November 2
Polar Expedition: Exploring Zone-Dominated Equators and Vortex-Dominated Polar Regions on Brown Dwarfs and Directly Imaged Exoplanets
Speaker: Fuda Nguyen, University of Arizona
Abstract: Brown dwarfs, planetary-mass objects, and directly imaged exoplanets (collectively referred to as ultracool objects) possess cloudy atmospheres shaped by complex atmospheric dynamics, including large-scale circulation, vertical mixing, and disequilibrium chemistry. These processes can produce strikingly different spectral and temporal properties even among objects with similar effective temperatures. In particular, observations over the past decade have revealed puzzling viewing-angle-dependent colors, spectra, and light curves, hinting at latitudinal variations in cloud coverage.
In this talk, I will discuss these observations and explore how they can be interpreted through insights from giant-planet atmospheric dynamics, three-dimensional general circulation models, one-dimensional atmospheric models, and remote-sensing observations of Solar System planets. In particular, I will discuss (1) how brown dwarfs and directly imaged exoplanets span the atmospheric parameter space occupied by the giant planets of the Solar System; (2) what the longest TESS photometric monitoring campaign of a 1200 K ultracool object reveals about its zonal circulation and potential polar structures; (3) what JWST spectroscopic time-series observations reveal about atmospheric circulation on these worlds; and (4) how we can model the spectrophotometric signatures of different circulation features, such as atmospheric zones and polar vortices, on these giant worlds.
Host: Yoni Brande