Are supernovae sources of presolar grains?

ISOTOPIC measurements¹ in chondritic meteorites have revealed that live ²⁶Al was present in the early solar system. ²⁶Al and other reported isotopic peculiarities^2-4 in the meteorite Allende could be attributable to explosive nucleosynthesis, sparking suggestions^1-8 that a nearby supernova may have contaminated the early solar nebula. One explanation for isotopic anomalies in early nebular condensates is the injection of supernova grains. An advantage of this mechanism is that it could avoid excessive dilution of the anomalies by the bulk of the nebula. We examine here the early expansion of supernovae to determine the likelihood of grain nucleation and growth.