Jovian magnetospheric neutral wind and auroral precipitation flux

Abstract

We propose a mechanism for the transport of energy from the rotation of Jupiter into the heavy ions whose precipitation into the atmosphere is responsible for the intense ultraviolet aurora. The process involves charge exchange of heavy ions in the Io torus, their flight to the outer magnetosphere as neutrals, and their reionization in a region where the pickup magnetic moment is large. The particles diffuse back inward adiabatically and are precipitated at 9 RJ with an energy exceeding 10 keV/nucleon. A field and flow model based on Voyager observations is used that defines a source region extending from 32 RJ to 80 RJ on the nightside. This region is capable of delivering 4×1013 W of power to the auroral region, well within the realm of the power required by observations. We also demonstrate that this mechanism provides a neutral planetary wind from Jupiter. The predicted wind will consist of two beams: one intense (5×1028 s−1) at 25 eV/nucleon and the other tenuous (1×1025 s−1) at 600 eV/nucleon and above. These neutral particles will appear as a suprathermal heavy ion component in the solar wind.