A new approach for modeling the dust dynamics in the near-nucleus coma Original Research Article

We describe the first step of development of a most general code for the investigation of the dust dynamics inside the gas–dust interaction region surrounding an active cometary nucleus. The code is based on a Monte Carlo approach, which allows (a) consideration of realistic, i.e., extremely complicated assumptions with respect to the dust and nucleus size, shape and composition, (b) the derivation of the dust velocity distribution at each point, an information needed for the analysis of future in situ dust samplings, and (c) allowance for all the forces acting on the grains, i.e., aerodynamical, gravitational, radiative and inertial. In the present first step, the trivial (unrealistic) assumptions of nucleus and dust grain homogeneity and sphericity are still made, and only the nucleus gravity, the aerodynamic force and the radiation pressure force are considered. The code was tested assuming a Halley-like grain mass distribution extending from 10−18 to 10−2 g, and nucleus H2O sublimation rates from 3 × 1026 to 3 × 1028 molecule/s. The results demonstrate that (1) even in this simple case, none of the preceding forces can be a priori neglected; (2) due to the combined action of these forces, a wealth of currently overlooked complex grain trajectories exist. These results are compared to the previously developed dust multi-fluid (DMF) method, thus evidencing the relative capabilities of the two methods.