Revisiting the Single-Fluid Modeling of the Solar Wind–Comet Interaction: Closer Look at the Cometosheath

Abstract

Earlier developed single fluid gas-dynamic model of solar wind–comet ionosphere interaction is applied to reveal some specifics in the morphology of the shocked "contaminated" solar wind region (cometosheath). The model is based on the Euler equations with added mass-loading, mass-loss and frictional force terms. Numerous reactions are taken into account in these terms including photoionization, charge transfer, dissociative recombination and ion-neutral frictional force. The electromagnetic terms are omitted, thus reducing the MHD single-fluid system of equations to gas-dynamic one. The used shock-fitting numerical scheme allows the separation of distinct areas formed by the considered interaction and exploration of their properties in detail. Attention is focused on the region between the shock wave and the contact surface as well as on the positions of these boundaries. Accurate examination of the distribution of density, temperature and velocity reveals spatial variations that resemble the variations registered by a number of spacecraft in the vicinity of comets. No specific comparisons with data are made at this stage. Two very first events of the Rosetta spacecraft's crossing of the magnetic cavity boundary around Comet 67P/Churyumov–Gerasimenko are discussed using a "faux-transient" application of our steady-state model.