Chasing Weather on Brown Dwarfs

by Ray Jaywardhana (University of Toronto)

Wednesday 2 Jun 2010, 13:30 → 15:00 Europe/Stockholm

FA31

One of the most puzzling behaviors exhibited by cool brown dwarfs is their rapid evolution from red (J-K~2) to blue (J-K~0) near-infrared colors, accompanied by a J-band brightening, at the boundary between L and T spectral types, marking the transition from cloudy to cloud-free atmospheres. If the rapidity of this transition is caused by the fragmentation of photospheric dust clouds, or otherwise heterogeneous dust settling, then such patchy cloud coverage should give rise to photometric variability on rotational timescales. To test that scenario, we have undertaken the most comprehensive variability survey of cool brown dwarfs to date. Our J-band search has targeted ~50 objects over 60 nights at the DuPont 2.5-m telescope at Las Campanas with high cadence, high precision photometric sequences, and is complemented by follow-up observations in additional bands in order to characterize the nature of the variations. Here I will discuss our exciting first results, and their implications for the structure and dynamics of cool brown dwarf atmospheres.

Host: Alexis Brandeker

See also his other talk on Friday, on Exploring the Diversity of Extra-Solar Worlds