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See detailJupiter's equatorward auroral features
Dumont, Maïté ULg; Grodent, Denis ULg; Radioti, Aikaterini ULg et al

Conference (2015, May 13)

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See detailJupiter's equatorward auroral features : Possible signature of magnetospheric injections
Dumont, Maïté ULg; Grodent, Denis ULg; Radioti, Aikaterini ULg et al

Conference (2014, September)

We investigate the characteristics of ultraviolet auroral features located equatorward of the main emission appearing in the Hubble Space Telescope (HST) images obtained in 2000-2007. Several properties ... [more ▼]

We investigate the characteristics of ultraviolet auroral features located equatorward of the main emission appearing in the Hubble Space Telescope (HST) images obtained in 2000-2007. Several properties of the auroral emissions are analyzed. The mapped radial position and System III longitude of the observed auroral features are in good agreement with those of the injections observed in the equatorial plane by Galileo. Finally, we discuss the processes causing auroral signatures of injections. This comparative study demonstrates that the structures under study are most probably related to magnetospheric injections and sheds light to the mechanism involved in the magnetosphere-ionosphere dynamics. [less ▲]

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See detailJupiter's equatorward auroral features: possible signatures of magnetospheric injections
Dumont, Maïté ULg; Grodent, Denis ULg; Radioti, Aikaterini ULg et al

in Journal of Geophysical Research. Space Physics (2014)

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 ... [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 range of local times in the same image. Several properties of these features are analyzed, such as their location, emitted power and lifetime. Additionally, we magnetically map the auroral features to the equatorial plane using the VIPAL model in order to compare their observed properties with those of magnetospheric injections detected by the Galileo spacecraft. The equatorward auroral features show up between the Io footpath and the main auroral emission, at all System III longitudes, in agreement with Galileo measurements. Moreover, we compare the magnetic flux associated with these features with estimates of the out-going flux related to the radial transport of plasma in the Jovian magnetosphere and we find that they could account for at least one third of this flux. This comparative study shows that the auroral features under study are most probably related to magnetospheric injections and thus sheds light on the processes involved in the magnetosphere-ionosphere dynamics. [less ▲]

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See detailJupiter’s magnetopause: A search for wave and reconnection signatures
Bonfond, Bertrand ULg; Kivelson, M. G.; Khurana, K. K. et al

Conference (2014, September 12)

Surface waves and magnetic reconnection are two key processes taking place at the planetary magnetopause. They allow the coupling, through energy (and particle) transfer, of the interplanetary medium and ... [more ▼]

Surface waves and magnetic reconnection are two key processes taking place at the planetary magnetopause. They allow the coupling, through energy (and particle) transfer, of the interplanetary medium and the magnetosphere. The relative importance of large scale Dungey reconnection and viscous interaction (including small-scale intermittent reconnection associated with Kelvin-Helmholtz vortices) are expected to be different at Jupiter compared to the Earth’s case. Such differences would be due to the combination of a) a weaker solar wind pressure and Alfvén velocity as the distance to the Sun increases, b) a high-β plasma sheet, originating from Io’s outgassing, which inflates the Jovian magnetosphere, c) the rapid rotation of the planet relative to its size (e.g. Desroche et al. 2012). Here we analyse the signatures of wave activity and reconnection on the magnetopause of Jupiter, based on magnetic field and energetic particle measurements from the successive spacecraft that explored the Jovian system. Up to now, 7 spacecraft equipped with a magnetometer have crossed the Jovian magnetopause: Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, Ulysses, Galileo and Cassini. We make use of several normal direction finding techniques, such as the Minimum Variance Analysis, in order to identify waves and Kelvin-Helmholtz vortices. As far as the reconnection is concerned, small scale signatures of flux-tube events (FTEs) had been identified by Walker and Russell (1985), based on a limited data-set from the Pioneers’ and Voyagers’ fly-bys. Here we will extend this search to the extensive dataset from all the missions that explored Jupiter’s system. [less ▲]

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See detailJupiter's Magnetotail
Krupp, Norbert; Kronberg, Elena; Radioti, Aikaterini ULg

in AGU Monograph (2014)

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See detailJupiter’s main auroral emission; local time and temporal variability
Grodent, Denis ULg; Radioti, Aikaterini ULg; Bonfond, Bertrand ULg et al

Conference (2008, September 23)

Jupiter's main auroral oval is associated with the ionosphere-magnetosphere coupling current system which is related to the breakdown of corotation in the middle magnetosphere. Its auroral footpath is ... [more ▼]

Jupiter's main auroral oval is associated with the ionosphere-magnetosphere coupling current system which is related to the breakdown of corotation in the middle magnetosphere. Its auroral footpath is usually represented as a smooth line closing around the pole. However, this simplistic view is misleading in many regards. We have constructed a new reference contour in the northern hemisphere (Figure 1), based on more than 1000 HST/UV images, which does not look like an oval and does not close around the pole. We use this reference contour to quantify the effects of temporal and local time variability of the magnetospheric plasma characteristics on the location of the main auroral emission. Beyond the orbit of Ganymede (15RJ), two key ingredients are expected to have a measurable influence on the instantaneous shape of the main emission contour: the azimuthal current flowing in the current sheet [1,2] and the corotation breakdown distance. The former affects the radial extent of the magnetic field lines, and the latter determines the radial location of the field aligned currents transmitting momentum from the planet to the lagging plasma. So far, models used to magnetically map the auroral main emission between the ionosphere and the equatorial plane assumed that these two parameters are constant and axisymmetric. However, in situ observations, mainly by Galileo, have revealed large local time asymmetries and temporal variations in the plasma flows and distribution. These variations have an impact on the azimuthal current and the distance at which the plasma angular velocity becomes significantly smaller than planetary rotation. We use a new magnetic field model [3], inherited from VIP4 and including a magnetic anomaly in the northern hemisphere, to simulate the effects of these asymmetries on the location of the main auroral emission, and interpret the large scattering of the corresponding HST data point. [less ▲]

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See detailJupiter's main auroral oval observed with HST-STIS
Grodent, Denis ULg; Clarke, J. T.; Kim, J. et al

in Journal of Geophysical Research. Space Physics (2003), 108(A11),

An extended series of FUV images obtained on 7 days during winter 2000-2001, with fixed pointing, yielded highly accurate tracking of emisson features as Jupiter rotated. They provided newly detailed ... [more ▼]

An extended series of FUV images obtained on 7 days during winter 2000-2001, with fixed pointing, yielded highly accurate tracking of emisson features as Jupiter rotated. They provided newly detailed measurements of the degree of corotation of auroral emissions and their variations with changing central meridian longitude. This 2-month data set provides a statistical average location of the auroral emission and leads to the definition of new "reference ovals.'' The overall auroral morphology pattern is shown to be fixed in System-III longitude and unchanged over a 5-year period. When arranged in central meridian longitude ranges, the images show a significant contraction of the northern main oval as the central meridian longitude increases from 115 to 255degrees. The main auroral oval brightness is globally very stable in comparison with its terrestrial counterpart. It is shown to vary with magnetic local time, increasing from noon to dusk and then decreasing again in the magnetic evening. Hectometric emissions observed simultaneously with Galileo and Cassini reveal interplanetary shocks propagating outward from the Sun which may be related to the contraction of the main auroral oval observed in the HST images taken on 14 December 2000. In addition, we find that a brightening and a significant contraction of the main oval observed on 13 January 2001 corresponded to a time of increased solar wind dynamic pressure. [less ▲]

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See detailJupiter’s main auroral oval: what main oval?
Grodent, Denis ULg; Gérard, Jean-Claude ULg; Radioti, Aikaterini ULg et al

Poster (2007, April 15)

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See detailJupiter’s polar auroral dynamics
Grodent, Denis ULg; Bonfond, Bertrand ULg

in AAS/Division for Planetary Sciences Meeting Abstracts (2014, November 01)

The morphology of Jupiter’s ultraviolet aurora is commonly described in terms of components located inside (poleward of) or outside (equatorward of) the main oval emission. These components may also be ... [more ▼]

The morphology of Jupiter’s ultraviolet aurora is commonly described in terms of components located inside (poleward of) or outside (equatorward of) the main oval emission. These components may also be discriminated by their temporal behaviour, where the narrowest parts of the main “oval” remain relatively stable over time periods of several hours, and the satellite footprints show large variability with timescales of minutes. Inside the main emission the so-called polar aurora, presumably corresponding to the polar cap mixing open and closed magnetic field lines, is characterized by rapid motions taking the form of swirls, giving rise to the “swirl region” and by intermittent brightenings in the “active region”. Coarse analysis of these motions suggests that they are too fast to respond to an equatorial magnetospheric forcing. Instead, they appear to be related to processes taking place in or above the ionosphere where distances travelled by plasma waves match those of the subtended auroral emission. Here, we present a preliminary improved analysis of the auroral motion in the polar region based on the application of an iterative “Advection Corrected Correlation Image Velocimetry” (ACCIV) method (Asay-Davis et al., 2009). This method allows one to build velocity fields quantifying local and overall auroral motions which may then be used to constrain their origin. [less ▲]

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See detailJupiter's polar auroral emissions
Grodent, Denis ULg; Clarke, J. T.; Waite, J. H. et al

in Journal of Geophysical Research. Space Physics (2003), 108(A10),

[1] This paper reports a study of Jupiter's polar auroral emissions observed in an extended series of FUV images. They were obtained on seven days, during winter 2000-2001, with the STIS camera on board ... [more ▼]

[1] This paper reports a study of Jupiter's polar auroral emissions observed in an extended series of FUV images. They were obtained on seven days, during winter 2000-2001, with the STIS camera on board the Hubble Space Telescope. The fixed pointing yielded highly accurate and consistent tracking of emisson features as Jupiter rotated, allowing the analysis of the auroral morphology and brightness on timescales ranging from seconds to days. In the Northern Hemisphere, the polar emissions, located poleward of the main oval, usually represent about 30% of the total auroral FUV emitted power. They show emission bursts lasting similar to100 s, while the main oval remains stable. The polar region may be divided into three regions apparently fixed in magnetic local time: the dawnside dark region, the poleward swirl region, and the duskside active region in which flares and arc-like features are observed. Each of these UV emission regions can be identified with its infrared counterpart and probably relates to a different sector of the Dungey cycle or Vasyliunas cycle plasma flows. [less ▲]

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See detailJupiter’s polar auroral emissions-signatures of magnetic reconnection
Radioti, Aikaterini ULg; Gérard, Jean-Claude ULg; Grodent, Denis ULg et al

Conference (2007, August 23)

The polar auroral emissions at Jupiter can be divided into three regions fixed in mag- netic local time: the dawnside dark region, the poleward swirl region and the duskside active region in which flares ... [more ▼]

The polar auroral emissions at Jupiter can be divided into three regions fixed in mag- netic local time: the dawnside dark region, the poleward swirl region and the duskside active region in which flares and arc-like features are observed. Previous studies re- lated the polar emissions to the solar wind driven Dungey cycle and Vasyliunas flow cycle. Based on HST STIS and ACS images we study extensively the time variations of the morphology and brightness of various polar auroral features as well as their duration and reoccurrence. We magnetically map their location in the equatorial plane and we compare their spatial size and time scales with the reconnection events taking place in the Jovian magnetotail. We discuss the possibility that some polar auroral features are signatures of magnetic reconnection. [less ▲]

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See detailJupiter's Polar Cap Aurora
Grodent, Denis ULg; Bonfond, Bertrand ULg

Scientific conference (2014, November 18)

The morphology of Jupiter’s ultraviolet aurora is commonly described in terms of components located inside (poleward of) or outside (equatorward of) the main oval emission. These components may also be ... [more ▼]

The morphology of Jupiter’s ultraviolet aurora is commonly described in terms of components located inside (poleward of) or outside (equatorward of) the main oval emission. These components may also be discriminated by their temporal behaviour, where the narrowest parts of the main “oval” remain relatively stable over time periods of several hours, and the satellite footprints show large variability with timescales of minutes. Inside the main emission the so-called polar aurora, presumably corresponding to the polar cap mixing open and closed magnetic field lines, is characterized by rapid motions taking the form of swirls, giving rise to the “swirl region” and by intermittent brightenings in the “active region”. Coarse analysis of these motions suggests that they are too fast to respond to an equatorial magnetospheric forcing. Instead, they appear to be related to processes taking place in or above the ionosphere where distances travelled by plasma waves match those of the subtended auroral emission. Here, we present a preliminary improved analysis of the auroral motion in the polar region based on the application of an iterative “Advection Corrected Correlation Image Velocimetry” (ACCIV) method (Asay-Davis et al., 2009). This method allows one to build velocity fields quantifying local and overall auroral motions which may then be used to constrain their origin. [less ▲]

Detailed reference viewed: 34 (2 ULg)
See detailJupiter's Thermospheric General Circulation Model (JTGCM): Equatorial thermal structure in comparison with Galileo probe measurements
Majeed, T.; Bougher, S. W.; Waite, J. H. et al

Poster (2001, June 25)

Detailed reference viewed: 2 (0 ULg)
See detailJupiter's ultraviolet polar auroral emissions
Coumans, Valérie ULg; Bonfond, Bertrand ULg; Grodent, Denis ULg et al

Conference (2009, September)

Detailed reference viewed: 16 (6 ULg)
See detailJupiter's ultraviolet polar emission: a statistical study
Coumans, Valérie ULg; Bonfond, Bertrand ULg; Grodent, Denis ULg et al

Conference (2010, September)

Detailed reference viewed: 11 (5 ULg)
See detailJurés de prix littéraires. Liens et figurations
Dozo, Björn-Olav ULg

Conference given outside the academic context (2013)

Detailed reference viewed: 19 (1 ULg)
Peer Reviewed
See detailLa juridiction de l’Ordre de Cîteaux sur les communautés de la branche féminine aux Pays-Bas et dans la principauté de Liège : 15e-18e s.
Henneau, Marie-Elisabeth ULg

in Henneau, Marie-Elisabeth; Barrière, Bernadette; Bonis, Armelle (Eds.) et al Cîteaux et les femmes (2001)

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See detailJuridiction ordinaire et juridiction administrative en droit belge
Pâques, Michel ULg; Donnay, Luc ULg

in Chroniques de Droit Public = Publiekrechtelijke Kronieken (2007)

Detailed reference viewed: 48 (15 ULg)
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See detailJuridiction ordinaire et juridiction administrative en droit belge
Pâques, Michel ULg; Donnay, Luc ULg

in Ben Salah, Hafedh; Ridha Jenayah, Mohamed (Eds.) La justice administrative dans les pays du Maghreb, la réception du modèle européen (2008)

Detailed reference viewed: 532 (18 ULg)