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