Characterizing Exoplanets and Brown Dwarfs from the Ground and from Space

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The discovery of sub-stellar objects --both planets around other stars and "brown dwarfs" (objects with masses between stars and planets)-- rank among the most exciting advances in astrophysics in recent decades. The diversity of worlds, among the thousands already identified, is truly astounding. As searches continue to expand upon the known populations, characterization of sub-stellar worlds, through comparative studies with each other and with theoretical models, has begun in earnest. Planets caught in transit are particularly well suited for probing their atmospheres. So are brown dwarfs that are free-floating or in wide orbits around stars. I propose a multi-faceted research program, based on high-precision observations with a variety of cutting-edge instruments on the ground and in space, to advance our understanding of the nature, origins and evolution of both types of sub-stellar objects. ******With regard to exoplanets, we have already published innovative and highly-cited work on their phase variations and thermal emission, using data from frontline facilities including the Kepler space telescope. Building on our forays into transit spectroscopy with the largest telescopes on the ground, including our recent search for water vapor in a super-Earth atmosphere, we will probe the characteristics of a wide variety of transiting exoplanets from the ground and from space over the next five years. In particular, my trainees and I will be involved in guaranteed-time observations with the Canadian-built NIRISS instrument on the James Webb Space Telescope (JWST), the most powerful and the most expensive space observatory ever constructed, slated for launch in early 2019. Our targets will span the full available range of exoplanets in terms of their temperatures and masses. We will also use two new high-resolution infrared spectrographs on ground-based telescopes to characterize planets around bright stars discovered by NASA's Transiting Exoplanet Survey Satellite.******With regard to brown dwarfs, we have investigated young sub-stellar objects through deep imaging and spectroscopic surveys, found extreme brightness changes in cool brown dwarfs resulting from evolving cloud patterns in their atmospheres, and characterized a number of sub-stellar companions to stars in wide orbits. Using guaranteed time on JWST, we will probe a nearby young cluster to unprecedented depth, and investigate the frequency and properties of the lowest-mass free-floating objects. We will also utilize astrometric data from the Gaia space mission as well as ground-based spectroscopic observations to characterize nearby young brown dwarf populations. ******The overall scientific goals are to explore the remarkable diversity of sub-stellar worlds, investigate their physical characteristics and pave the way for probing atmospheres of terrestrial planets beyond our solar system. *****