Gravitational instability of filamentary molecular clouds, including ambipolar diffusion

TL;DR

This paper investigates how ambipolar diffusion affects the gravitational instability and fragmentation scale of filamentary molecular clouds in magnetohydrodynamics, revealing that increased diffusion enhances instability growth.

Contribution

It introduces a linear perturbation analysis incorporating ambipolar diffusion into filament stability, providing new insights into cloud fragmentation mechanisms.

Findings

Ambipolar diffusion enhances the growth rate of unstable modes.

Increased diffusion leads to larger fragmentation scales.

Magnetic fields influence filament stability in non-ideal MHD.

Abstract

The gravitational instability of a filamentary molecular cloud in non-ideal magnetohydrodynamics is investigated. The filament is assumed to be in hydrostatic equilibrium. We add the effect of ambipolar diffusion to the filament which is threaded by an initial uniform axial magnetic field along its axis. We write down the fluid equations in cylindrical coordinates and perform linear perturbation analysis. We integrate the resultant differential equations and then derive the numerical dispersion relation. We find that, a more efficient ambipolar diffusion leads to an enhancement of the growth of the most unstable mode, and to increase of the fragmentation scale of the filament.