Brown dwarfs are sub-stellar objects that occupy the region of parameter space between gas giant planets, like Jupiter, and the smallest bona fide stars. Since brown dwarfs never achieve sustained core hydrogen fusion, they are destined to cool over cosmic timescales from thousands to hundreds of degrees Kelvin. Observations and models of these strange worlds reveal hydrogen-dominated atmospheres with a variety of trace molecular species, as well as metal, dust, and salt condensates.
Recent surveys and targeted observations have revealed that a substantial fraction of brown dwarfs have a brightness that varies in time, with some variations as large as 30% at certain wavelengths. In this presentation, Dr. Robinson will review the atmospheric physics of brown dwarfs and the current state of variability observations, and he will discuss the various processes that likely cause brown dwarf variability, which include dynamical effects, temporally- and spatially-varying clouds, and associated atmospheric temperature fluctuations.
