Composite Interstellar Grains

Abstract

The composite grain is made up of a host silicate spheroid and graphite inclusions. The extinction efficiencies of the composite spheroidal grains for three axial ratios are computed using the discrete dipole approximation (DDA). The interstellar extinction curve is evaluated in the spectral region 3.40--0.10$\mu m$ using the extinction efficiencies of the composite spheroidal grains. The model extinction curves are then compared with the average observed interstellar extinction curve. We also calculate the linear polarization for the spheroidal composite grains at three orientation angles and find the wavelength of maximum polarization. Further, we estimate the volume extinction factor, an important parameter from the point of view of cosmic abundance, for the composite grain models that reproduce the average observed interstellar extinction. The estimated abundances derived from the composite grain models for both carbon and silicon are found to be lower than that are predicted by the bare silicate/graphite grain models but these values are still higher than that are implied from the recent ISM values.

11 pages, 12 figures, 5 tables To appear in 2007 MNRAS

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Cited by in corpus (10)

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• The effect of porosity of dust particles on polarization and color with special reference to comets
• Did life originate from low-temperature areas of the Universe?
• Infrared Emission from the Composite Grains: Effects of Inclusions and Porosities on the 10 and 18 $\mu m$ Features
• Composite Grains: Effects of Porosity and Inclusions on the 10$\mu$m Silicate Feature
• Composite Circumstellar Dust Grains
• A 3D Automated Classification Scheme for the TAUVEX data pipeline
• Interstellar Dust models towards some IUE stars
• Correlation among extinction efficiency and other parameters in an aggregate dust model
• Interstellar Grains: Effect of Inclusions on Extinction