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Origin of Saturn's aurora: Simultaneous observations by Cassini and the Hubble Space Telescope
Coates, A. J.; Dougherty, M. K.; Nichols, J. D. +9 more
Outer planet auroras have been imaged for more than a decade, yet understanding their physical origin requires simultaneous remote and in situ observations. The first such measurements at Saturn were obtained in January 2007, when the Hubble Space Telescope imaged the ultraviolet aurora, while the Cassini spacecraft crossed field lines connected t…
Auroral evidence of a localized magnetic anomaly in Jupiter's northern hemisphere
Gustin, Jacques; Clarke, John T.; Connerney, John E. P. +5 more
We analyze more than 1000 HST/Advanced Camera for Survey images of the ultraviolet auroral emissions appearing in the northern hemisphere of Jupiter. The auroral footprints of Io, Europa, and Ganymede form individual footpaths, which are fitted with three reference contours. The satellite footprints provide a convenient mapping between the norther…
Oscillation of Saturn's southern auroral oval
Nichols, J. D.; Clarke, J. T.; Cowley, S. W. H. +5 more
Near-planetary-period oscillations in the Cassini plasma and magnetic field data have been observed throughout Saturn's magnetosphere despite the fact that Saturn's internal magnetic field is apparently highly axisymmetric. In addition, the period of the Saturn kilometric radiation has been shown to vary over time. In this paper we present results…
Spectral morphology of the X-ray emission from Jupiter's aurorae
Branduardi-Raymont, G.; Galand, M.; Waite, J. H. +5 more
Simultaneous Chandra X-ray and Hubble Space Telescope FUV observations of Jupiter's aurorae carried out in February 2003 have been re-examined to investigate the spatial morphology of the X-ray events in different energy bands. The data clearly show that in the Northern auroral region (in the main auroral oval and the polar cap) events with energy…
Discontinuity in Jupiter's main auroral oval
Krupp, N.; Woch, J.; Bonfond, B. +3 more
On the basis of a series of FUV Hubble Space Telescope images obtained between 1997 and 2007 it is shown that there is a segment of the main auroral oval where the emission drops significantly from a few hundreds to a few tens of kiloRayleigh, forming a discontinuity in the oval. It is shown that the discontinuity is present in both hemispheres an…
Jupiter's changing auroral location
Grodent, Denis; GéRard, Jean-Claude; Saglam, Adem +2 more
We examine the case of significant latitudinal shifts of the Jovian northern auroral emissions appearing in a data set spanning nine years of observations with the Hubble Space Telescope in the far ultraviolet. The extended data set makes it possible to compare the location of the main auroral emission with similar viewing geometries and satellite…
Interaction evidence between Enceladus' atmosphere and Saturn's magnetosphere
Clarke, J. T.; Wannawichian, S.; Pontius, D. H.
Saturn's ultraviolet (UV) auroras are highly variable, with much of the activity believed to be controlled by conditions in the solar wind. Like Jupiter, Saturn is also expected to have an electrodynamic interaction between the planet's ionosphere and its satellites' atmospheres, a process that is responsible for the moon's auroral footprint compo…