Windows into Alien Worlds: Modeling and Characterizing Substellar Atmospheres

Abstract

Atmospheres constitute the only accessible layer for observation from space, and their properties are linked to objects' formation and evolution, surface and interior processes, and habitability. Exoplanets and brown dwarfs are difficult to observe, but they provide a vast and varied data set which compliments insights gleaned from the small number of Solar System planets. This dissertation encompasses a series of studies all related to modeling, observing, and understanding substellar atmospheres. I present results from four publications and one project still in progress, as well as a full update to the opacity tables paired with the atmosphere codes used in this work: coolTLUSTY and METIS. All studies put a particular emphasis on anticipating new insights that may be gained from upcoming missions: direct imaging of mature giant exoplanet's reflecting starlight and direct imaging of young self-luminous exoplanets with the optical coronagraph on the Nancy Grace Roman Space telescope, transit spectroscopy of cloudy, tidally-locked warm exoplanets with the James Webb Space Telescope, and finally spectra of cool Y dwarfs, also a prime target for the James Webb Space Telescope.