Abstract

Weather on Other Worlds: Implications for JWST Phase Mapping of Variable Brown Dwarfs

Stanimir Metchev (University of Western Ontario)

Kendra Kellogg (UWO) Megan Tannock (UWO) Aren Heinze (Hawaii IfA)

The series of investigations under the Weather on Other Worlds program with Spitzer have shown that photospheric inhomogeneities — large-scale spot or cloud structures — are virtually ubiquitous on brown dwarfs. Continued variability monitoring is now divulging the range of characteristics of non-irradiated substellar objects, with spots now also found on planetary-mass objects. Phase mapping of rotating (variable) objects reveals longitudinal variations, while wavelength-dependent monitoring enables a vertical probe of cloud layers and of temperature-pressure profiles. Such differential approaches are effective because they measure perturbations around an otherwise constant set of atmospheric conditions. Thus, spectroscopic phase mapping allows a higher-precision determination of the 3-D atmospheric structure than is attainable by forward or inverse modelling of non-variable objects. The 0.6-28.5 micron wavelength grasp of JWST will offer unprecedented insights into brown dwarf and exoplanetary atmospheres. With brown dwarf variability science emerging mostly in the post-cryogenic Spitzer era, spectrophotometric phase mapping with JWST will for the first time probe the dominant condensate opacity source in the atmospheres of L and T type dwarfs: silicate dust clouds. We present results from optical/near-infrared spectroscopic monitoring of variable brown dwarfs that have enabled us to develop tomography tools to probe the cloud structure of brown dwarf and exoplanet atmospheres with JWST.

Talk