An overview of Io flux tube footprints in Jupiter's auroral ionosphere

Abstract

The influence of Io on the Jovian magnetosphere and its radio emissions has been studied for more than three decades. The electrodynamical interaction between Io and the Jovian magnetosphere results in an electric circuit that runs from Io along Jupiter's magnetic field lines and closes through the Jovian ionosphere (near 65° north and south latitude) at each foot of the Io Flux Tube (IFT). Where the particles carrying this current impact the atmosphere of Jupiter, an auroral-like spot of emission results. The first direct evidence of the IFT footprint was obtained in a near-infrared image of Jupiter's H₃⁺ emissions at 3.4 μ m in 1992. Subsequently, the IFT signature has been observed at far ultraviolet (by HST) and visible (by Galileo SSI) wavelengths. Part of the Jovian decameter radio emissions, and especially the "S-bursts", are believed to be directly related to the IFT. This paper discusses the multi-wavelength information available regarding the IFT footprints, along with relevant plasma measurements, and presents a qualitative picture of the IFT energetics and morphology.