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K. W. Davis, M. D. Leising (Clemson University)
Short-lived radionuclides with half-lives of order 3.7 to .10 Myr appear to have been present and live with abundances higher than background ISM levels during the solar system's formation. Their lifetimes are short compared to the freefall time of the presolar cloud, especially given the time necessary to transport these radionuclides from their creation site to the solar origin site. A SN event has been hypothesized as both the generator of the radionuclides and a trigger to initiate rapid collapse of the presolar cloud. In this model the SN ejecta carries the radionuclides to the solar formation site. This scenario has been well studied via the interaction of a shock with a hypothetical presolar cloud. However, the material of the shock is not the ejecta itself, but the material that lies between the SN and the cloud. Given that low mass stars can often form from dense cores in larger molecular clouds the presolar cloud may have been protected by less dense material surrounding the dense core that became the solar system. The parameters that may affect the possibility of injection are varied, but include, the distance of the cloud from the SN, the ratios of densities in the cloud and the ambient medium, and the thermodynamic properties of the gases in question. We use Zeus-2d to explore the effect these parameters have on the possibility of radionuclide injection, having modified it to include cooling and track the supernova ejecta explicitly.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.