Turbulent Action at a Distance due to Stellar Feedback in Magnetized Clouds

TL;DR

This study demonstrates that stellar feedback, through winds and magnetic waves, significantly influences turbulence in molecular clouds by transferring energy and altering the velocity spectrum, with implications for cloud dynamics.

Contribution

The paper introduces a novel analysis separating local and global feedback effects in magnetohydrodynamic simulations, highlighting the role of magnetic waves in turbulence generation.

Findings

Stellar winds transfer energy via magnetic waves, affecting turbulence.

Feedback enhances stirring motions over compressing motions.

Magnetic waves amplify feedback's impact, previously overlooked.

Abstract

A fundamental property of molecular clouds is that they are turbulent, but how this turbulence is generated and maintained is unknown. One possibility is that stars forming within the cloud regenerate turbulence via their outflows, winds and radiation ("feedback"). Disentangling motions created by feedback from the initial cloud turbulence is challenging, however. Here we confront the relationship between stellar feedback and turbulence by identifying and separating the local and global impact of stellar winds. We analyze magnetohydrodyanamic simulations in which we track wind material as it interacts with the ambient cloud. By distinguishing between launched material, gas entrained by the wind and pristine gas we show energy is transferred away from the sources via magnetic waves excited by the expanding wind shells. This action at a distance enhances the fraction of stirring motion compared to compressing motion and produces a flatter velocity power spectrum. We conclude stellar feedback accounts for significant energy transfer within molecular clouds, an impact enhanced by magnetic waves, which have previously been neglected by observations. Altogether, stellar feedback can partially offset global turbulence dissipation.