Irregular Magnetic Fields in Interstellar Clouds and the Linear Polarization of Starlight

Abstract

Calculations are performed for the linear polarization of starlight due to extinction by aligned dust grains when the starlight traverses a medium with irregular magnetic fields. This medium is intended to represent the optically thick components of interstellar clouds which are observed to make little, if any, contribution to the polarization of starlight. In agreement with the observations, we find that the polarization properties of the starlight---the average fractional polarization and the dispersion in position angles---can be essentially unchanged. For this, the rms of the irregular component must be greater than the average magnetic field, which in turn tends to imply that the turbulent velocities in these interstellar clouds are super-Alfvenic.

9 pages, 2 figures, AAS Latex macro, accepted by the Astrophysical Journal Letters

References in corpus (2)

• First Observations of the Magnetic Field Geometry in Pre-stellar Cores
• Irregular Magnetic Fields in Interstellar Clouds and Variations in the Observed Circular Polarization of Spectral Lines

Cited by in corpus (5)

• Tracing Magnetic Fields with Aligned Grains
• Theoretical Models of Polarized Dust Emission from Protostellar Cores
• Magnetic Fields via Polarimetry: Progress of Grain Alignment Theory
• Irregular Magnetic Fields and the Far-Infrared Polarimetry of Dust Emission from Interstellar Clouds
• Effects of mirror reflection versus diffusion anisotropy on particle acceleration in oblique shocks