title: Dynamics of protoplanetary and debris disks: turbulence, magnetic fields, and clumps

authors: A. Meredith Hughes

abstract: Dynamical processes in circumstellar disks are intimately tied to our understanding of the planet formation process.  In young systems, MRI-driven turbulence is a central aspect of planet formation theory, yet there are very few observational constraints on its magnitude and spatial distribution.  Furthermore, the geometry of magnetic fields remains elusive.  In mature systems, clumpy structure imprinted on dusty debris is thought to point the way to an otherwise unobservable class of Uranus and Neptune analogs.  I will discuss recent observational work at millimeter wavelengths that begins to untangle some of these issues.  Millimeter-wavelength polarimetry is uniquely suited for measuring magnetic field morphologies independent of geometry, while high-resolution molecular line spectroscopy is providing some of the first observational constraints on nonthermal linewidths in protoplanetary disks.  Imaging of debris disks at millimeter wavelengths probes the largest 
 accessible population of dust grains, thought to trace best the dynamical interactions with planets, and so far reveals a surprisingly smooth morphology.  I will discuss the implications of these recent observations, and emphasize the breakthroughs on the horizon with new instruments like ALMA.