Following the Molecular History of Stellar Ejecta: Combining Observations with Laboratory Spectroscopy and Imaging

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Mass loss from stars in the late stages of evolution is a major avenue by which the interstellar medium gets enriched in gas, dust, and heavy elements. This research project will investigate the nature of the material ejected by evolved stars and planetary nebulae. Results from the study will allow astronomers to understand how the physical and chemical properties of stars in late stages of evolution influence the lifecycle of material in the interstellar medium. This project will train graduate and undergraduate students, including ones from groups that are underrepresented in science, in advanced techniques of radio astronomy and laboratory astrophysics research. The research team will undertake a combined program of astronomical observations, laboratory experiments, and chemical modeling to explore the nature of stellar ejecta in the gas phase and in dust grains, and its impact on the diffuse interstellar medium. They will conduct molecular spectral line observations of circumstellar envelopes and planetary nebulae using ground-based single-aperture and interferometric radio telescopes. To complement and guide the observations, they will measure laboratory rotational spectra of metal-bearing molecules postulated to be important in carbon-rich and oxygen-rich envelopes of evolved stars. They will perform transmission electron microscopic imaging of carbon and silicate dust grains extracted from meteorites to investigate the relationship between metallic and non-metallic constituents of the grains, and they will perform quantum chemical calculations of dust destruction by ultraviolet radiation and shocks characteristic of planetary nebulae.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.