Chemical enrichment of the pre-solar cloud by supernova dust grains
  The presence of short-lived radioisotopes (SLRs) in solar system meteorites
has been interpreted as evidence that the solar system was exposed to a
supernova shortly before or during its formation. Yet results from
hydrodynamical models of SLR injection into the proto-solar cloud or disc
suggest that gas-phase mixing may not be efficient enough to reproduce the
observed abundances. As an alternative, we explore the injection of SLRs via
dust grains as a way to overcome the mixing barrier. We numerically model the
interaction of a supernova remnant containing SLR-rich dust grains with a
nearby molecular cloud. The dust grains are subject to drag forces and both
thermal and non-thermal sputtering. We confirm that the expanding gas shell
stalls upon impact with the dense cloud and that gas-phase SLR injection occurs
slowly due to hydrodynamical instabilities at the cloud surface. In contrast,
dust grains of sufficient size (> 1 micron) decouple from the gas and penetrate
into the cloud within 0.1 Myr. Once inside the cloud, the dust grains are
destroyed by sputtering, releasing SLRs and rapidly enriching the dense
(potentially star-forming) regions. Our results suggest that SLR transport on
dust grains is a viable mechanism to explain SLR enrichment.
