Dartmouth Events

Abstract: From individual planetary systems to the Milky Way’s structure, stars are the linchpin connecting astrophysical scales. In this thesis, I leverage large stellar surveys to investigate how the Galaxy’s dynamical and chemical history shapes planet formation and evolution. (I) I developed an automated pipeline to measure stellar rotation periods in TESS light curves, enabling rotation-based ages for thousands of stars. Applying it to stars on eccentric Galactic orbits revealed unexpectedly young populations in dynamically old regions. These rotationally young stars place new constraints on when the Milky Way's spiral arms last passed through the solar neighborhood. (II) The Sun’s depletion in refractory (heat-resistant) elements relative to its peers has long been attributed to planet formation. Using data-driven abundance measurements for thousands of Sun-like stars, I show that this pattern is not planet-driven, but instead reflects the Galaxy’s chemical enrichment history. (III) Finally, I re-examined reported excesses of hot Jupiter planets in clustered stellar environments. I show that these trends arise naturally from the giant planet–metallicity correlation manifesting differently across the Galaxy’s thin- and thick-disk populations, without requiring additional planet formation pathways. Together, this work demonstrates how disentangling stellar, Galactic, and planetary processes reshapes our understanding of each.