Speaker: Brittany Miles
Affiliation: University of Arizona
Date: Tuesday, April 7, 2026
Time: 3:30PM
Location: 3853 Slichter Hall
Abstract
Brown dwarfs are high-quality testing grounds for atmospheric models and optimizing requirements for exoplanet-focused instrumentation. Brown dwarfs have similar atmospheric physics and chemistry to gas giant exoplanets, but are much easier to observe because they do not suffer from host star obscuration. I will discuss the importance of mid-infrared wavelengths and needed development to understanding planetary atmospheres in the JWST and the ELT-era. First, I will share the results of a JWST program studying WISE 0855 (280K), the coldest known brown dwarf and the best analog for studying processes that also occur on gas giant planets within our Solar System. We present high SNR (80 – 100), medium resolution (R ∼1000), time-series JWST/NIRSpec spectra of WISE 0855. Our observations span 11 hours with 15-minute pointings covering 2.87–5.27 microns. The dominant time-variable feature is carbon monoxide (CO) gas absorption, producing modulations in its band strength with peak-to-peak amplitudes of 8%. We discuss the changes in CO in the context of other expected disequilibrium species such as phosphine and carbon dioxide. Using atmospheric and structural models, we find that the changes in CO and temperature must originate from distinct surface features and water clouds on WISE 0855. Second, I will share development for a third generation instrument for the Large Binocular Telescope.