Shock Waves in Space Environments.

We present results on two topics: a) The three-dimensional (3D) Hybrid Heliospheric Modeling System with Pickup Ions (HHMS-PI) simulations of shock waves and initial comparisons with ACE and Ulysses data for the Halloween 2003 solar events, including the Ulysses SWICS pickup proton densities; and b) Our analyses of Voyager 2 (V2) data near the termination shock (TS). Previously, we used our time-dependent 3D Hybrid Heliospheric Modeling System (HHMS) for magnetohydrodynamic (MHD) simulations of transient events originating on the Sun. We now have added the physics of “pickup” proton processes to these models. Interstellar neutral hydrogen flows into the heliosphere and becomes ionized by photoionization and by charge exchange with solar wind protons. These “pickup” protons cause a slowing and heating of the solar wind flow in the outer heliosphere. Both HHMS-PI and HHMS use continuous solar inputs to simulate processes that originate at the Sun. Our V2 analyses identified some elevated readings in the plasma subsystem (PLS) data. It is tempting to interpret these at face value as detections of high energy ions (HEIs) which may interact with the bulk convective plasma through a two stream instability giving rise to the observed enhanced signals in the plasma wave subsystem (PWS). [ABSTRACT FROM AUTHOR]