A Tale of Two Dwarfs: Unveiling J1416+1348 B with JWST
Efrain Alvarado III, Ember Anastasia Vosmek-Park
Department of Physics & Astronomy
Faculty Supervisor: Eileen C. Gonzales
Ultracool Dwarfs (UCDs) are stars and brown dwarfs with effective temperatures below 3000 K, masses around 0.1 solar masses, and spectral types spanning late M, L, T, and Y (Kirkpatrick 2005). Metallicity plays a crucial role in their atmospheres, formation, and evolution. While most UCDs are observed in the Solar Neighborhood, the James Webb Space Telescope (JWST) now allows us to study more distant objects across the Galaxy. This provides new opportunities to investigate the Milky Way's early metal-poor regions, offering insights into early star formation and chemical evolution. Understanding the physical properties of metal-poor UCDs remains challenging due to limited data and atmospheric models. However, with high-quality JWST data from the Arcana of the Ancients project, we can use the atmospheric retrieval code Brewster to derive their atmospheric structures and identify sources of opacity. Brewster is particularly well-suited for low-metallicity atmospheres, enabling constraints on chemical and gas abundances, thermal profiles, gas volume mixing ratios, and cloud properties. This approach provides a far more detailed analysis than traditional self-consistent one-dimensional radiative-convective equilibrium models (grid models) such as ELF OWL, SAND, LOWZ, and others. This study focuses on the atmospheric retrieval of J1416+1348 B, a T subdwarf in the only known L+T binary system, using high-resolution NIRSpec G395H data and comparing it to a forward model grid. Ultimately, 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.