Abundance of the Elements and Stellar Chemistry

Washington University, Saint Louis MO

Investigators

Abstract

The investigators will provide a fundamental framework for interpreting the abundances and chemical composition of the gas and dust in stellar environments. The investigations are important for many different areas in astrophysics and the chemistry of the cosmos. A major task is a large update to the reference set of abundances of the elements in our own Solar System, derived from samples of meteorites; these so-called "solar abundances" are used as a fundamental references for the study of properties of other stars and galaxies in the universe. The investigators will lead a cross-campus initiative, encouraging undergraduate students from the computer sciences to participate in this research. The results from this research are integrated into new/revised textbooks and in class materials and lectures. The female investigator serves as a role model for young women considering scientific careers. Outreach: The investigators work with the university public affairs office to issue press releases to spread results to the public; e.g., about brown dwarf weather, raining pebbles on a molten-rock planet, or about evaporating the Earth. Their investigation also supports a PhD thesis and undergraduate research. Element abundances are an important input to many chemical models in astronomy. The solar elemental abundances are commonly used as a reference when describing astronomical objects. The proposed chemistry calculations are relevant for understanding gas molecule and condensate formation in protostellar disks (with and without planetary formation); and in ejecta of evolved stars that feed dust and gas to the ISM, from which new stellar and planetary systems originate. Dying stars rarely have overall solar composition, especially not for C, N, and O, that govern redox conditions. The gas and dust chemistry strongly depends on the C/O ratio and the study aims to derive a complete set of condensation temperatures for all elements under non-solar conditions. The proposed work for chemistry at non-solar metallicities is highly relevant to planet formation models around high metallicity stars, as well as condensation around low-metallicity stars or even in dusty galaxies at high red-shift.