Ion-neutral Drift Velocity as a Diagnostic of Dust Growth and Magnetic Fields in Star-forming Environments

Abstract Recent observations have revealed that the ion-neutral drift velocity in star-forming molecular clouds and dense cores is on the order of ∼100 m s −1 . Theoretical studies have shown that, in ambipolar diffusion—the process responsible for the differential motion between ions and neutrals—the dust size distribution has a significant impact on the magnetic resistivities. In this study, we perform simulations to investigate how dust growth through accretion and coagulation affects the ion-neutral drift velocity in molecular clouds and cores. We find that, on core scales, both dust growth and a magnetic field strength of 200 μ G are required to reproduce the observed drift velocity. We suggest that measurements of ion-neutral drift velocity, particularly on core scales, may serve as a new diagnostic to constrain the dust size distribution and magnetic field strength in such environments.