Abstract

In planetary atmospheres, the thermal, compositional, and cloud distributions vary in three dimensions, and these structures are determined by atmospheric circulation. One of the ultimate objectives for characterizing planetary atmospheres is to decipher the relationship between the formation of heterogeneous atmospheric structures and planetary properties. The growing exoplanet discoveries create exciting opportunities to test atmospheric dynamical theories with a variety of distinctive atmospheres. In this talk, I will present results from two recent papers where we use Hubble Space Telescope time-resolved spectroscopy to probe the atmospheric circulation patterns in brown dwarf companions. The first study concerns phase curve observations of close-orbit brown dwarf-white dwarf binaries. The tidally-locked and highly-irradiated brown dwarfs show substantial phase variations that constrain their day-night heat transfer processes. The second study showcases the information-rich data obtained from the highly variable brown dwarf companion VHS 1256 B. Its irregular-shaped light curves reveals the planetary-scale waves and cloud storms shaping its fast-evolving atmosphere. I will explain the procedures for mapping light curve signals into atmospheric structures. By comparing the observational results with general circulation model simulations, I will discuss the atmospheric dynamical properties of these brown dwarfs. Finally, I will briefly introduce results obtained from a new brown dwarf monitoring program using DIAFI on the Harlan J. Smith telescope and discuss how the DIAFI light curves can advance our understanding of planetary atmospheric dynamics.