2010ApJ...708.1268B

The discovery of decay products of a short-lived radioisotope (SLRI) in the Allende meteorite led to the hypothesis that a supernova shock wave transported freshly synthesized SLRI to the presolar dense cloud core, triggered its self-gravitational collapse, and injected the SLRI into the core. Previous multidimensional numerical calculations of the shock-cloud collision process showed that this hypothesis is plausible when the shock wave and dense cloud core are assumed to remain isothermal at ∼10 K, but not when compressional heating to ∼1000 K is assumed. Our two-dimensional models with the FLASH2.5 adaptive mesh refinement hydrodynamics code have shown that a 20 km/s shock front can simultaneously trigger collapse of a 1 M_☉ core and inject shock wave material, provided that cooling by molecular species such as H₂O, CO, and H₂ is included. Here, we present the results for similar calculations with shock speeds ranging from 1 km/s to 100 km/s. We find that shock speeds in the range from 5 km/s to 70 km/s are able to trigger the collapse of a 2.2 M_☉ cloud while simultaneously injecting shock wave material: lower speed shocks do not achieve injection, while higher speed shocks do not trigger sustained collapse. The calculations continue to support the shock-wave trigger hypothesis for the formation of the solar system, though the injection efficiencies in the present models are lower than desired.