Accretion and Diffusion Timescales in Sheets and Filaments

TL;DR

This paper compares accretion and magnetic diffusion timescales in star-forming clouds, concluding that rapid accretion makes diffusion processes unlikely to control core and star formation.

Contribution

It provides a comparative analysis showing that accretion timescales are much shorter than diffusion timescales, challenging the role of diffusion in star formation.

Findings

Accretion timescales are at least an order of magnitude shorter than diffusion timescales.

Dense clouds become supercritical primarily due to rapid mass accretion.

Diffusion processes are unlikely to dominate core and star formation dynamics.

Abstract

A comparison of accretion and (turbulent) magnetic diffusion timescales for sheets and filaments demonstrates that dense star-forming clouds generally will -- under realistic conditions -- become supercritical due to mass accretion on timescales at least an order of magnitude shorter than ambipolar and/or turbulent diffusion timescales. Thus, ambipolar or turbulent diffusion -- while present -- is unlikely to control the formation of cores and stars.