Professor Jeremie Lasue

Light scattering is a powerful tool to determine the physical properties of astronomical dust in a variety of environments. It has typically been used to study interstellar as well as interplanetary dust particles. From the phase functions in intensity and polarization, constraints on size, shape, size distribution and optical indices of the dust particles may be inferred. Our team in France has participated in observations of light scattering by the small bodies of the solar system, such as comets and asteroids, and developed experimental (e.g. microgravity and microwave analogs) and numerical simulations to interpret these observations in terms of the dust particles physical properties. The light scattering observed significantly departs from the spherical Mie scattering model, the dust articles being often irregular with indices corresponding to materials ranging from silicates to absorbing organics. The talk will review the current status of such studies in the wake of the results from the international Rosetta space mission to comet 67P/Churyumov-Gerasimenko. The Rosetta in situ measurements have demonstrated the fractal shape of the cometary dust particles, down to the sub-micrometer scale, and that their composition is dominated by organics compounds. Additional work currently on-going to relate the light scattering properties of cometary dust, the zodiacal light, protoplanetary disks and debris disks will be highlighted. Perspectives for future collaborations, observations, simulations and new objects of interest will be outlined.