The isotopic compositions and stellar sources of meteoritic graphite grains

Abstract

The isotopic compositions of interstellar graphite grains in meteorites provide a record of the stellar environments in which they formed. The grains have 12C/13C ratios that range far from the terrestrial value, as well as large variations in 14N/15N and 16O/18O, and pronounced 26Mg excesses from the decay of extinct 26AI. This isotopic variability indicates several types of stellar source, including asymptotic giant branch stars, Wolf-Rayet stars and novae. © 1993 Nature Publishing Group.