Name/Affiliation: Hao Yang, Daniel Apai, and the Extrasolar Storms Team (University of Arizona)
New Insights into Cloud Properties of L Dwarf Atmospheres
At effective temperatures between ~1400 K and ~2000 K, L-type brown dwarfs have significant cloud coverage in their atmospheres. The physical and chemical characteristics of these condensate clouds are essential to our understanding of the ultracool atmospheres of brown dwarfs and giant planets. We present analysis of HST WFC3 G141 grism spectra of two L dwarfs, which are the first results from the Extrasolar Storms program. The time-resolved spectroscopic data allow us to study the evolution of their light curves at multiple wavelengths and on timescales ranging from a few hours to a few weeks, probing cloud properties at different pressure levels and different latitudes and providing constraints for atmospheric models of these ultracool objects.