The role of the magnetic field in the formation of structure in molecular clouds as revealed by Planck
Abstract
Using the polarized thermal emission from Galactic dust observed by Planck at 353 GHz, we have statistically evaluated the relative orientation of the magnetic field projected on the plane of sky and the column density structures in a sample includes ten nearby (d < 450 pc) Gould Belt molecular clouds. The relative orientation is evaluated pixel by pixel and analyzed in column density bins using the histogram of relative orientation (HRO), a statistical tool that uses the gradient to characterize the column density structures in each region.In most of the clouds in the sample, the relative orientation changes progressively from parallel or no preferred orientation in areas of the region with the lowest column density, to perpendicular in the areas with the highest column density. This trend in relative orientation is comparable to the signature of Alfvénic and sub-Alfvénic turbulence found in simulations of magnetohydrodynamic (MHD) turbulence in molecular clouds.We compare this trend in relative orientation to the magnetic field strength estimates obtained using the Chandrasekhar-Fermi technique and discuss how the Planck polarization observations lead to the integration of the magnetic fields to the general picture of molecular cloud formation and evolution.
- Publication:
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American Astronomical Society Meeting Abstracts #225
- Pub Date:
- January 2015
- Bibcode:
- 2015AAS...22510906S