Dynamic auroral storms on Saturn as observed by the Hubble Space Telescope
Brown, R. H.; Baines, K. H.; Dougherty, M. K.; Kurth, W. S.; Mitchell, D. G.; Nichols, J. D.; Clarke, J. T.; Cowley, S. W. H.; Bunce, E. J.; Gérard, J. -C.; Grodent, D.; Pryor, W. R.; Crary, F. J.; Melin, H.; Grocott, A.; Stallard, T. S.; V. Badman, S.
United Kingdom, United States, Belgium
Abstract
We present observations of significant dynamics within two UV auroral storms observed on Saturn using the Hubble Space Telescope in April/May 2013. Specifically, we discuss bursts of auroral emission observed at the poleward boundary of a solar wind-induced auroral storm, propagating at ∼330% rigid corotation from near ∼01 h LT toward ∼08 h LT. We suggest that these are indicative of ongoing, bursty reconnection of lobe flux in the magnetotail, providing strong evidence that Saturn's auroral storms are caused by large-scale flux closure. We also discuss the later evolution of a similar storm and show that the emission maps to the trailing region of an energetic neutral atom enhancement. We thus identify the auroral form with the upward field-aligned continuity currents flowing into the associated partial ring current.