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Peer Reviewed
See detailA journey in the analytical chemistry of dioxins
Focant, Jean-François ULiege

in LIBRO DE RESÚMENES (2011, June)

Detailed reference viewed: 11 (2 ULiège)
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See detailA Journey Through Julia: A dynamic and fast language
Cuvelier, Thibaut ULiege

Speech/Talk (2017)

Usually, dynamic programming languages (like Python, R, or MATLAB) are quite slow when executed, which causes performance problems in many applications. Julia is a blossoming language, both dynamic and ... [more ▼]

Usually, dynamic programming languages (like Python, R, or MATLAB) are quite slow when executed, which causes performance problems in many applications. Julia is a blossoming language, both dynamic and fast, fully open source, with a syntax that is very similar to that of MATLAB. This talk presents briefly Julia and its ecosystem. [less ▲]

Detailed reference viewed: 22 (2 ULiège)
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See detailA Journey Through Julia: A dynamic and fast language
Cuvelier, Thibaut ULiege

Speech/Talk (2016)

Usually, dynamic programming languages (like Python, R, or MATLAB) are quite slow when executed, which causes performance problems in many applications. Julia is a blossoming language, both dynamic and ... [more ▼]

Usually, dynamic programming languages (like Python, R, or MATLAB) are quite slow when executed, which causes performance problems in many applications. Julia is a blossoming language, both dynamic and fast, fully open source, with a syntax that is very similar to that of MATLAB. This talk presents briefly Julia and its ecosystem. [less ▲]

Detailed reference viewed: 209 (37 ULiège)
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See detaila journey through stable isotopes applications in trophic ecology
Lepoint, Gilles ULiege

Learning material (2017)

Detailed reference viewed: 16 (2 ULiège)
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Peer Reviewed
See detailJours fastes et néfastes dans le calendrier public romain, à la fin de la République et au début du Principat. Une dichotomie hémérologique éloignée de son usage moderne.
Berthelet, Yann ULiege

in Marti, Lionel (Ed.) Les hémérologies, une approche comparée : Mésopotamie, Rome, Chine, Japon (titre provisoire). (in press)

Detailed reference viewed: 28 (9 ULiège)
See detailJours fastes et néfastes dans les calendriers romains
Berthelet, Yann ULiege

Scientific conference (2016, January 12)

Detailed reference viewed: 45 (6 ULiège)
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See detailJovian aurora from Juno perijove passes: comparison of ultraviolet and infrared images
Gérard, Jean-Claude ULiege; Bonfond, Bertrand ULiege; Adriani, A. et al

Conference (2017, September 01)

The electromagnetic radiation emitted by the Jovian aurora extends from the X-Rays presumably caused by heavy ion precipitation and electron bremsstrahlung to thermal infrared radiation resulting from ... [more ▼]

The electromagnetic radiation emitted by the Jovian aurora extends from the X-Rays presumably caused by heavy ion precipitation and electron bremsstrahlung to thermal infrared radiation resulting from enhanced heating by high-energy charged particles. Many observations have been made since the 1990s with the Hubble Space Telescope, which was able to image the H2 Lyman and Werner bands that are directly excited by collisions of auroral electrons with H2. Ground-based telescopes obtained spectra and images of the thermal H3+ emission produced by charge transfer between H2+ and H+ ions and neutral H2 molecules in the lower thermosphere. However, so far the geometry of the observations limited the coverage from Earth orbit and only one case of simultaneous UV and infrared emissions has been described in the literature. The Juno mission provides the unique advantage to observe both Jovian hemispheres simultaneously in the two wavelength regions simultaneously and offers a more global coverage with unprecedented spatial resolution. This was the case. [less ▲]

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See detailThe Jovian Aurora: Implications of Multiwavelength Auroral Spectra for Auroral Particle Identity and Auroral Microphysics
Waite, J. H.; Gladstone, G. R.; Bolton, S. J. et al

in Bulletin of the American Astronomical Society (1998, September 01)

Remote sensing of Jupiter's aurora from x-ray to radio wavelengths has revealed much about the nature of the jovian aurora and about the impact of ionosphere-magnetosphere coupling on Jupiter's upper ... [more ▼]

Remote sensing of Jupiter's aurora from x-ray to radio wavelengths has revealed much about the nature of the jovian aurora and about the impact of ionosphere-magnetosphere coupling on Jupiter's upper atmosphere. Both energetic heavy ions and electrons energized in the outer magnetosphere contribute to the auroral excitation, as indicated by the combination of x-ray and ultraviolet observations. Imaging with the HST in the ultraviolet and with the IRTF at infrared wavelengths reveals several distinct regions of interaction: 1) a dusk sector where turbulent auroral patterns extend well into the polar cap; 2) a morning sector generally characterized by a single spatially confined auroral arc originating in the outer magnetosphere of Jupiter; 3) diffuse emissions associated with the Io plasma torus; and 4) a distinct region associated with the Io Flux Tube footprint. Ultraviolet spectroscopy has provided important information about the thermal structure of the upper atmosphere and altitude distribution of the auroral particle energy deposition, while Lyman alpha line profiles offer clues to the nature of thermospheric dynamical effects. Galileo observations at visible wavelengths on the nightside have provided a new view of the jovian aurora with unprecedented spatial information. Infrared observations have added much to the understanding of thermal structure and morphology and may hold the key to understanding the role of Joule heating. Radio observations imply that energetic particle precipitation extends to low latitudes, a result that has been corroborated at x-ray wavelengths. Multispectral observations of jovian auroral emissions will be discussed within a theoretical/modeling framework that serves to provide some insight into magnetosphere-ionosphere coupling and its effect on the upper atmosphere. Particular emphasis will be placed on the use of auroral spectra to identify incident energetic particles and their energy spectra as a means of elucidating the microphysics of auroral processes. [less ▲]

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See detailJovian Auroral Lyalpha Self-Reversals: A Window on Jupiter's Auroral Electrojet?
Gladstone, G. R.; Waite, J H, Jr; Gérard, Jean-Claude ULiege

in Bulletin of the American Astronomical Society (1998, September 01)

High-resolution GHRS profiles of Lyalpha lines emitted from Jupiter's auroral regions were presented by Prang{e} et al. (Astrophys. J., 484, L169--L173, 1997). Their data show asymmetric self-reversed ... [more ▼]

High-resolution GHRS profiles of Lyalpha lines emitted from Jupiter's auroral regions were presented by Prang{e} et al. (Astrophys. J., 484, L169--L173, 1997). Their data show asymmetric self-reversed line profiles, with the blue or red peak brighter depending on the target location in Jupiter's northern auroral region. The measured asymmetries are equivalent to Doppler velocities towards and away from the observer of several km/s. As suggested by Sommeria et al. (Icarus, 119, 2--24, 1995), electrojet velocities of ~ 10--20 km/s may be present at Jupiter. Here we investigate the possibility that the observed wavelength shifts of the auroral Lyalpha line are a result of multiple scattering by H atoms carried along in Jupiter's auroral electrojet. If this explanation is found to be viable, then HST/STIS mapping of the velocity shifts in the Lyalpha line may represent (as with ground-based high-resolution observations of jovian auroral H_3(+) emission lines) a means for determining the dynamics of Jupiter's upper atmosphere and ionosphere. [less ▲]

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Peer Reviewed
See detailJovian auroral spectroscopy with FUSE: analysis of self-absorption and implications for electron precipitation
Gustin, Jacques ULiege; Feldman, Paul D.; Gérard, Jean-Claude ULiege et al

in Icarus: International Journal of Solar System Studies (2004), 171(2), 336-355

High-resolution (similar to 0.22 Angstrom) spectra of the north jovian aurora were obtained in the 905-1180 Angstrom window with the Far Ultraviolet Spectroscopic Explorer (FUSE) on October 28, 2000. The ... [more ▼]

High-resolution (similar to 0.22 Angstrom) spectra of the north jovian aurora were obtained in the 905-1180 Angstrom window with the Far Ultraviolet Spectroscopic Explorer (FUSE) on October 28, 2000. The FUSE instrument resolves the rotational structure of the H-2 spectra and the spectral range allows the study of self-absorption. Below 1100 Angstrom, transitions connecting to the upsilon" less than or equal to 2 levels of the H-2 ground state are partially or totally absorbed by the overlying H2 molecules. The FUSE spectra provide information on the overlying H2 column and on the vibrational distribution of H-2. Transitions from high-energy H-2 Rydberg states and treatment of self-absorption are considered in our synthetic spectral generator. We show comparisons between synthetic and observed spectra in the 920-970, 1030-1080, and 1090-1180 Angstrom spectral windows. In a first approach (single-layer model), the synthetic spectra are venerated in a thin emitting layer and the emerging photons are absorbed by a layer located above the source. It is found that the parameters of the single-layer model best fitting the three spectral windows are 850, 800, and 800 K respectively for the H-2 gas temperature and 1.3 x 10(18), 1.5 x 10(20), and 1.3 x 10(20) cm(-2) for the H-2 self-absorbing vertical column respectively. Comparison between the H-2 column and a 1-D atmospheric model indicates that the short-wavelength FUV auroral emission originates from just above the homopause. This is confirmed by the high H-2 rovibrational temperatures, close to those deduced from spectral analyses of H-3(+) auroral emission. In a second approach, the synthetic spectral generator is coupled with a vertically distributed 3 energy degradation model, where the only input is the energy distribution of incoming electrons (multi-layer model). The model that best fits globally the three FUSE spectra is a sum of Maxwellian functions, with characteristic energies ranging from 1 to 100 keV, giving rise to an emission peak located at 5 mubar, that is similar to 100 km below the methane homopause. This multi-layer model is also applied to a re-analysis of the Hopkins Ultraviolet Telescope (HUT) auroral spectrum and accounts for the H2 self-absorption as well as the methane absorption. It is found that no additional discrete soft electron precipitation is necessary to fit either the FUSE or the HUT observations. (C) 2004 Elsevier Inc. All rights reserved. [less ▲]

Detailed reference viewed: 33 (13 ULiège)
See detailJovian ion energy spectra - Ion stochastic acceleration by Alfven waves
Radioti, Aikaterini ULiege; Krupp, N.; Woch, J. et al

Conference (2005)

Detailed reference viewed: 5 (0 ULiège)
See detailJovian thermal structure inferred from the energy degradation of auroral electrons
Grodent, Denis ULiege; Gérard, Jean-Claude ULiege; Waite, J. H.

in Bulletin of the American Astronomical Society (1999, October 10)

A one--dimensional model has been developed to investigate the links between auroral heat input and the atmospheric temperature and composition structure of Jupiter. Different energy distributions are ... [more ▼]

A one--dimensional model has been developed to investigate the links between auroral heat input and the atmospheric temperature and composition structure of Jupiter. Different energy distributions are used to evaluate the importance of the energy spectrum of the incident electrons for the thermal balance of Jupiter's auroral thermosphere. Radiative cooling by H_3(+) and hydrocarbon (CH_4, C_2H_2) and downward conduction are calculated to solve the heat conduction equation. The values of observable quantities such as the altitude of the H_2 emission peak, infrared (IR) and ultraviolet (UV) emissions and temperatures associated with H_2 and H_3(+) optical signatures are used to constrain the parameters of the auroral electron energy distributions. From these simulations, it appears that the precipitated auroral energy is not able to directly provide the necessary heat to balance the hydrocarbon cooling below the homopause. It is suggested however that the auroral upper stratosphere is warmer than the equatorial upper stratosphere measured by Galileo. A Maxwellian energy distribution with a total flux of 20 ergs cm(-2) s(-1) and a characteristic energy of 22 keV added to a soft Maxwellian component of 1 erg cm(-2) s(-1) and 350 eV produces results in good agreement with thermospheric observations. [less ▲]

Detailed reference viewed: 18 (10 ULiège)
See detailJovian thermal structure inferred from the energy degradation of auroral electrons.
Grodent, Denis ULiege; Gérard, Jean-Claude ULiege; Waite, J H, Jr

in Bulletin of the American Astronomical Society (1999)

Detailed reference viewed: 13 (8 ULiège)
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See detailThe Jovian UV aurorae as seen by Juno-UVS
Bonfond, Bertrand ULiege; Gladstone, Randy; Grodent, Denis ULiege et al

Conference (2017, April 26)

The Juno spacecraft was inserted in orbit around Jupiter on July 4th 2016. Its highly elongated polar orbit brings it <5000 km above the cloud tops every 53,5 days, allowing spectacular and unprecedented ... [more ▼]

The Juno spacecraft was inserted in orbit around Jupiter on July 4th 2016. Its highly elongated polar orbit brings it <5000 km above the cloud tops every 53,5 days, allowing spectacular and unprecedented views of its polar aurorae. The Juno-UVS instrument is an imaging spectrograph observing perpendicularly to the Juno spin axis. It is equipped with a moving scan mirror at the entrance of the instrument that allows the field of view to be directed up to +/-30° away from the spin plane. The 70-205 nm bandpass comprises key UV auroral emissions such as the H2 bands and the H Lyman alpha line, as well as hydrocarbon absorption bands. We present polar maps of the aurorae at Jupiter for the first three first few periapses. These maps offer the first high resolution observations of the night-side aurorae. We will discuss the observed auroral morphology, including the satellite footprints, the outer emissions, the main emission and the polar emissions. We will also show maps of the color ratio, comparing the relative intensity of wavelengths subject to different degrees of absorption by CH4. Such measurements directly relate to the energy of the precipitating particles, since the more energetic the particles, the deeper they penetrate and the stronger the resulting methane absorption. For example, we will show evidence of longitudinal shifts between the brightness peaks and color ratio peaks in several auroral features. Such shifts may be interpreted as the result of the differential particle drift in plasma injection signatures. [less ▲]

Detailed reference viewed: 14 (1 ULiège)
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See detailJoyaux cosmiques - 01/2015
Manfroid, Jean ULiege

Article for general public (2015)

Jupiter en cyclope - Mars et la comète Siding Spring -L'amas ouvert NGC3532

Detailed reference viewed: 13 (0 ULiège)
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See detailJoyaux cosmiques - 01/2016
Manfroid, Jean ULiege

Article for general public (2016)

NGC 5291 - Sh2-310 et NGC 2362 - Tayna

Detailed reference viewed: 7 (0 ULiège)
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See detailJoyaux cosmiques - 02/2015
Manfroid, Jean ULiege

Article for general public (2015)

M31 - Messier 16 et les Piliers de la création -LDN 483, un trou dans le ciel

Detailed reference viewed: 9 (0 ULiège)
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See detailJoyaux cosmiques - 02/2016
Manfroid, Jean ULiege

Article for general public (2016)

La Lune - IDCS J1426 - HH24

Detailed reference viewed: 6 (0 ULiège)
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See detailJoyaux cosmiques - 03/2015
Manfroid, Jean ULiege

Article for general public (2015)

Le globule CG4 - La Tête de Cheval - La Nébuleuse Trifide -Smiley cosmique

Detailed reference viewed: 11 (0 ULiège)