PHYS/ASTR Colloquium: "On Mineralogy in Substellar Clouds of Exoplanets and Brown Dwarfs" - Dr. Sarah Moran (Sagan Fellow, Space Telescope Science Institute)

San Francisco State University

Physics & Astronomy Colloquium Series

Monday, March 2, 2026

SEIC 210, 3:30 PM

Dr. Sarah Moran (Sagan Fellow, Space Telescope Science Institute)

Title: On Mineralogy in Substellar Clouds of Exoplanets and Brown Dwarfs

Abstract: High temperature clouds of silicates, salts, and other minerals can dramatically impact the observable atmospheric spectra of a variety of worlds. With the combined power of Hubble and JWST, we can characterize these materials and their influence on the climates of exoplanets and brown dwarfs. However, the laboratory data and typical modeling efforts typically used for interpretation do not fully capture the complexity of these materials. I will discuss my recent work to properly account for these complexities by considering mineral polymorphs and non-spherical cloud particle models. I will show modeling results using different SiO2 polymorphs on a hot Jupiter, an L dwarf, and a warm Neptune and how they compare to observational data. Additionally, I will demonstrate updated functionality of the open-source Virga cloud code, which now includes a simple parametrization for dynamical and optical effects of fractal aggregate particles. Properly accounting for the full chemical and physical complexity of condensate aerosol particles in substellar atmospheres will let us better use them as tracers of atmospheric conditions for worlds across the mass and temperature range.

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