Jupiter's UV auroral response to a magnetospheric compression event

TL;DR

This study uses Juno spacecraft data to analyze how Jupiter's ultraviolet aurora responds to a rare, extreme magnetospheric compression caused by a solar wind shock, revealing a sixfold increase in auroral emissions.

Contribution

It provides the first detailed case study linking an interplanetary shock to a significant auroral brightening on Jupiter using in-situ measurements.

Findings

Ultraviolet auroral emissions increased to 12 TW during the event.

The compression was caused by a predicted interplanetary shock.

Auroral brightening was directly associated with magnetospheric compression.

Abstract

The highly elliptical polar orbit of the Juno mission provides a unique opportunity to simultaneously measure the compression state of Jupiter's magnetosphere and the total power emitted by the planet's ultraviolet aurora, using a single spacecraft. This allows us to study how Jupiter's aurora respond to a compression event. In this paper, we present a case study of an extreme compression event that occurred on December 6-7 2022 when Juno was a distance of 70 R$_{J}$ from Jupiter. This extreme compression was accompanied by a very large increase in the ultraviolet auroral emissions to 12 TW, a factor of six higher than the baseline level. This event coincided with the predicted arrival of a powerful interplanetary shock, which was expected to cause the largest increase in the solar wind dynamic pressure seen thus far during the Juno mission. The simultaneous occurrence of the interplanetary shock, the extreme compression and the bright ultraviolet aurora suggests that in this case, the auroral brightening was caused by the solar wind shock compressing the magnetosphere.