Self-consistent time-dependent Monte-Carlo simulations of the interaction between the heliosphere and the interstellar medium.

The Sun emits a continuous, unsteady flow of ionized plasma known as the solar wind. This plasma fills a region of space around our solar system called the heliosphere. At the same time, partially ionized plasma occupies interstellar space. The nature of the interaction between the solar wind and interstellar plasmas determines the basic structure of the heliosphere. The neutral hydrogen gas, which dominates by mass, has a great influence on this structure, which in turn determines the trajectories of cosmic rays and energetic neutral atoms. Heliospheric models exist which employ single or multiple fluids to model the neutral gas component, but it is generally accepted that these models cannot fully capture the non-Maxwellian nature of the neutrals' distribution function. To alleviate this short-coming we employ a Monte-Carlo algorithm to model neutral particle trajectories and couple this self-consistently to an MHD code which models the ionized components. We will present our latest time-dependent results and also some preliminary 3D results.