The effect of porosity of dust particles on polarization and color with special reference to comets

TL;DR

This study investigates how the porosity of dust particles influences light polarization and color, using a novel algorithm to generate porous particles and applying DDA light scattering simulations, with implications for understanding cometary dust.

Contribution

The paper introduces a new algorithm to generate porous dust particles and analyzes their optical properties, highlighting the impact of porosity on polarization and color in astrophysical contexts.

Findings

Porosity significantly affects light polarization.

Porosity influences the color-extinction properties.

Implications for cometary dust observations.

Abstract

Cosmic dusts are mostly responsible for polarization of the light that we ob- serve from astrophysical objects. They also lead to color-extinction, thermal re- emission and other scattering related phenomena. Dusts are made of small particles which are characterised by their size (radius), composition (matter), and structure (morphology, including porosity). In the present work, we address the question of the role of the dust particle porosity on light polarization and color, using Discrete Dipole Approximation (DDA) light scattering code. To answer this question, we developed an algorithm to generate solid particles of arbitrary values of porosity. In brief, the model considers a given homogeneous structure made of touching dipoles. The dipoles are randomly removed one by one, such that the remaining structure remains connected. We stop the removal process when the desired poros- ity is obtained. Then we study the optical properties of the porous particle. That way, we show how the proper value of the porosity affects the polarization and color of the light scattered by these porous particles. In addition to polarization, porosity has important effects on photometric color. Considering an important application, we emphasize the possible role of the porosity of the cometary dust particles on polarization and color of the light scattered by cometary coma.