Probing Metal-Poor Ultracool Dwarfs Across the Galaxy with JWST Retrievals
Ember Vosmek-Park
Department of Physics & Astronomy
Faculty Supervisor: Eileen C. Gonzales
Ultracool Dwarfs (UCDs) are valuable probes of low-metallicity atmospheres, yet many metal-poor objects remain difficult to model with existing grid-based approaches. With high-quality JWST spectra from the Arcana of the Ancients program, we study the metal-poor system J1416+1348AB, both of which show spectral features that current models struggle to reproduce. Using the atmospheric retrieval code Brewster, we derive their thermal structures, chemical abundances, gas volume mixing ratios, and cloud properties, and we compare cloudy and cloud-free scenarios alongside predictions from grid models. Our goal is to improve our understanding of atmospheric modeling in the low-metallicity regime and to investigate the similarities and differences between these objects to better constrain their individual atmospheric structures and possible formation and evolutionary pathways for the J1416AB system. This work will aid in the discovery of more UCDs in ongoing and future surveys, including JWST, Euclid, the Vera C. Rubin Observatory, and the Nancy Grace Roman Space Telescope.