Light scattering studies of randomly oriented polycrystalline fayalite micro particles as interstellar dust analogues

摘要

Fayalite (Fe2SiO4), the iron end-member of the olivine group, is found in various extraterrestrial environments including the interstellar medium and meteorite. Since the iron rich silicates, i.e. fayalites, are not abundantly found in earth, there has been lack of sufficient experimentation and modeling leading to the unavailability of sufficient experimental data of fayalite for comparative analyses with computations and astrophysical observations. In this work interstellar fayalite dust analogues were synthesized in the laboratory using simple chemical route. Shape and size dispersed interstellar dust analogue models for laboratory synthesized fayalite particles were developed for performing theoretical computations of light scattering parameters (e.g., angular profiles of intensity and degree of linear polarization, geometric and single-scattering albedo, asymmetry parameter and cross-sections of extinction and absorption) using discrete dipole approximation (DDA). In order to demonstrate the validity of our models, phase function and degree of linear polarization were measured using a laboratory based setup and the results were compared with DDA computed theoretical values at three wavelengths 543.5 nm, 594.5 nm and 632.5 nm respectively. (C) 2017 Elsevier Ltd. All rights reserved.