Young Gas-Giant Planets and their Brown Dwarf Cousins
Mike Liu



Direct detection is rapidly becoming a key method to study extrasolar planets, thanks to adaptive optics on largest ground-based telescopes. Akin to the early growth of radial velocity and transit studies, the first direct discoveries have revealed a surprising diversity in the exoplanet population. I discuss how these initial results have challenged our conceptions of gas-giant planet formation and properties, including the long-cherished analogy with higher mass brown dwarfs. To move forward with well-defined samples and demographics, I describe the design and results of the Gemini NICI Planet-Finding Campaign, the largest, most sensitive imaging survey to date for young gas-giant exoplanets and brown dwarfs. Finally, I discuss how our understanding of these low-mass substellar objects in the inner few arcseconds around bright stars can be advanced by wide-field surveys that mine the entire sky.