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See detailThe Mars ultraviolet dayglow variability: SPICAM observations and model comparison
Gérard, Jean-Claude ULg; Cox, Cédric ULg; Bougher, S. W. et al

Conference (2009, September 16)

Limb profiles of the CO Cameron and CO2+ doublet airglow have been observed over different conditions (latitude, season, SZA, F10.7). They have been individually modelled using currently accepted cross ... [more ▼]

Limb profiles of the CO Cameron and CO2+ doublet airglow have been observed over different conditions (latitude, season, SZA, F10.7). They have been individually modelled using currently accepted cross sections, and outputs from the MTGCM. They have been shown to co-vary, with a ICO/ICO2+ ratio of about 4.7, less than the modelled ratio.The peak brightness varies linearly with the F10.7 solar flux proxy, in a way compatible with the Mariner 6 and 7 observations. The intensity of both emissions is overestimated by the model (but large uncertainties exist in excitation cross sections). An increase of the altitude of both emissions has been observed during the 2005 summer season. It is a consequence of the dust load, followed by an increased thermospheric CO2 density observed with SPICAV during the same period. This density enhancement is partly predicted by GCM models. [less ▲]

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See detailLa Marseillaise, ou le devenir d'un chant révolutionnaire en Wallonie.
Raxhon, Philippe ULg

Book published by Institut Jules Destrée (1998)

Detailed reference viewed: 39 (1 ULg)
See detailMarsick (Familie)
Pirenne, Christophe ULg

in Finscher, Ludwig (Ed.) Die Musik in Geschichte und Gegenwart (2004)

Detailed reference viewed: 7 (1 ULg)
Peer Reviewed
See detailMarsilio Ficino and Political Syncretism in Ian McEwan's Black Dogs
Delville, Michel ULg

in Notes on Contemporary Literature (1996), XXIV(3), 11-12

Detailed reference viewed: 160 (17 ULg)
See detailMarthe Moisset (1871-1945)
De Marco, Rosa ULg

in Allgemeines Künstlerlexikon (AKL) (2015)

Detailed reference viewed: 40 (4 ULg)
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See detailMartí "Taxista"
Dejasse, Erwin ULg

in 9e Art : Les Cahiers du Musée de la Bande Dessinée (2009), 15

Detailed reference viewed: 55 (1 ULg)
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See detailMartial : Livre 7. Édition - traduction - commentaire
Polis, Stéphane ULg

Master's dissertation (2002)

Detailed reference viewed: 146 (11 ULg)
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See detailThe Martian diffuse aurora: a model of ultraviolet and visible emissions
Gérard, Jean-Claude ULg; Soret, Lauriane ULg; Shematovich, V.I. et al

in Icarus (2017), 288

A new type of Martian aurora, characterized by an extended spatial distribution, an altitude lower than the discrete aurora and electron precipitation up to 200 keV has been observed following solar ... [more ▼]

A new type of Martian aurora, characterized by an extended spatial distribution, an altitude lower than the discrete aurora and electron precipitation up to 200 keV has been observed following solar activity on several occasions from the MAVEN spacecraft. We describe the results of Monte Carlo simulations of the production of several ultraviolet and violet auroral emissions for initial electron energies extending from 0.25 to 200 keV. These include the CO2+ ultraviolet doublet (UVD) at 288.3 and 289.6 nm and the Fox–Duffendack–Barker (FDB) bands, CO Cameron and Fourth Positive bands, OI 130.4 and 297.2 nm and CI 156.1 nm and 165.7 nm multiplets. We calculate the nadir and limb production rates of several of these emissions for a unit precipitated energy flux. Our results indicate that electrons in the range 50-200 keV produce maximum CO2+ UVD emission below 75 km, in agreement with the MAVEN observations. We calculate the efficiency of photon production per unit precipitated electron power. The strongest emissions are the CO2+ FDB, UVD and CO Cameron bands and the oxygen mission at 297.2 nm. The metastable a 3Π state which radiates the Cameron bands is deactivated by collisions below about 110 km. As a consequence, we show that the Cameron band emission is expected to peak at a higher altitude than the CO2+ UVD and FDB bands. Collisional quenching also causes the intensity ratio of the CO2+ UVD to CO Cameron bands to increase below ∼100 km in the energetic diffuse aurora. [less ▲]

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See detailThe Martian diffuse aurora: Monte Carlo simulations and comparison with IUVS-MAVEN observations
Gérard, Jean-Claude ULg; Soret, Lauriane ULg; Schneider, N. et al

Conference (2016, December)

A new type of Martian aurora, characterized by an extended spatial distribution, an altitude lower than the discrete aurora and electron precipitation up to 200 keV has been observed following solar ... [more ▼]

A new type of Martian aurora, characterized by an extended spatial distribution, an altitude lower than the discrete aurora and electron precipitation up to 200 keV has been observed following solar activity on several occasions with the IUVS on board the MAVEN spacecraft. We describe the results of Monte Carlo simulations of the production of several ultraviolet and visible auroral emissions for initial electron energies from 0.1 to 200 keV. These include the CO2+ ultraviolet doublet (UVD) at 288.3 and 289.6 nm and the Fox–Duffendack–Barker (FDB) bands, CO Cameron and Fourth Positive bands, OI 130.4 and 297.2 nm and CI 156.1 nm and 165.7 nm multiplets. We calculate the nadir and limb intensities of several of these emissions for a unit precipitated energy flux. Our results indicate that electrons in the range 100-200 keV produce maximum CO2+ UVD emission near 75 km. We combine SWEA and SEP electron energy spectra measured during diffuse aurora to calculate the volume emission rates and compare with IUVS observations of the emission limb profiles. The strongest predicted emissions are the CO2+ FDB, UVD and the CO Cameron bands. The metastable a 3Π state which radiates the Cameron bands is deactivated by collisions below ~110 km. As a consequence, we show that the CO2+ UVD to the Cameron bands ratio increases at low altitude in the energetic diffuse aurora. [less ▲]

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See detailMartian thermosphere scale height from SPICAM dayglow measurements
Stiepen, Arnaud ULg; Gérard, Jean-Claude; Bougher, Steve et al

Poster (2014)

We analyze the ultraviolet dayglow in the atmosphere of Mars through CO2+ and CO Cameron emissions. These emissions are accumulated on a large dataset of dayside grazing limb performed by the Spectroscopy ... [more ▼]

We analyze the ultraviolet dayglow in the atmosphere of Mars through CO2+ and CO Cameron emissions. These emissions are accumulated on a large dataset of dayside grazing limb performed by the Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) instrument on board the Mars Express spacecraft. The temperature of the Martian upper atmosphere can be retrieved from these limb emission profiles. We present discussion on the validity domain for such retrieval. We also show evidence for local (spatial and temporal) variability in the scale height of the atmosphere at the altitude of these emissions. [less ▲]

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See detailMartian thermospheric temperatures retrieved from CO2 + SPICAM dayglow measurements
Stiepen, Arnaud ULg; Gérard, Jean-Claude ULg; Bougher, S. et al

Conference (2012, December)

A large dataset of dayside grazing limb CO2+ observations performed by the SPICAM (Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars) instrument on board Mars Express is analyzed ... [more ▼]

A large dataset of dayside grazing limb CO2+ observations performed by the SPICAM (Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars) instrument on board Mars Express is analyzed to retrieve Martian thermospheric temperature, as well as its variation with solar activity, season and latitude. The method permits to retrieve the temperature from the scale height of the CO2+ emission. We also present puzzling features such as limb profiles exhibiting multiple peaks and their characteristics. We furthermore study the behavior of the main emission peak of the CO2+ vertical emission profiles. The CO2+ emission at 289 nm arises from the relaxation of the CO2+* molecule in the B2Σ+ state to the X2Π state. CO2+* molecules are mainly produced in the Martian dayside through photoionisation and photoelectron impact. The CO2+ emission exhibits features that constrain the temperature and density vertical profiles of CO2. Comparisons of retrieved temperatures are made with corresponding simulations from the coupled MGCM-MTGCM. We also use a Monte-Carlo code to model the observed intensity limb profiles. [less ▲]

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See detailMartian thermospheric temperatures retrieved from SPICAM dayglow measurements
Stiepen, Arnaud ULg; Gérard, Jean-Claude ULg; Montmessin, Franck et al

Poster (2013, October)

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See detailMARTIAN ULTRAVIOLET AURORA: RESULTS OF MODEL SIMULATIONS
Gérard, Jean-Claude ULg; Soret, Lauriane ULg; Shematovich, V.I. et al

Conference (2017, January)

We present recent modeling results based on observations performed with the UV spectrographs on board the Mars Express and MAVEN missions.Two types of aurora are discussed: the localized and transient ... [more ▼]

We present recent modeling results based on observations performed with the UV spectrographs on board the Mars Express and MAVEN missions.Two types of aurora are discussed: the localized and transient discrete aurora and the more stable diffuse aurora observed during periods of active solar periods. [less ▲]

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See detailMartian upper atmosphere response to solar EUV flux and soft X-ray flares
Jain, Sonal; Stewart, Ian; Schneider, Nicholas M. et al

in AAS/Division for Planetary Sciences Meeting Abstracts (2016, October 01)

Planetary upper atmosphere energetics is mainly governed by absorption of solar extreme ultraviolet (EUV) radiation. Understanding the response of planetary upper atmosphere to the daily, long and short ... [more ▼]

Planetary upper atmosphere energetics is mainly governed by absorption of solar extreme ultraviolet (EUV) radiation. Understanding the response of planetary upper atmosphere to the daily, long and short term variation in solar flux is very important to quantify energy budget of upper atmosphere. We report a comprehensive study of Mars dayglow observations made by the IUVS instrument aboard the MAVEN spacecraft, focusing on upper atmospheric response to solar EUV flux. Our analysis shows both short and long term effect of solar EUV flux on Martian thermospheric temperature. We find a significant drop (> 100 K) in thermospheric temperature between Ls = 218° and Ls = 140°, attributed primarily to the decrease in solar activity and increase in heliocentric distance. IUVS has observed response of Martian thermosphere to the 27-day solar flux variation due to solar rotation.We also report effect of two solar flare events (19 Oct. 2014 and 24 March 2015) on Martian dayglow observations. IUVS observed about ~25% increase in observed brightness of major ultraviolet dayglow emissions below 120 km, where most of the high energy photons (< 10 nm) deposit their energy. The results presented in this talk will help us better understand the role of EUV flux in total heat budget of Martian thermosphere. [less ▲]

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See detailMartin Heidegger, Extrait du dernier cours de Marbourg
Pieron, Julien ULg

in Philosophie (in press)

Detailed reference viewed: 66 (14 ULg)
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See detailMartin Hilpert, Construction Grammar and its Application to English
Brems, Lieselotte ULg

in English Text Construction (2015), 8(1), 132-136

Detailed reference viewed: 236 (3 ULg)
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See detailMartin le bien nommé !
Libois, Roland ULg

Learning material (1994)

Detailed reference viewed: 19 (2 ULg)