Presolar silicon carbide grains from a CO3 meteorite

Presolar silicon carbide (SiC) grains found in primitive meteorites can help constrain circumstellar condensation processes and nucleosynthesis in C-rich low-mass asymptotic giant branch stars and core collapse supernovae. We performed the first presolar grain chemical separation procedure on primitive CO3 meteorite Northwest Africa 7892 and identified 45 presolar SiC grains. These grains fit into the previously defined presolar SiC groups in similar proportions. We used a new secondary ion mass spectrometer (NanoSIMS XR prototype) to obtain high spatial resolution images of the grains. Three of the grains have isotopically distinct hotspots: regions 150-500 nm in diameter whose $_{}^{12}$ C/ $_{}^{13}$ C ratios differ from that of the host grain by $>5\sigma .$ Though the origin of the hotspots is unclear, these nanoscale features demonstrate the potential for new discoveries with the ultrabright ${\mathrm{Cs}}^{+}$ make it superscript source in the NanoSIMS XR prototype.

The online version contains supplementary material available at https://doi.org/10.1140/epja/s10050-026-01959-5.