Cometary plasmas and the solar wind

The interaction between a comet and the solar wind has been treated extensively in the literature. Solution of the general flow problem, for example, has been considered by Ioffe (1966), Kovar and Kern (1966), and Biermann, Brosowski, and Schmidt (1967) among others. The general approach in these treatments has been that of gas dynamics. Both a shock front (on the sunward side of the comet) and a contact discontinuity are thought to form. In the present treatment, for the region interior to the contact discontinuity, an alternate approach is taken. Namely, the assumption is made that the ions moving away from the comet's nucleus are non-interacting and that these ions are specularly reflected back into the region bounded by the contact discontinuity by the solar wind's frozen-in magnetic field. A model is developed which predicts the size and shape of the contact discontinuity and the density of plasma interior to it. Results of this model agree well with observational data.