Reply to Editor on RCs

Stepan Stverak

doi:10.5194/angeo-2021-10-ac1

Abstract

We tackle the Io's aurora source and topology by carrying out a set of global hybrid simulations of Io's interaction with the plasma torus under different model geometry and background conditions. Based on the simulated results, we compute the photon emission rates above the Io's surface and present the resulting images from a virtual telescope and topological maps showing the distribution of the emission sources across the moon's surface. This allows us to compare the structure of the aurora with the real observations and conclude on the different assumptions. We found a reasonable agreement with the real observations in the case of non-collisional background electron populations. From the comparison of the local magnetic field topology with model aurora structures, we also infer that an induced dipole feature is more probable to play a role in the interaction of Io with the Jovian magnetosphere. In addition we also examine the potential contribution of energetic electron beams, being observed in the Io's wake region, to the overall auroral emissions.

Highlights

The volcanism of Io is a significant matter contributor to the Jupiter’s magnetosphere
In addition we examine the potential contribution of energetic electron beams, being observed in the Io’s wake region, to the overall auroral emissions
Since all the neutral atmosphere components have similar spatial distribution, we note that local rate of any typical emission observed from Io would have similar structure and would scale according to magnitude of efficiency of given excitation reaction

Summary

Introduction

The volcanism of Io is a significant matter contributor to the Jupiter’s magnetosphere. Its strong volcanism supplies the moon’s atmosphere with volcanic material which makes the sulphur and oxygen neutrals the dominant species These neutrals get, eventually, ionized and these atmospheric particles supply Jupiter’s magnetosphere with plasma, creating dense plasma torus on the Io’s orbit. This plasma torus interacts with Jupiter’s magnetospheric magnetic field and the interactions cause 15 various features and effects within the Jupiter’s magnetosphere and in the Jupiter’s atmosphere itself. The interaction of Io’s atmosphere with the torus plasma formed by the structure of Jupiter’s magnetic field, possibly superposed with induced dipole moment of Io (Khurana et al, 2011), cause, ionization and excitation within the Io’s own atmosphere resulting in aurora emissions observed on Io (Roesler et al, 20 1999). For the calculation of electron impact excitation reactions we make similar assumptions as for electron impact ionization in Šebek et al (2019), i.e., the production rate of photons per unit time in a given volume ∆V is given as

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Conclusion