Interaction of interplanetary dust particles with magnetic clouds

Abstract

Context. The interaction of the solar wind with interplanetary dust in the inner solar system appears to result in the formation of inner-source pickup ions. The flux of these ions is roughly two orders of magnitude larger than expected based on established dust particle profiles. This discrepancy can be resolved, if a population of very small (~0.02 μ m) dust particles exists in the vicinity of the Sun (within 0.2 AU). The encounter with a magnetic cloud exerts a sudden magnetic perturbation on the orbital parameters of charged interplanetary dust particles (IDPs) of sizes μ m, which may expel them from the solar system. Aims. The grains gain additional velocity components caused by the Lorentz force. Depending on the orientation of the fluxrope towards the dust grain's undisturbed orbital motion, the deflection can increase the orbital eccentricity or the inclination. Methods. The degree of orbital disturbance for each encounter is calculated numerically. Results. The “blow-out distance” can be approximated as a function of the grain radius, s , alone: $D(s)$ = 28.183$\cdot$ s – 0.308. On the other hand, the change in inclination depends on both the heliocentric distance, r , as well as the size of the grain: $I(s, r)$ = 0.124$\cdot$ r 1.814 $\cdot$ s -1.949 . The interaction of magnetic clouds with IDPs can contribute to the dust flux and acts as a sink for small dust grains.