THE MAGNETOSHEATH OF NEPTUNE - MODELS AND OBSERVATIONS

This paper gives a complete overview of the plasma and magnetic field in the magnetosheath of Neptune. A more sophisticated method is used t o reanalyze the plasma data. This method provides better values of pla sma density, velocity, and temperature in the magnetosheath both inbou nd and outbound from the planet than published previously. The data ar e compared to results obtained from a gasdynamic model of flow around a planetary magnetosphere. Agreement of theory and data is good for so me parameters and poor for others. We show that some discrepancies bet ween the model predictions and observations may be due to changes in t he solar wind parameters. The model results and data are used to check the hypothesis that Voyager encountered the high-latitude plasma mant le downstream from Neptune. The deviations of the data from the model results in this region are consistent with those expected for a mantle crossing, with the exception of the plasma temperature which decrease s in one crossing and increases in the other. This may indicate that o ur knowledge of the nature of the mantle-magnetosheath boundary is not complete.