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See detailAuroral signatures of multiple magnetopause reconnection at Saturn
Radioti, Aikaterini ULg; Grodent, Denis ULg; Gérard, Jean-Claude ULg et al

in Geophysical Research Letters (2013)

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See detailAuroral signatures of reconnection at Saturn and comparison with Earth
Radioti, Aikaterini ULg

Conference (2014, July)

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See detailAn auroral source of hot oxygen in the geocorona
Shematovich, V. I.; Bisikalo, D. V.; Gérard, Jean-Claude ULg

in Geophysical Research Letters (2005), 32

The high-energy proton-hydrogen (H[SUP]+[/SUP]/H) beam associated with proton auroral precipitation transfers momentum in elastic and inelastic collisions with ambient thermal atomic oxygen in the high ... [more ▼]

The high-energy proton-hydrogen (H[SUP]+[/SUP]/H) beam associated with proton auroral precipitation transfers momentum in elastic and inelastic collisions with ambient thermal atomic oxygen in the high latitude thermosphere. This process provides a localized novel source of hot oxygen atoms in addition to exothermic photochemistry, charge exchange and momentum transfer from O[SUP]+[/SUP] ion precipitation and charge exchange with accelerated ionospheric O[SUP]+[/SUP] ions. We suggest that this source contributes to the population of the hot oxygen geocorona and to the flux of escaping oxygen atoms. For an incident proton energy flux of 1 mW m[SUP]-2[/SUP] and a mean energy E[SUB]mean[/SUB] ~ 5 keV, we calculate a density of hot oxygen atoms with energy above 1 eV of 2.0 × 10[SUP]3[/SUP] cm[SUP]-3[/SUP] and a mean kinetic energy of about 3.5 eV at 700 km. The total upward flux of hot oxygen atoms with energies higher 1 eV is estimated as 3.5 × 10[SUP]8[/SUP] cm[SUP]-2[/SUP] s[SUP]-1[/SUP]. [less ▲]

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See detailAuroral spirals at Saturn
Radioti, Aikaterini ULg; Grodent, Denis ULg; Gérard, Jean-Claude ULg et al

Conference (2015)

We report Cassini/UVIS observations of auroral vortices at Saturn propagating from midnight to noon via dawn. The emission in the dawn auroral sector is observed to consist of several detached features ... [more ▼]

We report Cassini/UVIS observations of auroral vortices at Saturn propagating from midnight to noon via dawn. The emission in the dawn auroral sector is observed to consist of several detached features that swirl with time. They have a diameter of 6000 km in the ionosphere, which would correspond to plasma vortices in the magnetosphere of 12 to 15 Rs. ENA enhancements are observed simultaneously. However, they do not show any clear vortices. We estimate the velocity of the UV auroral feature to decrease from 85% of rigid corotation (28o/h) in the most equatorward part of the aurora to 68% of rigid corotation (22o/h) in the poleward part and we demonstrate that such velocity gradient could result in swirling auroral features. Particle velocities derived from magnetospheric data in previous studies, confirm large variations of the corotation fraction as a function of radial distance. We suggest that the auroral vortices could be the ionospheric footprints of hot dynamic populations containing strong velocity gradients. Alternatively, we consider another scenario that could generate auroral vortices based on field line deformation from the magnetosphere to the ionosphere, like it is proposed for the Earth. In that case the auroral spiral is the result of some processes that occurred in the transition region between the centers of vortices where strong shear flows existed. Finally, a third possibility is considered, according to which the auroral vortices reported here are the direct optical signatures of the plasma vortical flows in the magnetopause related to Kelvin-Helmholtz instabilities. However, this might be less possible due to the very different spatial scales of the auroral features (12-15 Rs) and the observed plasma vortices in the magnetopause (1 Rs). [less ▲]

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See detailAuroral streamers and magnetic flux closure
Hubert, Benoît ULg; Kauristie, K.; Amm, O. et al

in Geophysical Research Letters (2007), 34(15),

On 7 December 2000 at 2200 UT an auroral streamer was observed to develop above Scandinavia with the IMAGE-FUV global imagers. The ionospheric equivalent current deduced from the MIRACLE-IMAGE ... [more ▼]

On 7 December 2000 at 2200 UT an auroral streamer was observed to develop above Scandinavia with the IMAGE-FUV global imagers. The ionospheric equivalent current deduced from the MIRACLE-IMAGE Scandinavian ground-based network of magnetometers is typical of a substorm-time streamer. Observations of the proton aurora using the SI12 imager onboard the IMAGE satellite are combined with measurements of the ionospheric convection obtained by the SuperDARN radar network to compute the dayside merging and nightside flux closure rates. On the basis of this and other similar events, it is found that auroral streamers appear during the period of most intense flux closure in the magnetotail, most often shortly after substorm onset. The ionospheric convection velocity, as measured by SuperDARN, appears to be reduced in the vicinity of the streamer, suggesting de-coupling of magnetospheric and ionospheric plasma flows in the region of enhanced ionospheric conductance. [less ▲]

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See detailAuroral ultraviolet emissions
Gérard, Jean-Claude ULg

in Physics and chemistry of atmospheres (1975)

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See detailL'Aurore des fanzineux
Capart, Philippe; Dejasse, Erwin ULg; Paques, Frédéric ULg

in Art&Fact (2012), 31

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See detailLes aurores boréales sur les planètes géantes. La « crise énergétique des planètes géantes »
Grodent, Denis ULg

Conference given outside the academic context (2011)

Les planètes géantes comme Jupiter et Saturne ont en commun une masse importante, l’absence de surface, une atmosphère dominée par l’hydrogène moléculaire et l’hélium ainsi qu'une grande variété ... [more ▼]

Les planètes géantes comme Jupiter et Saturne ont en commun une masse importante, l’absence de surface, une atmosphère dominée par l’hydrogène moléculaire et l’hélium ainsi qu'une grande variété d’hydrocarbures. Leur rotation rapide est à l'origine d'un champ magnétique particulièrement intense qui permet de transférer de grandes quantités d'énergie de la planète vers les particules ionisées qui les entourent. Cet échange s'effectue via des courants électriques extrêmement intenses qui, en interagissant avec l'atmosphère, provoquent des émissions aurorales. Nous décrirons des processus de précipitation d’électrons énergétiques dans l'atmosphère de Jupiter et nous nous intéresserons aux spectaculaires aurores polaires qui leur sont associées. Ces dernières seront illustrées par des images et animations obtenues dans l’ultraviolet à l’aide du Télescope Spatial Hubble. Nous montrerons comment les précipitations aurorales contrôlent dans une large mesure la température de la haute atmosphère de ces planètes et permettent de résoudre la « crise énergétique » des planètes géantes. [less ▲]

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See detailLes aurores dans le système solaire
Grodent, Denis ULg

Conference given outside the academic context (2002)

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See detailLes aurores de Jupiter et Saturne : la crise énergétique des planètes géantes
Grodent, Denis ULg

Conference given outside the academic context (2011)

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See detailAurores sur les planètes géantes
Bonfond, Bertrand ULg

Scientific conference (2011, December 08)

Depuis les premières détections d'émissions aurorales par les sondes Voyager à la fin des années 70, nos connaissances des aurores de Jupiter et de Saturne ont considérablement progressé. Je présenterai ... [more ▼]

Depuis les premières détections d'émissions aurorales par les sondes Voyager à la fin des années 70, nos connaissances des aurores de Jupiter et de Saturne ont considérablement progressé. Je présenterai ici quelques uns des derniers résultats obtenus à l'aide du télescope spatial Hubble et de la sonde Cassini en orbite autour de Saturne. Ces images acquises dans le domaine ultraviolet révèlent une complexité que l'on commence seulement à appréhender. Assemblées en séquences, elles dévoilent une dynamique surprenante. Flashs, pulsations, expansions, contractions, apparitions, disparitions, fusions, séparations et mouvements relatifs de structures étendues sur des dizaines de milliers de kilomètres ou localisés sur quelques centaines de kilomètres : la diversité des comportements que nous observons est le témoignage de la richesse des processus en œuvre dans les magnétosphères de Jupiter et Saturne. Lunes exotiques, volcans et geysers colossaux, champs magnétiques gigantesques et rotations planétaires rapides sont les ingrédients de ce surprenant laboratoire de physique des plasmas. [less ▲]

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See detailAurores, les lumières atmosphériques
Nazé, Yaël ULg

Article for general public (2009)

Detailed reference viewed: 14 (1 ULg)
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See detailAuschwitz – ein Symbol?
Pontzen, Alexandra ULg

in Literaturkritik.de (2009)

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See detailAuscultation of cardiac murmurs in horses
Amory, Hélène ULg

in Proceedings of 12th Moscow International Veterinary Congress (2004)

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See detailAusdauer versus kraft-ausdauertraining bei freizeitsadsportlern
Weiler, B.; Urhausen, A.; Dahm, C. et al

in Abstractband "Deutsche Zeitschrift für sportmedizin" (1999, September)

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See detailThe Australian Apology in Fiction: Gail Jones’s Sorry
Belleflamme, Valérie-Anne ULg

Scientific conference (2014, November 28)

Detailed reference viewed: 29 (11 ULg)
See detailThe Australian Apology in Fiction: Gail Jones's Sorry
Belleflamme, Valérie-Anne ULg

Article for general public (2014)

Detailed reference viewed: 1 (0 ULg)