Grain Physics and Rosseland Mean Opacities

Abstract

Tables of mean opacities are often used to compute the transfer of radiation in a variety of astrophysical simulations from stellar evolution models to proto-planetary disks. Often tables, such as Ferguson et al. (2005), are computed with a predetermined set of physical assumptions that may or may not be valid for a specific application. This paper explores the effects of several assumptions of grain physics on the Rosseland mean opacity in an oxygen rich environment. We find that changing the distribution of grain sizes, either the power-law exponent or the shape of the distribution, has a marginal effect on the total mean opacity. We also explore the difference in the mean opacity between solid homogenous grains and grains that are porous or conglomorations of several species. Changing the amount of grain opacity included in the mean by assuming a grain-to-gas ratio significantly affects the mean opacity, but in a predictable way.

19 pages, 6 figures, accepted for publication in ApJ

References in corpus (7)

• Dust Grain Size Distributions and Extinction in the Milky Way, LMC, and SMC
• Infrared Emission from Interstellar Dust. II. The Diffuse Interstellar Medium
• Low Temperature Opacities
• Infrared Emission from Interstellar Dust. I. Stochastic Heating of Small Grains
• Pixie Dust: The Silicate Features in the Diffuse Interstellar Medium
• Dust Grain-Size Distributions From MRN to MEM
• Modelling the optical properties of composite and porous interstellar grains

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