The impact of an ICME on the Jovian X-ray aurora

William R. Dunn, Graziella Branduardi-Raymont, Ronald F. Elsner, Marissa F. Vogt, Laurent Lamy, Peter G. Ford, Andrew J. Coates, G. Randall Gladstone, Caitriona M. Jackman, Jonathan D. Nichols, I. Jonathan Rae, Ali Varsani, Tomoki Kimura, Kenneth C. Hansen, Jamie M. Jasinski

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21 Citations (Scopus)

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 70 RJ were dominated by emission from precipitating sulfur ions (S7+,...,14+). Emissions mapping to closed field lines between 70 and 120 RJ and 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.

Original languageEnglish
Pages (from-to)2274-2307
Number of pages34
JournalJournal of Geophysical Research A: Space Physics
Volume121
Issue number3
DOIs
Publication statusPublished - 2016 Mar 1

Keywords

  • Aurora
  • CME
  • Jovian
  • Jupiter
  • Periodicity
  • X-ray

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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    Dunn, W. R., Branduardi-Raymont, G., Elsner, R. F., Vogt, M. F., Lamy, L., Ford, P. G., Coates, A. J., Gladstone, G. R., Jackman, C. M., Nichols, J. D., Rae, I. J., Varsani, A., Kimura, T., Hansen, K. C., & Jasinski, J. M. (2016). The impact of an ICME on the Jovian X-ray aurora. Journal of Geophysical Research A: Space Physics, 121(3), 2274-2307. https://doi.org/10.1002/2015JA021888