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See detailModel of the Jovian magnetic field topology constrained by the Io auroral emissions
Hess, Sébastien; Bonfond, Bertrand ULg; Grodent, Denis ULg et al

Poster (2011, October)

The determination of the internal magnetic field of Jupiter has been the object of many studies and publications. These models have been computed from the Pioneer, Voyager, and Ulysses measurements. Some ... [more ▼]

The determination of the internal magnetic field of Jupiter has been the object of many studies and publications. These models have been computed from the Pioneer, Voyager, and Ulysses measurements. Some models also use the position of the Io footprints as a constraint: the magnetic field lines mapping to the footprints must have their origins along Io’s orbit. The use of this latter constraint to determine the internal magnetic field models greatly improved the modeling of the auroral emissions, in particular the radio ones, which strongly depends on the magnetic field geometry. This constraint is, however, not sufficient for allowing a completely accurate modeling. The fact that the footprint field line should map to a longitude close to Io’s was not used, so that the azimuthal component of the magnetic field could not be precisely constrained. Moreover, a recent study showed the presence of a magnetic anomaly in the northern hemisphere, which has never been included in any spherical harmonic decomposition of the internal magnetic field. We compute a decomposition of the Jovian internal magnetic field into spherical harmonics, which allows for a more accurate mapping of the magnetic field lines crossing Io, Europa, and Ganymede orbits to the satellite footprints observed in UV. This model, named VIPAL, is mostly constrained by the Io footprint positions, including the longitudinal constraint, and normalized by the Voyager and Pioneer magnetic field measurements. We show that the surface magnetic fields predicted by our model are more consistent with the observed frequencies of the Jovian radio emissions than those predicted by previous models. [less ▲]

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See detailBi-directional electron distributions as tracers for the open-closed field line boundary in Saturn’s magnetosphere
Krupp, Norbert; Radioti, Aikaterini ULg; Roussos, Elias et al

Conference (2011, October)

In this presentation we use bi-directional energetic electron distributions from the MIMI-LEMMS instrument onboard Cassini, auroral observations from the Hubble Space Telescope (HST) and data from the ... [more ▼]

In this presentation we use bi-directional energetic electron distributions from the MIMI-LEMMS instrument onboard Cassini, auroral observations from the Hubble Space Telescope (HST) and data from the UVIS instrument onboard Cassini to characterize the open-closed field line boundary in Saturn’s magnetosphere. The high-latitude open-closed field line boundary at Saturn is thought to be related to the main auroral ring of emission of the planet varying in location, intensity and latitudinal extent as well as in its homogeneity. This study extends the work on the plasmapause/open-closed field line boundary published by [1] by covering a larger data set at different local times and comparing the electron distributions with auroral observations. Based on energetic electron data we characterize the open-closed field line boundary in terms of temporal, local time variations and other parameters and we correlate the Cassini in-situ measurements to the observations of the main auroral ring at Saturn. [less ▲]

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See detailDetection of Auroral Emissions from Callisto’s Magnetic Footprint at Jupiter
Clarke, J. T.; Wannawichian, S.; Hernandez, N. et al

Poster (2011, October)

HST observations of Jupiter’s aurora in a large campaign reveal several cases where the main oval emission appeared at unusually low latitudes, making it possible to search for the first time for auroral ... [more ▼]

HST observations of Jupiter’s aurora in a large campaign reveal several cases where the main oval emission appeared at unusually low latitudes, making it possible to search for the first time for auroral emissions from the magnetic footprint of Callisto without the overlapping bright emissions from the main oval. Several cases have been found where point-source emissions have now been detected from locations consistent with Callisto’s magnetic footprint on Jupiter at a brightness of ten’s of kilo- Rayleighs. These observations confirm that there is an electrodynamic interaction between Callisto and Jupiter’s magnetospheric environment that is similar to those at Io, Europa, and Ganymede, which all have auroral footprints. The properties of the emissions and a comparison with other observations and theoretical expectations will be presented in this paper. [less ▲]

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See detailUV and visible planetary auroral emissions: Jupiter and Saturn
Grodent, Denis ULg

Conference (2011, October)

In the giant planets upper atmosphere, collisions of auroral electrons with atmospheric H atoms and H2 molecules, following acceleration along magnetic field lines, give rise to excitation of these ... [more ▼]

In the giant planets upper atmosphere, collisions of auroral electrons with atmospheric H atoms and H2 molecules, following acceleration along magnetic field lines, give rise to excitation of these primary neutrals. Excited H and H2 almost immediately loose part of (~15%) their excess energy through radiative decay processes implying emission of FUV, EUV, NUV and visible light. An observer located near Earth orbit will only see the sunlit portion of the giant planets for which the reflected sunlight outshines a large portion of the hydrogen auroral emissions. Fortunately, the solar spectrum drops by several orders of magnitude in the FUV-EUV bandpass and is further attenuated by low altitude hydrocarbon haze produced in the polar regions. This makes it possible to observe Jupiter and Saturn EUV and FUV auroras from Earth orbit with, for example, the UV cameras onboard the Hubble Space Telescope. These cameras provided numerous fantastic views of Jupiter and Saturn's polar auroral emissions. By contrast, the dimmer NUV and visible auroral emissions cannot compete with the solar light and can only be observed on the night side hemisphere of Jupiter and Saturn; out of visibility from Earth orbit. This region is accessible to in situ spacecraft, like Galileo, Cassini or NewHorizons, which have to share their precious observing time among several different scientific topics. As a result, images of the NUV and visible auroral emissions are rare, in comparison with the huge HST database. Nevertheless, the fact that they are only captured in the night side implies that the origin of the energetic particles that gave rise to them is principally found in the immense magnetospheric tail; a vast region where energetic electromagnetic processes and plasma motions are still poorly documented. This makes these emissions invaluable in terms of scientific return. [less ▲]

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See detailJUDE: A Far-UV Imager for JUICE
Grodent, Denis ULg; Bunce, Emma; Bannister, Nigel et al

Poster (2011, August 31)

Detailed reference viewed: 40 (5 ULg)
See detailUV-IR comparison: Jupiter aurora
Gérard, Jean-Claude ULg; Grodent, Denis ULg

Conference (2011, August)

Detailed reference viewed: 16 (1 ULg)
See detailThe Ultraviolet Spectrograph (UVS) on Juno
Gladstone, G. R.; Persyn, S.; Eterno, J. et al

Poster (2011, July 11)

Detailed reference viewed: 32 (5 ULg)
See detailCassini UVIS Observations of Varying Auroral Emissions on Saturn's Night Side
Pryor, W.; Esposito, L.; Jouchoux, A. et al

Poster (2011, July 11)

Detailed reference viewed: 12 (3 ULg)
See detailAuroral signatures of injections in the magnetosphere of Saturn
Radioti, Aikaterini ULg; Roussos, E.; Grodent, Denis ULg et al

Poster (2011, July 11)

Detailed reference viewed: 22 (12 ULg)
See detailMapping Jupiter's auroral features to magnetospheric sources: Comparing results from three different models for Jupiter's ionospheric magnetic field
Vogt, M. F.; Kivelson, M. G.; Khurana, K. K. et al

Conference (2011, July 11)

Detailed reference viewed: 11 (1 ULg)
See detailInside the Jupiter Main Auroral Emissions: Flares, Spots, Arc...and Satellite Footprints?
Bonfond, Bertrand ULg; Vogt, M. F.; Yoneda, M. et al

Conference (2011, July 11)

Detailed reference viewed: 22 (11 ULg)
See detailThe multiple spots of the Ganymede footprint
Bonfond, Bertrand ULg; Hess, S.; Grodent, Denis ULg et al

Poster (2011, July 11)

Detailed reference viewed: 16 (7 ULg)
See detailModel of the Jovian magnetic field topology constrained by the Io auroral emissions
Hess, S.; Bonfond, Bertrand ULg; Grodent, Denis ULg et al

Poster (2011, July 11)

Detailed reference viewed: 3 (1 ULg)
See detailAuroral emissions of Europa
Grodent, Denis ULg

Conference (2011, June 01)

Detailed reference viewed: 9 (1 ULg)
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See detailImproved mapping of Jupiter’s auroral features to magnetospheric sources
Vogt, Marissa. F.; Kivelson, Margaret. G.; Khurana, Krishan. K. et al

in Journal of Geophysical Research. Space Physics (2011), 116

The magnetospheric mapping of Jupiter's polar auroral emissions is highly uncertain because global Jovian field models are known to be inaccurate beyond ∼30 RJ. Furthermore, the boundary between open and ... [more ▼]

The magnetospheric mapping of Jupiter's polar auroral emissions is highly uncertain because global Jovian field models are known to be inaccurate beyond ∼30 RJ. Furthermore, the boundary between open and closed flux in the ionosphere is not well defined because, unlike the Earth, the main auroral oval emissions at Jupiter are likely associated with the breakdown of plasma corotation and not the open/closed flux boundary in the polar cap. We have mapped contours of constant radial distance from the magnetic equator to the ionosphere in order to understand how auroral features relate to magnetospheric sources. Instead of following model field lines, we map equatorial regions to the ionosphere by requiring that the magnetic flux in some specified region at the equator equals the magnetic flux in the area to which it maps in the ionosphere. Equating the fluxes in this way allows us to link a given position in the magnetosphere to a position in the ionosphere. We find that the polar auroral active region maps to field lines beyond the dayside magnetopause that can be interpreted as Jupiter's polar cusp; the swirl region maps to lobe field lines on the night side and can be interpreted as Jupiter's polar cap; the dark region spans both open and closed field lines and must be explained by multiple processes. Additionally, we conclude that the flux through most of the area inside the main oval matches the magnetic flux contained in the magnetotail lobes and is probably open to the solar wind. [less ▲]

Detailed reference viewed: 41 (13 ULg)
See detailJupiter's Aurora as Imaged by the NASA IRTF and Comparison with Hubble Space Telescope Observations in the UV
Lystrup, M.; Radioti, Aikaterini ULg; Bonfond, Bertrand ULg et al

Conference (2011, March)

We investigate Jupiter's infrared aurora using observations from the NASA Infrared Telescope Facility from 1995-2000 as compared with observations in the UV from the Hubble Space Telescope.

Detailed reference viewed: 24 (2 ULg)
See detailLes aurores de Jupiter et Saturne : la crise énergétique des planètes géantes
Grodent, Denis ULg

Conference given outside the academic context (2011)

Detailed reference viewed: 4 (0 ULg)