Aurorae, Clouds or Magnetic Spots? Disentangling drivers of variability in three early L-Dwarfs.

Brown dwarfs provide unique insights into exometeorology - weather on extrasolar objects. They act as powerful analogs to directly imaged exoplanets, due to their similar position on colour-magnitude diagrams. They provide a wealth of information as to how both of these substellar populations form and evolve as they can be observed far easier than directly imaged exoplanets. This study investigates the spectroscopic variability of three early L-type brown dwarfs, 2M0036+18, 2M1721+33 and 2M1906+40, using a novel approach of simultaneous observations from HST/WFC3 at near-IR wavelengths and the VLA in the radio (4-12 GHz). Early L-Dwarfs are especially interesting as they are at the right temperature to allow a number of processes to occur that are not possible at other spectral types including any one of, or a combination of, aurorae, clouds and magnetic spots. This allows different insights into the atmospheric processes in giant extrasolar worlds. We use the HST data to distinguish between the various drivers of variability and potentially detect auroral activity in the near-IR for the first time. 2M0036+18 is a known auroral emitter in the radio, while 2M1721+33's variability is primarily due to condensate clouds. The final case however, 2M1906+40, has ambiguous behaviour. All three objects show significant variability in the HST observations and we aim to disentangle the drivers of variability in each object by analysing their unique signatures of variability.+