CAOSP abstracts, Volume: 37, No.: 1, year: 2007

Abstract: The paper focuses on temperature behaviour of material optical properties, which may play an important role also in dust dynamics. In particular, the study deals with efficiency factors for scattering Q_sca, extinction Q_ext, and radiation pressure Q_pr, and with asymmetry parameter < cos >. Some constituents of composite particles (like amorphous carbon) may exhibit non-negligible temperature dependence of the refractive index, and thus certainly change orbital evolution of small interplanetary dust particles. Such temperature effect was unknown until now, and brings a novelty into modelling of dust dynamics.

Spectral and integral optical properties of dust grains are discussed in more detail, and attention is paid to their dependence on heliocentric distance. It is shown that imaginary part of complex refractive index of amorphous silicon and amorphous carbon particles changes markedly with distance from the Sun. Nevertheless, the particles with sizes larger than 1.5 µm behave almost independently of temperature in the outer parts of Earth's orbit. But, the submicron-sized and small micron-sized particles with temperature dependent dielectric function are evolutionary affected when they move at trajectories with close approaches to the Sun (i.e. when the perihelion distance of the orbit is less than ≈ 1 AU). The optical properties of particles with sizes less than 1 µm react on temperature variation quite efficiently.