Modeling optical properties of cosmic dust grains using a distribution of hollow spheres

By Michiel Min, J. Hovenier, A. D. Koter. 2005

212 citations recorded by the source corpus.

In this paper we study the combined effects of size and shape of small solid state particles on the absorption, emission and scattering characteristics. We use the statistical approach to calculate these optical properties. In this approach the average optical properties of an ensemble of particles in random orientation are represented by the average optical properties of an ensemble of simple shapes. The validity of this approach is studied in detail for a uniform distribution of hollow spheres where the fractional volume of the central inclusion is varied. We apply the results to two different areas of interest, i) infrared spectroscopy; and ii) polarization of scattered light. The effects of particle size and shape on the optical characteristics are discussed. We compare the results using the distribution of hollow spheres with those obtained by using randomly oriented spheroids. Also we compare the results with observations and laboratory measurements. The distribution of hollow spheres is very successful in reproducing laboratory measurements of the scattering angle distribution of the degree of linear polarization for incident unpolarized light of randomly oriented irregular quartz particles. Furthermore, we show that we are able to derive the size distribution of dust grains by fitting the measured degree of linear polarization using computational result for hollow spheres. It is shown that the distribution of hollow spheres is a powerful tool for studying light scattering, absorption and emission by cosmic dust grains and in particular when large numbers of particle parameters need to be considered since the computational demand of the distribution of hollow spheres is small.

Subfields: Earth-Surface Processes, Health, Toxicology and Mutagenesis, Transportation

View Paper: https://www.semanticscholar.org/paper/e1ed6e7234883adafa54ed3cde0d96e3e17130fc

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In Earth-Surface Processes

1. Oleg Dubovik
2. Ping Yang
3. Brent N. Holben
4. J. Blum

Citations in the corpus

• Application of spheroid models to account for aerosol particle nonsphericity in remote sensing of desert dust (2006, methodology): “For example, Min et al. [2005] used a hollow-sphere model to”
• The warm gas atmosphere of the HD 100546 disk seen by Herschel - Evidence of a gas-rich, carbon-poor atmosphere? (2012, background): “The optical constants are for irregularly shaped distributions of hollow spheres (DHS, Min et al. 2005).”
• Numerical Simulation of Dust Aggregate Collisions. I. Compression and Disruption of Two-Dimensional Aggregates (2007, background): “Thermal emission properties of dust aggregates are strongly dependent on their structures (e.g., Wright 1987; Stognienko et al. 1995; Min et al. 2003, 2005, 2006).”
• Luminosities and mass-loss rates of SMC and LMC AGB stars and red supergiants (2009, methodology): “Min et al. (2005, 2007) show that a DHS with fmax= 0.7 provides a good fit to the shape of the interstellar silicate feature at 10µm, while with a value of 0.4 they can reproduce the polarisation properties of quartz measured in laboratory data.”
• Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e (2020, methodology): “For this we used cloud opacities calculated with the code by Min et al. (2005), which also makes uses of software by Toon & Ackerman (1981).”
• Size-sorting dust grains in the surface layers of protoplanetary disks (2008, unknown): “We are aware that the interpretation of the feature shape in terms of grain size is still under debate, as porosity and fractal structure of the aggregates may influence the absorption/emission cross section (Voshchinnikov et al. 2006; Min et al. 2005).”
• MILLIMETER-WAVE POLARIZATION OF PROTOPLANETARY DISKS DUE TO DUST SCATTERING (2015, background): “The low opacity index at millimeter wavelengths can be reproduced not only by changing grain size, but also by changing chemical composition (e.g., Pollack et al. 1994) or shape (e.g., Min et al. 2005).”
• c2d Spitzer IRS Spectra of Disks around T Tauri Stars. I. Silicate Emission and Grain Growth (2005, methodology): “Therefore, to simulate porous or irregularly shaped particles, we calculate opacities for continuous distributions of hollow spheres (DHS), using the statistical method described in Min et al. (2005).”
• Shadows and spirals in the protoplanetary disk HD 100453 (2016, methodology): “We consider the grains to be irregular in shape by setting the maximum volume void fraction used for the A42, page 4 of 11 distribution of hollow spheres (DHS) method to 0.8 (Min et al. 2005).”