Physics Colloquium: Identifying Sources of Reflected Light in Unresolved Exoplanet Systems

Physics Colloquium
Identifying Sources of Reflected Light in Unresolved Exoplanet Systems

Dr. Kimberly Bott
Research Scientist
SETI Institute

Abstract:
Exoplanets are complex, with spatially varying surfaces and condensate distributions. While traditional studies of reflectance and transmission can provide clues about the nature of their atmospheres and surfaces, degeneracies and limitations remain. Clouds can obscure low altitude chemical abundances, and high polar albedo or equatorial clouds can mimic ocean glint. Furthermore, many planetary reflectance phase curve analyses do not consider the non-Lambertian nature of the condensates and surfaces. Using polarimetry (measure of the orientation of the electric field of reflected light) and cutting-edge reflectance characterization, we seek to diminish these degeneracies, allowing for the characterization of potentially habitable worlds. In this talk I provide the context of polarimetric and reflectance characterization from my own work and more broadly. I relate this to projects on hot Jupiter polarized reflectance and improved predictions for asymmetric phase curves from heterogeneous planets of all sizes. The recent and ongoing expansion of two of the most capable radiative transfer solvers in the world by my research group allows us to accurately represent complex heterogeneous worlds. Validations of our polarized radiative transfer codes with Earth, Venus, and icy moon observations, show that using these new models with contemporary observational data is sensitive to biosignature gases, ocean glint, vegetation, condensate species and phase, and disk heterogeneities (polar haze/vortex, ice caps, continents, etc.). This provides a complementary means to validate habitability metrics and biosignatures, and a route to map unresolved planets in a broader array of scenarios. Predictions aiding future telescope imaging and phase curve observations show how the methods may allow us to map worlds and distinguish between condensates and surfaces. I show the steps in the path forward to mapping and more reliably characterizing exoplanets.

Bio:
Dr. Kim Bott is an expert in planetary reflectance and polarization as applied to studies of habitability, astrobiology, and planetary characterization. She is currently a Research Scientist at the SETI Institute and Science PI of the NExSS Terrestrial Polarization Team. Previously, she was an Assistant Researcher at University of California, Riverside, and previous to that, a Postdoctoral Scholar at the University of Washington. Her PhD is from the University of New South Wales on the "Polarimetry of hot Jupiter Systems and Radiative Transfer Models of Planetary Atmospheres.

Intended Audience:
All are Welcome!

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