Tracing Turbulent Ambipolar Diffusion in Molecular Clouds

TL;DR

This paper provides observational evidence linking the difference in ion and neutral velocity dispersions to magnetic field strength, offering insights into turbulent ambipolar diffusion scales in molecular clouds.

Contribution

It demonstrates that the velocity dispersion difference between ions and neutrals correlates with magnetic field strength, advancing understanding of ambipolar diffusion in molecular clouds.

Findings

Velocity dispersion difference correlates with magnetic field strength.

Evidence supports turbulent ambipolar diffusion as a key process.

Method to estimate AD scales using ion-neutral velocity spectra.

Abstract

Though flux freezing is a good approximation frequently assumed for molecular clouds, ambipolar diffusion (AD) is inevitable at certain scales. The scale at which AD sets in can be a crucial parameter for turbulence and the star formation process. However, both observation and simulation of AD are very challenging and our knowledge of it is very limited. We proposed earlier (Li and Houde 2008) that the difference between ion and neutral velocity spectra is a signature of turbulent AD and can be used to estimate the AD scales and magnetic field strength. Here we present observational evidence showing that this difference between the velocity dispersions from coexistent ions and neutrals is indeed correlated with magnetic field strength.