Modelling interstellar extinction and polarization with spheroidal grains

Abstract

We calculate the wavelength dependence of the ratio of the linear polarization degree to extinction (polarizing efficiency) $P(\lambda )/A(\lambda )$ from the ultraviolet to near-infrared. The prolate and oblate particles with aspect ratios from $a/b=1.1$ up to 10 are assumed to be rotating and partially aligned with the mechanism of paramagnetic relaxation (Davis--Greenstein). Size/shape/orientation effects are analyzed. It is found that the wavelength dependence of $P(\lambda )/A(\lambda )$ is mainly determined by the particle composition and size whereas the values of $P(\lambda )/A(\lambda )$ depend on the particle shape, degree and direction of alignment.

13 pages, 9 figures, aacepted for publication in Journal of Quantitative Spectroscopy & Radiative Transfer (special issue, X Conference on Electromagnetic & Light Scattering)

References in corpus (6)

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• Tracing Magnetic Fields with Aligned Grains
• Ultraviolet Extinction Properties in the Milky Way
• Dust extinction and absorption: the challenge of porous grains
• Extinction and polarization of radiation by absorbing spheroids: shape/size effects and benchmark results
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