abundances Document Nucleosynthetic p-process Components

Anomalies in isotopic abundances of Mo and Ru in solar system matter were found to document variable contributions of the nucleosynthetic s-process component. We report isotopic relations of Mo-92 versus Ru-100 in meteorites from chondritic parent bodies, iron meteorites, and achondrites that reveal deviations from expected s-process abundance variations. We show that two p-process isotopes Mo-92 and Mo-94 require the presence of distinct p-process components in meteoritic materials. The nucleosynthetic origin of abundant magic (N = 50) p-process nuclides, covering the mass range of Zr, Mo, and Ru, has long been an enigma, but contributions by several recognized pathways, including alpha and nu p-antineutrino reactions on protons, may account for the observed relatively large solar system abundances. Specific core-collapse supernovae explosive regions may carry proton-rich matter. Since Mo and Ru isotopic records in solar system matter reveal the presence of more than one nucleosynthetic p-process component, these records are expected to be helpful in documenting different explosive synthesis pathways and the implied galactic evolution of p-nuclides.

Automated summary

Anomalies in isotopic abundances of Mo and Ru in solar system matter were found to document variable contributions of the nucleosynthetic s-process component. The isotopic relationships between Mo-92 and Ru-100 in meteorites deviate from expected abundance variations, indicating the presence of distinct p-process components. The Mo and Ru isotopic records can help understand different explosive synthesis pathways and the galactic evolution of p-nuclides.