Porous interstellar grains |
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Authors: | M A Iatì C Cecchi-Pestellini D A Williams F Borghese P Denti R Saija S Aiello |
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Institution: | Dipartimento di Fisica della Materia e Tecnologie Fisiche Avanzate, Universitàdi Messina, Salita Sperone 31, 98166 Messina, Italy;Istituto Nazionale di Fisica della Materia, Unitádi Messina;Dipartimento di Astronomia e Scienza dello Spazio, Universitàdegli Studi di Firenze, Largo E.Fermi 5, 50125 Firenze, Italy;Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT |
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Abstract: | Recent observations of stellar composition suggest that elements in the Sun are significantly more abundant than in other stars. The reduction in the available element budget implies a drastic revision in current models of interstellar dust. Theoretical models are therefore exploring fluffy, porous physical structure for the grain material. Since a detailed exact treatment of extinction cross-sections is mandatory for a correct understanding of the nature of interstellar dust, we present a technique based on the multipole expansions of the electromagnetic field, which has proven to be general, flexible and powerful in treating scattering of light by porous, composite, arbitrarily shaped particles. The results of this study speak in favour of core–mantle structures characterized by the presence of porosities. |
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Keywords: | ISM: abundances dust extinction |
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