Collaborative Research: Galactic Archaeology from Careful Modeling of Old Stars

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The history of star formation of the entire universe is hidden in the elements making up the oldest stars in our Milky Way Galaxy. Astronomers start to unravel that history by careful observations of metal-poor (old) red giant stars. Making further progress requires numerically modeling the observations. These investigators will enhance our understanding by creating more exact models. Their work is important because in the coming years, large observational spectroscopic surveys of our Milky Way Galaxy will push the distance and age frontiers of our knowledge. The investigators plan to help analyze enormous datasets using fast, physically motivated analysis tools. They will derive the stars’ current physical parameters and chemical compositions. Currently, most models use an approximation in stellar spectral analysis, called Local Thermodynamic Equilibrium (LTE). The investigators will use more realistic, but computationally expensive, non-LTE models. The investigators will significantly improve the accuracy of derived elemental abundances found in the metal-poor red giant stars, giving us a better understanding of the history of star formation. Additionally, the project will develop opportunities for under-represented and minority K-12 students from Florida schools to undertake research using the local teaching observatory and telescopes. It will also improve diversity in astronomy through equitable and inclusive mentoring of under-represented minority undergraduate students in summer research projects at the University of Chicago.This collaborative project between the University of Florida and the University of Chicago will enable fast, homogeneous derivation of non-LTE stellar parameters and chemical abundances by implementing non-LTE in full spectrum synthesis and using machine learning techniques to efficiently emulate the non-LTE grids. The results will be applied on industrial scales to large surveys of red giant stars covering both optical and infrared wavelengths. The project will produce user-friendly, publicly available codes that allow other astronomers to apply non-LTE analyses to their spectra.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.