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Mapping the electron energy in Jupiter's aurora: Hubble spectral observations
Bonfond, B.; Clarke, J. T.; Waite, J. H. +6 more
Far ultraviolet spectral observations have been made with the Hubble Space Telescope in the time-tag mode using the Space Telescope Imaging Spectrograph (STIS) long slit. The telescope was slewed in such a way that the slit projection scanned from above the polar limb down to midlatitudes, allowing us to build up the first spectral maps of the FUV…
Jupiter's equatorward auroral features: Possible signatures of magnetospheric injections
Bonfond, B.; Gérard, J. -C.; Grodent, D. +2 more
The present study investigates the characteristics of ultraviolet auroral features located equatorward of the main emission appearing in Hubble Space Telescope images of the northern and southern Jovian hemispheres obtained in 2000-2007. On average, one feature is observed every day, but several auroral structures are occasionally seen over a wide…
Saturn's dayside ultraviolet auroras: Evidence for morphological dependence on the direction of the upstream interplanetary magnetic field
Lewis, G. R.; Dougherty, M. K.; Alexeev, I. I. +6 more
We examine a unique data set from seven Hubble Space Telescope (HST) "visits" that imaged Saturn's northern dayside ultraviolet emissions exhibiting usual circumpolar "auroral oval" morphologies, during which Cassini measured the interplanetary magnetic field (IMF) upstream of Saturn's bow shock over intervals of several hours. The auroras general…
Survey of Saturn auroral storms observed by the Hubble Space Telescope: Implications for storm time scales
Nichols, J. D.; Cowley, S. W. H.; Meredith, C. J.
We examine the ultraviolet images of Saturn obtained by the Hubble Space Telescope (HST) between 1997 and 2013 for the presence of auroral storm signatures, consisting of 2060 individual images over 74.4 h of exposure time. We find 12 storm intervals in these data, identified by bright high-latitude auroras spanning the dawn sector, which previous…
Transient small-scale structure in the main auroral emission at Jupiter
Bonfond, B.; Palmaerts, B.; Grodent, D. +2 more
The main auroral emission at Jupiter results from the ionosphere-magnetosphere coupling current system associated with the corotation breakdown of iogenic plasma in the current sheet. The morphology and brightness of the main auroral emission are generally suggested to be stable during time intervals of the order of an hour. Here we reveal a trans…
Effect of plasma torus density variations on the morphology and brightness of the Io footprint
Crary, F.; Payan, A. P.; Rajendar, A. +1 more
We develop a 2-D-layered model of the Io plasma torus to study the apparent "shutoff" of the Io footprint in 2007, when it disappeared beneath a region of diffuse emissions, roughly coincident with a massive eruption of Tvashtar Paterae. First, we investigate the effects of Io's location in the plasma torus and validate our model results against H…