Chemical enrichment of the pre-solar cloud by supernova dust grains

Abstract

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 µm) 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.

Hydrodynamic ablation of protoplanetary discs via supernovae

“…If sustained over the lifetime of the cluster this would mean that the stars would have had unrealistically massive disks (greater than the star's mass) at some point in the past. However, θ 1 Ori C may have switched on only ∼ 10 5 years ago (Scally & Clarke 2001), in which case it is unlikely that the combination of photoevaporation and viscous accretion will have significantly depleted the disks (Garcia 2011). This suggests that the Orion Nebula is in a relativity short-lived stage of its evolution, which is consistent with the lack of proplyd-like objects in other clusters (e.g.…”

“…It has been suggested (by e.g. Goodson et al 2016) that dust grains would be able to penetrate and be absorbed more easily into the disk. However, the abundance of dust grains in the SNR is uncertain (see e.g.…”

“…However, if the lower estimates for the amount of 60 Fe are correct, then the 60 Fe/ 26 Al ratio becomes much lower than that generated by supernovae (Gounelle & Meynet 2012). A possible resolution to this problem is suggested by Goodson et al (2016), who note that different sized dust grains are injected at different rates and if they preferentially carry different SLRs this could have a significant effect on the 60 Fe/ 26 Al ratio.…”

“…Recently Goodson et al (2016) performed three dimensional simulations of the interaction of a SNR with a large (8.8 pc), clumpy molecular cloud, including dust grains. They found that the majority of large dust grains are injected into the molecular cloud, within 0.1 Myr of the supernova explosion.…”

Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-lived Radioisotopes with a Shock Wave. V. Nonisothermal Collapse Regime

“…Oullette et al (2007Oullette et al ( , 2010 studied SN shock wave injection into the solar nebula, and found that only solid particles larger than ∼ 1 µm can be injected; smaller particles and gas in the SN shock front are unable to penetrate into the much higher density protoplanetary disk. Goodson et al (2016) performed a similar study of particle injection, but into a molecular cloud rather than a disk, and also found that particles larger than ∼ 1 µm were preferentially injected deep with the target cloud. However, analysis of Al and Fe dust grains in SN ejecta constrain their sizes to be less than 0.01 µm (Bocchio et al 2016), effectively severely limiting the value of both of these injection mechanism scenarios.…”