Ion-Neutral Drift Velocity as a Diagnostic of Dust Growth and Magnetic Field in Star-Forming Environments

TL;DR

This study uses simulations to show how dust growth and magnetic field strength influence ion-neutral drift velocities in star-forming regions, proposing a new diagnostic method for astrophysical environments.

Contribution

The paper demonstrates that dust growth and magnetic field strength critically affect ion-neutral drift velocities, offering a novel diagnostic approach for star-forming environments.

Findings

Dust growth and magnetic fields of 200 microgauss reproduce observed drift velocities.

Ion-neutral drift velocity can diagnose dust size distribution.

Measurements on core scales are particularly informative.

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 microgauss 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.