Fractal signatures in analogs of interplanetary dust particles

- We analyze the morphology of cosmic dust aggregates using a structure factor technique.
- These aggregates are mass fractals with a fractal dimension of −1.75.
- The same fractal dimension (−1.75) is found for diffusion limited aggregation aggregates.
- Laboratory analogs of cosmic dust are thus formed by an aggregation of small particles.

Interplanetary dust particles (IDPs) are an important constituent of the earth׳s stratosphere, interstellar and interplanetary medium, cometary comae and tails, etc. Their physical and optical characteristics are significantly influenced by the morphology of silicate aggregates which form the core in IDPs. In this paper we reinterpret scattering data from laboratory analogs of cosmic silicate aggregates created by Volten et al. (2007) [1] to extract their morphological features. By evaluating the structure factor, we find that the aggregates are mass fractals with a mass fractal dimension dm≃1.75. The same fractal dimension also characterizes clusters obtained from diffusion limited aggregation (DLA). This suggests that the analogs are formed by an irreversible aggregation of stochastically transported silicate particles.