PHYS/ASTR Colloquium: "Exploring the Diversity of Cold Worlds" - Dr. Brianna Lacy (Postdoc, U.C. Santa Cruz)

Exploring the Diversity of Cold Worlds

With JWST online, we are entering the era of cold substellar atmosphere characterization that will eventually lead us to true exoJupiter analogues. In this talk, I will present results from a forward-model analysis of a sample of ~30 late T and Y type brown dwarfs, which leverages several state-of-the art model grids and JWST spectra to constrain objects’ bulk properties. I will organize the presentation around three main questions: What do trends in disequilibrium chemistry tell us about the radiative and convective structures of late T and Y dwarf atmospheres?, What physical properties drive the diverse behavior of cold objects on the Spitzer color-magnitude diagram?, and How well do current 1D radiative-convective equilibrium model grids represent observations? I will also discuss my plans for future work investigating the impact of rotation and viewing angle in this 250 - 800 K effective temperature regime.

Dr. Brianna Lacy is a leading expert on modeling giant exoplanet and brown dwarf atmospheres. She enjoys working closely with observers to understand the physical processes shaping distant worlds and improve methods of data-model comparison. She earned her B.Sc. in Physics and Astronomy at the University of Washington in 2015 and went on to conduct her doctoral studies at Princeton University under the advising of Prof. Adam Burrows. Upon completing her Ph.D. in 2021, she spent the first two years of her 51 Pegasi b fellowship at UT Austin and is in the midst of spending the final two years at UC Santa Cruz. Upon moving to the Bay area in 2023 she also became affiliated with NASA Ames via the Bay Area Research Institute.