A Stormy Forecast for the Evolution of Brown Dwarfs
Trent Dupuy

Below the stellar hydrogen-fusion mass limit, temperatures drop dramatically with both mass and age. Thus brown dwarfs come to have similar temperatures as planets and provide a key benchmark for testing models of the atmospheric physics they share in common. A broad-brush view of the most prominent changes that take place over their evolution has been in place for nearly a decade, thanks to modest initial samples of parallaxes and a few dynamical masses barely breaching the hydrogen-fusion boundary. I will present results from our high-precision infrared astrometry programs that greatly expand such tests of substellar evolution. Our large sample of parallaxes from the Canada-France-Hawaii Telescope provides new perspectives on the cooling of brown dwarfs, including the discovery of a phase of rapid cloud clearing. Our Spitzer parallaxes have begun to establish the temperatures of the coldest known brown dwarfs (˜400 K) and reveal unexpected changes in the atmospheric chemistry of brown dwarfs as they approach planetary masses. Finally, I will show how new, precise dynamical masses from our Keck laser guide star adaptive optics orbit monitoring are providing unique and stringent tests of some of the most fundamental predictions of substellar evolutionary models.