CAOSP abstracts, Volume: 38, No.: 3, year: 2008

Abstract: The scattering properties of composite evaporating interplanetary dust particles are analyzed. A two-component particle (usually supplying e.g. cometary dust) is considered in the form of a solid inclusion surrounded by a volatile ice shell. The processes of evaporation lead to a continuous decrease of the particle size because of ice loss, implying evolution of the optical properties of such particle. If a realistic model of the Gaussian core with ice coating is replaced by a volume equivalent homogeneous sphere, the numerical simulations become much easier and straightforward. But, the accuracy of calculation results is questionable because of hard limitations originated from Mie theory (which is strictly applicable to homogeneous spherical targets). Our results show that the Gaussian particle is a less efficient scatterer compared with the volume equivalent homogeneous sphere, especially when the particle's size is close to or larger than the wavelength of an incident radiation. The polarization features of the Gaussian particle differ from those of a homogeneous sphere. This can be an important fact in distiguishing between these two particle models. Substitution of realistically shaped and composite particles by idealized homogeneous spheres may definitely lead to a misinterpretation of measured optical data as well as to retrieval of incorrect microphysical characteristics of dust particles.

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Last update: June 16, 2008