Over billions of years of galactic history, a variety of stellar nucleosynthesis processes created the nuclei heavier than hydrogen and helium found in the solar system. Many of those nuclei were…

This is a $261,000 grant awarded by the National Aeronautics and Space Administration (NASA) to Clemson University's Division of Research to conduct research on the origin and history of dust grains that carried isotopes into the early solar system. The research aims to understand the initial chemical state of the solar system and how it evolved as the earliest solar system bodies formed. The project will utilize open-source computer models and codes developed by the Principal Investigator and students to study dust condensation in stellar outflows, the isotopic evolution of dust in the interstellar medium, and the implications for isotopic anomalies observed in primitive solar system samples. The research findings will contribute to NASA's fundamental science objective of understanding how the solar system formed and evolved. The grant does not have a set-aside designation.

Over billions of years of galactic history, a variety of stellar nucleosynthesis processes created the nuclei heavier than hydrogen and helium found in the solar system. Many of those nuclei were ejected from their stellar sources in the form of dust, which then cycled through the galaxy before being incorporated into the cloud that became the solar system. Along with gas, these dust grains, which carried many of the heavy nuclei into the solar nebula, served as the initial building blocks of the solar system. The processes in the early protoplanetary disk that formed planetary bodies did not completely homogenize the isotopes in the initial dust and gas building blocks of the solar system, and primitive samples and bulk meteorites built from these incompletely mixed building blocks thus retain cosmic chemical memory of the nucleosynthesis and galactic chemical evolution processes responsible for those isotopes. Cosmic chemical memory shows up in solar system samples as isotopic anomalies, that is, as deviations from the average solar system isotopic abundances. The PI proposes in this work to compare isotopic anomalies in cosmochemical samples to calculations from models of nucleosynthesis and galactic chemical evolution in order to constrain stellar processes, evolution of isotopic abundances in the interstellar medium, and the solar systems initial chemical state and early evolution. The PI will carry out this comparison by performing theoretical research and computer modeling. He will use models constructed on top of nucnet tools and nucnet projects, open source, freely available computer codes he and his students have developed, to study nucleosynthesis, stellar evolution, and galactic chemical evolution. He will compare the results of his calculations to isotopic anomalies measured in calcium aluminum rich inclusions, presolar grains, and bulk meteorites. Comparison between observed chemical memory effects with those predicted by the PIS models will yield insights and constraints on the types of processes occurring in the STARS, the interstellar medium, and the early solar system. The work will be carried out by the PI and a to be named graduate and undergraduate student, and all computer codes developed will be released as free, open source software or on a hubzero based platform that will allow them to be run directly over the web. The work will focus on the following topics. First, the PI will use the kinetic chemical condensation code he and students have written to study dust condensation in exploding STARS to gain insight into the formation of dust in a variety of stellar outflows. Second, the PI will use the open source ICE inhomogeneous chemical evolution code he and his students have developed to study the isotopic evolution of dust in the interstellar medium. The goal is to understand the potential correlated isotopic abundances in the carriers of elements into the early solar system and the consequences for isotopic anomalies observed in primitive solar system solids and bulk planetary scale bodies. The PI will focus initially on anomalies in CA, TI, CR, MO, RU, and PD, which are well established by experimental work, but will extend the work to other elements as well. The fundamental science question of research in the emerging worlds program is to understand how the solar system formed and evolved. By studying the origin and history of the dust grains that carry the isotopes into the early solar cloud and constitute the building blocks of the sun and planetary bodies, the projects proposed by the PI will contribute to our understanding of the initial chemical state of the solar system and how that state evolved as the earliest solar system bodies formed. The release of generally useful open source codes and the implementation of those codes on a hubzero based platform will foster further collaboration among NASA funded researchers and provide useful tools for public outreach.