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The effects of compositional inhomogeneities and fractal dimension on the optical properties of astrophysical dustMathis and Whiffen (1989) have recently suggested that interstellar dust particles are fluffy aggregates of submicron-size particles composed of various astronomical minerals. These dust particles should exhibit optical properties that are quite different from standard dust, characterized by spherical particles of various homogeneous mineral composition. In this paper, the discrete dipole approximation (DDA) method is used to examine the effects of chemical inhomogeneities and spatial structure on the optical properties of interstellar Mathis-Whiffen-type dust particles. The spatial structure of the dust is represented by its fractal dimension, and the chemical inhomogeneities are simulated by randomly assigning the composition of the occupied sites in the structure to be either carbon or silicate. It is found that compositional inhomogeneities are the dominant parameter affecting the shape of the 9.7 and 18 micron silicate bands. Some bands-shape variations can be attributed to the fractal dimension of the dust. The results derived here can be used to explain or constrain variations in these parameters among various astronomical objects.
Document ID
19900059264
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Bazell, David
(Applied Research Corp. Landover, MD, United States)
Dwek, Eli
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 14, 2013
Publication Date
September 1, 1990
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 360
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
90A46319
Funding Number(s)
CONTRACT_GRANT: NAS5-28771
Distribution Limits
Public
Copyright
Other

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