  The process of planet conglomeration, which primarily unfolds in a
geometrically thin disk of gas and dust, is often accompanied by dynamical
excitation of the forming planets and planetesimals. The ensuing orbital
crossing can lead to large-scale collisional fragmentation, populating the
system with icy and rocky debris. In a gaseous nebula, such leftover solid
matter tends to spiral down towards the host star due to aerodynamic drag.
Along the way, the inward drifting debris can encounter planets and
gravitationally couple to them via mean-motion resonances, sapping them of
their orbital energy and causing them to migrate. Here, we develop a simple
theory for this migration mechanism, which we call "Aero-Resonant Migration"
(ARM), in which small planetesimals ($10\,$m $\lesssim s \lesssim 10\,$km)
undergo orbital decay due to aerodynamic drag and resonantly shepherd planets
ahead of them. Using a combination of analytical calculations and numerical
experiments, we show that ARM is a robust migration mechanism, able to
significantly transport planets on timescales $\lesssim1$ Myr, and present
simple formulae for the ARM rate.
