Energy Flows in the Jupiter-Io System

TL;DR

This paper develops a self-consistent model of Io's plasma torus, quantifying energy flows and power dissipation, and aligns well with observational data, revealing insights into Io-related energy sources and plasma dynamics.

Contribution

The paper introduces a comprehensive model incorporating mass, momentum, and energy conservation, constrained by spacecraft data, to analyze energy flows in Io's plasma torus.

Findings

Total power dissipated inside the torus is 3.6 times the power transported to Jupiter's ionosphere.

Power dissipation inside the torus is relatively uniform.

Most power transport via Birkeland current is localized near Io.

Abstract

With the laws of mass conservation, momentum conservation and energy conservation, incorporating the processes of neutral gas ionization and ion diffusion, we develop a self-consistent model for the bright ribbon --- the most prominent feature in Io's plasma torus. The model parameters are well constrained by earlier {\it in situ} observations with the Galileo and Voyager spacescrafts. Our model calculation indicates that the total power dissipated inside the torus is 3.6 times bigger than the total power transported to Jovian ionosphere via Birkeland current. The power dissipation inside the torus is relatively uniform. Most of the power transportation associated with the Birkeland current, however, is localized near the flux tube of Io. With a height-intergrated conductivity of 0.15$\,$mho in Jovian ionosphere, consistent with earlier aeronomy models, the model gives a reasonable fit to the recent observations of the FUV Io tail on Jupiter. Extra mass loading near Io is required in the model. This excess of mass injection into the plasma torus may explain the Io-correlated energy source revealed by earlier EUV observations with the Voyager spacecrafts. Further investigation of the model implications is warranted.