Characterization of Directly Imaged Planets in Polarized Light
Maxwell Millar-Blanchaer
Jet Propulsion Laboratory

In the past twenty years we have discovered nearly 4000 extrasolar planets, allowing us to begin to answer fundamental questions about our place in the universe. Though currently limited to young Jupiter-mass planets and larger, direct imaging has enabled the direct characterization of exoplanet atmospheres through multi- wavelength and spectroscopic measurements using light emitted by the planets themselves. The interpretation of these measurements relies on fitting the observations to atmospheric models, that allow us to estimate some basic physical properties of these objects (e.g. effective temperature and surface gravity. However, comparisons of observed data to predictions from models have revealed that our understanding of cloud properties is incomplete and can limit more detailed studies. Polarimetry is a powerful technique for the study of clouds and has the potential to fill this understanding gap. In this talk I will provide an introduction as to how polarimetry can be used to learn more about clouds in directly imaged planets (and brown dwarfs) and I will present several instrument upgrades on the horizon that will enable polarimetric cloud studies. Finally, I will discuss the long-term direction of the field and scientific advances, such as the ability to detect nearby earth-like planets in reflected polarized light, that will be made possible by the Planetary Systems Imager, a second-generation instrument being developed for the Thirty Meter Telescope.