Journal Article

Criteria for mixing rules application for inhomogeneous astrophysical grains

N. Maron and O. Maron

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 391, issue 2, pages 738-764
Published in print December 2008 | ISSN: 0035-8711
Published online November 2008 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.13908.x
Criteria for mixing rules application for inhomogeneous astrophysical grains

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The analysis presented in this paper verifies which of the mixing rules are best for real components of interstellar dust in possible wide range of wavelengths. The Discrete Dipole Approximation (DDA) method with elements of different components with various volume fractions has been used. We have considered six materials: ice, amorphous carbon, graphite, SiC, silicates and iron; and the following mixing rules: Maxwell-Garnett, Bruggeman, Looyenga, Hanay and Lichtenecker, which must satisfy rigorous bounds. The porous materials have also been considered. We have assumed simplified spatial distribution, shape and size of inclusions. The criteria given by Draine have been used to determine the range of wavelengths for the considered mixtures in order to calculate the Qext using the DDA. From all the chosen mixing rules for the examined materials in majority of cases (13 out of 20), the best results have been obtained using the Lichtenecker mixing rule. In five cases, this rule is better for some volume fraction of inclusions.

Keywords: dust, extinction; ISM: general

Journal Article.  5673 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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