title: The impact of an ICME on the Jovian X-ray aurora.
abstract: We report the first Jupiter X-ray observations planned to coincide with an interplanetary coronal mass ejection (ICME). At the predicted ICME arrival time, we observed a factor of ∼8 enhancement in Jupiter's X-ray aurora. Within 1.5 h of this enhancement, intense bursts of non-Io decametric radio emission occurred. Spatial, spectral, and temporal characteristics also varied between ICME arrival and another X-ray observation two days later. Gladstone et al. (2002) discovered the polar X-ray hot spot and found it pulsed with 45 min quasiperiodicity. During the ICME arrival, the hot spot expanded and exhibited two periods: 26 min periodicity from sulfur ions and 12 min periodicity from a mixture of carbon/sulfur and oxygen ions. After the ICME, the dominant period became 42 min. By comparing Vogt et al. (2011) Jovian mapping models with spectral analysis, we found that during ICME arrival at least two distinct ion populations, from Jupiter's dayside, produced the X-ray aurora. Auroras mapping to magnetospheric field lines between 50 and 70RJwere dominated by emission from precipitating sulfur ions (S7+,…,14+). Emissions mapping to closed field lines between 70 and 120RJand to open field lines were generated by a mixture of precipitating oxygen (O7+,8+) and sulfur/carbon ions, possibly implying some solar wind precipitation. We suggest that the best explanation for the X-ray hot spot is pulsed dayside reconnection perturbing magnetospheric downward currents, as proposed by Bunce et al. (2004). The auroral enhancement has different spectral, spatial, and temporal characteristics to the hot spot. By analyzing these characteristics and coincident radio emissions, we propose that the enhancement is driven directly by the ICME through Jovian magnetosphere compression and/or a large-scale dayside reconnection event.
authors.affiliation: Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Centre for Planetary Science UCL/Birkbeck London UK.
authors.forename: William R
authors.initials: WR
authors.lastname: Dunn
authors.affiliation: Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK.
authors.forename: Graziella
authors.initials: G
authors.lastname: Branduardi-Raymont
authors.affiliation: ZP12, NASA Marshall Space Flight Center Huntsville Alabama USA.
authors.forename: Ronald F
authors.initials: RF
authors.lastname: Elsner
authors.affiliation: Center for Space Physics Boston University Boston Massachusetts USA.
authors.forename: Marissa F
authors.initials: MF
authors.lastname: Vogt
authors.affiliation: LESIA, Observatoire de Paris, CNRS, UPMC Université Paris Diderot Meudon France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Lamy
authors.affiliation: Kavli Institute for Astrophysics and Space Research MIT Cambridge Massachusetts USA.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Ford
authors.affiliation: Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Centre for Planetary Science UCL/Birkbeck London UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Coates
authors.affiliation: Space Science and Engineering Division Southwest Research Institute San Antonio Texas USA.
authors.forename: G Randall
authors.initials: GR
authors.lastname: Gladstone
authors.affiliation: Department of Physics and Astronomy University of Southampton Southampton UK.
authors.forename: Caitriona M
authors.initials: CM
authors.lastname: Jackman
authors.affiliation: Department of Physics and Astronomy University of Leicester Leicester UK.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Nichols
authors.affiliation: Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK.
authors.forename: I Jonathan
authors.initials: IJ
authors.lastname: Rae
authors.affiliation: Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Space Research Institute Austrian Academy of Sciences Graz Austria.
authors.forename: Ali
authors.initials: A
authors.lastname: Varsani
authors.affiliation: Institute of Space and Astronautical Science Japan Aerospace Exploration Agency Sagamihara Japan; Nishina Center for Accelerator-Based Science RIKEN Wako Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Kimura
authors.affiliation: Department of Atmospheric, Oceanic and Space Sciences University of Michigan Ann Arbor Michigan USA.
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Hansen
authors.affiliation: Mullard Space Science Laboratory, Department of Space and Climate Physics University College London Dorking UK; Centre for Planetary Science UCL/Birkbeck London UK; Department of Atmospheric, Oceanic and Space Sciences University of Michigan Ann Arbor Michigan USA.
authors.forename: Jamie M
authors.initials: JM
authors.lastname: Jasinski
keywords: Aurora; CME; Jovian; Jupiter; Periodicity; X‐ray