Optical properties of interstellar grain aggregates

We computed, through the transition matrix method, the optical properties of cosmic dust grains modelled as aggregates (clusters) of spheres with a Gaussian-like size distribution function. The calculation is performed without resorting to any approximation and with a computational effort that is noticeably lighter than the one required by other methods. Our results show that particle clustering produces an enhancement in the extinction and radiation pressure cross-sections per unit mass. These results might help in the identification of sustainable structures for dust grains in the typical physical and chemical conditions of the diffuse interstellar medium.