Composite Circumstellar Dust Grains

TL;DR

This paper models the absorption efficiencies of composite circumstellar dust grains with various inclusions and porosities, comparing theoretical predictions with observed infrared emissions from stars to infer dust properties.

Contribution

It introduces detailed calculations of absorption efficiencies for composite and porous dust grains, linking theoretical models with observational infrared data.

Findings

Absorption profiles vary with inclusion volume fractions.

Peak absorption wavelengths shift with grain composition.

Infrared flux modeling constrains dust grain properties.

Abstract

We calculate the absorption efficiencies of composite silicate grains with inclusions of graphite and silicon carbide in the spectral range 5--25$\rm \mu m$. We study the variation in absorption profiles with volume fractions of inclusions. In particular we study the variation in the wavelength of peak absorption at 10 and 18$\rm \mu m$. We also study the variation of the absorption of porous silicate grains. We use the absorption efficiencies to calculate the infrared flux at various dust temperatures and compare with the observed infrared emission flux from the circumstellar dust around some M-Type \& AGB stars obtained from IRAS and a few stars from Spitzer satellite. We interpret the observed data in terms of the circumstellar dust grain sizes; shape; composition and dust temperature.