Simultaneous Triggered Collapse of the Presolar Dense Cloud Core and Injection of Short-Lived Radioisotopes by a Supernova Shock Wave

TL;DR

This study demonstrates through advanced hydrodynamic simulations that a supernova shock wave can both trigger the collapse of a presolar cloud core and inject short-lived radioisotopes, supporting the supernova trigger hypothesis for solar system formation.

Contribution

First simulation showing simultaneous cloud collapse and isotope injection with realistic cooling, validating the supernova trigger hypothesis.

Findings

A 20 km/sec shock can trigger collapse of a 1 solar mass cloud.

Cooling by molecular species is crucial for realistic collapse and injection.

Supernova shock wave is a plausible source of early solar system radioisotopes.

Abstract

Cosmochemical evidence for the existence of short-lived radioisotopes (SLRI) such as $^{26}$Al and $^{60}$Fe at the time of the formation of primitive meteorites requires that these isotopes were synthesized in a massive star and then incorporated into chondrites within $\sim 10^6$ yr. A supernova shock wave has long been hypothesized to have transported the SLRI to the presolar dense cloud core, triggered cloud collapse, and injected the isotopes. Previous numerical calculations have shown that this scenario is plausible when the shock wave and dense cloud core are assumed to be isothermal at $\sim 10$ K, but not when compressional heating to $\sim 1000$ K is assumed. We show here for the first time that when calculated with the FLASH2.5 adaptive mesh refinement (AMR) hydrodynamics code, a 20 km/sec shock wave can indeed trigger the collapse of a 1 $M_\odot$ cloud while simultaneously injecting shock wave isotopes into the collapsing cloud, provided that cooling by molecular species such as H$_2$O, CO$_2$, and H$_2$ is included. These calculations imply that the supernova trigger hypothesis is the most likely mechanism for delivering the SLRI present during the formation of the solar system.