Solar Nebula Heterogeneity in p-Process Samarium and Neodymium Isotopes

Bulk carbonaceous chondrites display a deficit of ∼100 parts per million (ppm) in^{144}\text{Sm}$with respect to other meteorites and terrestrial standards, leading to a decrease in their^{142}\text{Nd}/^{144}\text{Nd}$ratios by ∼11 ppm. The data require that samarium and neodymium isotopes produced by the p process associated with photodisintegration reactions in supernovae were heterogeneously distributed in the solar nebula. Other samarium and neodymium isotopes produced by rapid neutron capture (r process) in supernovae and by slow neutron capture (s process) in red giants were homogeneously distributed. The supernovae sources supplying the p- and r-process nuclides to the solar nebula were thus disconnected or only weakly connected.