References of "Gladstone, G. R."
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See detailThe morphology of the X-ray emission above 2 keV from Jupiter's aurorae
Elsner, R. F.; Branduardi-Raymont, G.; Galand, M. et al

Conference (2007, June 25)

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See detailVenus' ultraviolet airglow and aurora: Monte Carlo simulations and comparison with observations
Gérard, Jean-Claude ULiege; Shematovich, V. I.; Bisikalo, D. V. et al

in European Planetary Science Congress 2006 (2006)

The Venus airglow has been observed from spectrometers on board rockets probes and satellites such as OUVS on Pioneer Venus Venera Galileo HUT on the Space Shuttle and quite recently SPICAV on Venus ... [more ▼]

The Venus airglow has been observed from spectrometers on board rockets probes and satellites such as OUVS on Pioneer Venus Venera Galileo HUT on the Space Shuttle and quite recently SPICAV on Venus Express The spectrum is dominated by emissions from helium hydrogen oxygen and carbon lines and CO bands Localized emissions of OI at 1304 and 1356 A have been sporadically observed on the nightside and are likely caused by precipitation of auroral electrons in the wake of the planet We have developed a Monte Carlo code solving the Boltzmann equation for energetic electrons to calculate the energy distribution function and fluxes of primary and secondary auroral electrons and for photoelectrons The model is used to calculate the vertical distribution of the excitation rate of various excited states For optically thick transitions such as the 3P-3S triplet at 1304 A a radiative transfert code is used to calculate the emergent emission rate We find that the relative intensity of the oxygen and CO Cameron band emissions is a sensitive indicator of the energy of auroral electrons The observed values indicate that the mean energy is on the order of 10-50 eV Dayglow intensity and distributions are also compared with observed characteristics [less ▲]

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See detailSpectral Analysis of HST-STIS Observations of Jovian UV Auroral Emissions
Gladstone, G. R.; Gérard, Jean-Claude ULiege; Gustin, Jacques ULiege et al

Conference (2005, August 01)

Spectral observations of Jupiter's far-ultraviolet (FUV) auroral emissions are commonly used to determine a ``color ratio, - defined as I(155-162nm) / I(123-130nm), which provides an estimate for the peak ... [more ▼]

Spectral observations of Jupiter's far-ultraviolet (FUV) auroral emissions are commonly used to determine a ``color ratio, - defined as I(155-162nm) / I(123-130nm), which provides an estimate for the peak emission altitude of the aurora and thus, assuming an accurate model atmosphere, for the mean energy of precipitating electrons. This is because the nascent emission spectrum resulting from electron impact on H[SUB]2[/SUB] is relatively unchanging over a wide range of energy, so that differential absorption by overlying CH[SUB]4[/SUB] is the primary modifier of the spectral shape of the emergent FUV emissions. This method is analogous to that used at Earth, with N[SUB]2[/SUB] LBH auroral emissions instead of H[SUB]2[/SUB] Lyman and Werner bands and differential absorption by O[SUB]2[/SUB] rather than methane. More detailed simulations of Jupiter's FUV auroral spectra can be used to place useful constraints on higher hydrocarbons, such as acetylene and ethane. Here we present a spectral analysis of HST-STIS G140L observations taken in September 1999, which include a region with the largest color ratio yet observed (i.e., the deepest aurora). A non-linear least squares model fit to the data is used to search for the presence of several important overlying hydrocarbons with strong and distinctive FUV absorption cross sections, e.g., CH[SUB]4[/SUB], C[SUB]2[/SUB]H[SUB]2[/SUB], C[SUB]2[/SUB]H[SUB]4[/SUB], C[SUB]2[/SUB]H[SUB]6[/SUB], CH[SUB]3[/SUB]C[SUB]2[/SUB]H, C[SUB]3[/SUB]H[SUB]8[/SUB], C[SUB]4[/SUB]H[SUB]2[/SUB], C[SUB]2[/SUB]H[SUB]2[/SUB], and C[SUB]4[/SUB]H[SUB]10[/SUB]. We gratefully acknowledge support from NASA through grant NNG05GG97G. [less ▲]

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See detailSimultaneous Chandra X-ray, HST UV, and Ulysses Radio Observations of Jupiter's Aurora
Elsner, R. F.; Bhardwaj, A.; Waite, J. H. et al

Poster (2004)

Observations of Jupiter carried out by the Chandra ACIS-S instrument over 24-26 February, 2003, show that the auroral X-ray spectrum consists of line emission consistent with high-charge states of ... [more ▼]

Observations of Jupiter carried out by the Chandra ACIS-S instrument over 24-26 February, 2003, show that the auroral X-ray spectrum consists of line emission consistent with high-charge states of precipitating ions, and not a continuum as might be expected from bremsstrahlung. The part of the spectrum due to oxygen peaks around 650 eV, which indicates a high fraction of fully-stripped oxygen in the precipitating ion flux. The OVIII emission lines at 653 eV and 774 eV, as well as the OVII emission lines at 561 eV and 666 eV, are clearly identified. There is also line emission at lower energies in the spectral region extending from 250 to 350 eV for which sulfur and carbon lines are possible candidates. The Jovian auroral spectra differ significantly from measured cometary X-ray spectra. The charge state distribution of the oxygen ion emission evident in the measured auroral spectra strongly suggests that, independent of the source of the energetic ions (magnetospheric or solar wind) the ions have undergone additional acceleration. For the magnetospheric case, acceleration to energies exceeding 10 MeV is apparently required. The ion acceleration also helps to explain the high intensities of the X-rays observed. The phase space densities of unaccelerated source populations of either solar wind or magnetospheric ions are orders of magnitude too small to explain the observed emissions. The Chandra X-ray observations were executed simultaneously with observations at ultraviolet wavelengths by the Hubble Space Telescope and at radio wavelengths by the Ulysses spacecraft. These additional data sets provide interesting hints as to the location of the source region and the acceleration characteristics of the generation mechanism. The combined observations suggest that the source of the X rays is magnetospheric in origin, and that strong field-aligned electric fields are present which simultaneously create both the several-MeV energetic ion population and the relativistic electrons believed to be responsible for the generation of 40 minute quasi-periodic radio outbursts. [less ▲]

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See detailSummary of quantitative interpretation of IMAGE far ultraviolet auroral data
Frey, H. U.; Mende, S. B.; Immel, T. J. et al

in Space Science Reviews (2003), 109

Direct imaging of the magnetosphere by instruments on the IMAGE spacecraft is supplemented by simultaneous observations of the global aurora in three far ultraviolet (FUV) wavelength bands. The purpose of ... [more ▼]

Direct imaging of the magnetosphere by instruments on the IMAGE spacecraft is supplemented by simultaneous observations of the global aurora in three far ultraviolet (FUV) wavelength bands. The purpose of the multi-wavelength imaging is to study the global auroral particle and energy input from the magnetosphere into the atmosphere. This paper describes the method for quantitative interpretation of FUV measurements. The Wide-Band Imaging Camera (WIC) provides broad band ultraviolet images of the aurora with maximum spatial resolution by imaging the nitrogen lines and bands between 140 and 180 nm wavelength. The Spectrographic Imager (SI), a dual wavelength monochromatic instrument, images both Doppler-shifted Lyman-alpha emissions produced by precipitating protons, in the SI-12 channel and OI 135.6 nm emissions in the SI-13 channel. From the SI-12 Doppler shifted Lyman-alpha images it is possible to obtain the precipitating proton flux provided assumptions are made regarding the mean energy of the protons. Knowledge of the proton (flux and energy) component allows the calculation of the contribution produced by protons in the WIC and SI-13 instruments. Comparison of the corrected WIC and SI-13 signals provides a measure of the electron mean energy, which can then be used to determine the electron energy flux. To accomplish this, reliable emission modeling and instrument calibrations are required. In-flight calibration using early-type stars was used to validate the pre-flight laboratory calibrations and determine long-term trends in sensitivity. In general, very reasonable agreement is found between in-situ measurements and remote quantitative determinations. [less ▲]

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See detailA new FUV auroral feature on Jupiter
Grodent, Denis ULiege; Gladstone, G. R.; Gérard, Jean-Claude ULiege et al

Conference (2003, April 01)

In December 2000, a series of HST/STIS FUV images of Jupiter's north auroral region displayed bright transient spots located near local midnight. In the images taken at CML Ë 220[SUP]o[/SUP] the spots ... [more ▼]

In December 2000, a series of HST/STIS FUV images of Jupiter's north auroral region displayed bright transient spots located near local midnight. In the images taken at CML Ë 220[SUP]o[/SUP] the spots (one or two) appear near the limb, poleward and equatorward of the main auroral oval, at latitude Ë 73[SUP]o[/SUP] and λ[SUB]III[/SUB] longitude Ë 145[SUP]o[/SUP]. The dimensions of each spot are very small, about 1[SUP]o[/SUP] in latitude and 5[SUP]o[/SUP] in longitude, which is about the size of the footprint of the Io satellite. However, the analysis of the position of the Galilean satellites and of known small-bodies (comets, asteroids) shows that these spots are not magnetically associated with any of these objects. The emitted power of the spots is variable and can reach several GW (more than the power emitted at the Io footprint). The lightcurves derived from multiple images are consistent with spots disappearing behind the planetary limb as the planet rotates. In addition, one short time-tagged image undoubtedly shows a bright double--spot feature pulsating with a period of 300 s. According to the VIP4 magnetic model, the auroral spots map along field lines down to the jovian magnetosphere in a small region roughly located near midnight at distances larger than 60~R_J. At these distances, a 1[SUP]o[/SUP] by 5[SUP]o[/SUP] auroral spot subtends an equatorial region smaller than 10~R_J by 10~R_J . Consequently, the auroral spots cannot be directly associated with large scale process involving the whole magnetotail but rather with localized events. [less ▲]

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See detailPreliminary Results from Recent Simultaneous Chandra/HST Observations of Jupiter Auroral Zones
Elsner, R. F.; Gladstone, G. R.; Waite, J. H. et al

Poster (2003)

Jupiter was observed by the Chandra X-ray Observatory in late February, 2003, for 144 ks, using both the ACIS-S and HRC-I imaging x-ray cameras. Five orbits of HST STIS observations of the planet's ... [more ▼]

Jupiter was observed by the Chandra X-ray Observatory in late February, 2003, for 144 ks, using both the ACIS-S and HRC-I imaging x-ray cameras. Five orbits of HST STIS observations of the planet's northern auroral zone were obtained during the ACIS-S observations. These data are providing a wealth of information about Jupiter's auroral activity, including the first x-ray spectra from the x-ray hot spots inside the auroral ovals. We will also discuss time variability in the auroral x-ray emission and a possible phase relation between the emission from the northern and southern x-ray aurora. [less ▲]

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See detailThe HST Campaign on Jupiter's Aurora during the Cassini Flyby
Clarke, J. T.; Grodent, Denis ULiege; Waite, J. H. et al

Conference (2002, July 29)

Detailed reference viewed: 12 (4 ULiège)
See detailThe HST Campaign on Jupiter's Aurora during the Cassini Flyby
Clarke, J. T.; Grodent, Denis ULiege; Gérard, Jean-Claude ULiege et al

Conference (2002, June 17)

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See detailIMAGE and FAST observations of substorm recovery phase aurora
Mende, Stephen B; Frey, Harald U; Carlson, Charles W et al

in Geophysical Research Letters (2002), 29

Images from the IMAGE Wide-band Imaging Camera (WIC) and Spectrographic Imager (SI) channel SI12, were compared to in situ data taken by FAST. The IMAGE data segment began during the expansive phase of a ... [more ▼]

Images from the IMAGE Wide-band Imaging Camera (WIC) and Spectrographic Imager (SI) channel SI12, were compared to in situ data taken by FAST. The IMAGE data segment began during the expansive phase of a substorm and a double oval configuration evolved, consisting of a set of discrete poleward auroral forms and a separate more diffuse oval. The FAST data showed that a narrow (~1.5° latitude) region of downward currents separated the two ovals. The SI-12 optical observations showed a single oval of precipitating protons located on the equatorward side within the diffuse aurora. In agreement with IMAGE, the highest intensity proton flux measured by FAST was concentrated on the equatorward region although low flux protons were present throughout the entire double oval. In the lower latitude diffuse oval occasional structured auroras were embedded. These structured auroras were mostly created by inverted V type electrons but there were narrow regions in which intense beams of accelerated electrons were seen whose energy/pitch angle distribution and accompanying electric field data were consistent with Alfven wave acceleration. The poleward oval consisted of an intense inverted V precipitation event poleward of which a weak region of Alfven wave accelerated electrons was located. From the images it appears that the Alfven wave accelerated electron event in the diffuse auroral regions and the poleward features were part of short lived or rapidly moving auroral forms. [less ▲]

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See detailChandra X-ray Observations of the Jovian System
Elsner, R. F.; Waite, J. H.; Crary, F. et al

Conference (2002)

High-spatial resolution Chandra x-ray obsrvations have demonstrated that most of Jupiter's northern auroral x-rays come from a hot spot located significantly poleward of the latitudes connected to the ... [more ▼]

High-spatial resolution Chandra x-ray obsrvations have demonstrated that most of Jupiter's northern auroral x-rays come from a hot spot located significantly poleward of the latitudes connected to the inner magnetosphere. This hot spot appears fixed in magnetic latitude and longitude and coincides with a region exhibiting anomalous ultraviolet and infrared emissions. The hot spot also exhibited approximately 45 minute quasi-periodic oscillations, a period similar to those reported for high-latitude radio and energetic electron bursts observed by near-Jupiter spacecraft. These results invalidate the idea that jovian auroral x-ray emissions are mainly excited by steady precipitation of energetic heavy ions from the inner magnetosphere. Instead, the x-rays appear to result from currently unexplained processes in the outer magnetosphere that produce highly localized and highly variable emissions over an extremely wide range of wavelengths. The Chandra observations also revealed for the first time x-ray emission (about 0.1 GW) from the Io Plasma Torus, as well as very faint x-ray emission (about 1-2 MW) from the Galilean moons Io, Europa, and possibly Ganymede. The emission from the moons is almost certainly due to Kalpha emission of surface atoms (and possibly impact atoms) excited by the impact of highly energetic protons, oxygen, and sulfur atoms and ions from the Torus. The Torus emission is less well understood at present, although bremsstrahlung from the non-thermal tail of the electron distribution may provide a significant fraction. In any case, further observations, already accepted and in the process of being planned, with Chandra, some with the moderate energy resolution of the CCD camera, together with simultaneous Hubble Space Telescope observations and hopefully ground-based IRTF observations should soon provide greater insight into these various processes. [less ▲]

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See detailSoft X-ray emissions from planets, moons, and comets
Bhardwaj, A.; Gladstone, G. R.; Elsner, R. F. et al

Conference (2002)

A wide variety of solar system bodies are now known to radiate in the soft X-ray energy (<5 keV) regime. These include planets (Earth, Jupiter, Venus, Saturn, Mars): bodies having thick atmospheres, with ... [more ▼]

A wide variety of solar system bodies are now known to radiate in the soft X-ray energy (<5 keV) regime. These include planets (Earth, Jupiter, Venus, Saturn, Mars): bodies having thick atmospheres, with or without intrinsic magnetic field; planetary satellites (Moon, Io, Europa, Ganymede): bodies with thin or no atmospheres; and comets and Io plasma torus: bodies having extended tenuous atmospheres. Several different mechanisms have been proposed to explain the generation of soft X-rays from these objects, whereas in the hard X-ray energy range (>10 keV) X-rays mainly result from the electron bremsstrahlung process. In this paper we present a brief review of the X-ray observations on each of the planetary bodies and discuss their characteristics and proposed source mechanisms. [less ▲]

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See detailObservations of the Jovian System with the Chandra X-ray Observatory
Elsner, R. F.; Gladstone, G. R.; Lewis, W. S. et al

Conference (2002)

Sensitive, very high spatial-resolution x-ray observations with the Chandra X-ray Observatory have revealed that Jupiter's northern x-ray aurora originates at a spot fixed in a coordinate system rotating ... [more ▼]

Sensitive, very high spatial-resolution x-ray observations with the Chandra X-ray Observatory have revealed that Jupiter's northern x-ray aurora originates at a spot fixed in a coordinate system rotating with the planet at latitude (60-70 deg north) and longitude (160-180 deg System III). The northern auroral x-ray emission varies with a period about 45 minute and has an average power of about 1 GW. Jupiter's disk also emits x-rays with a power of about 2 GW, perhaps resulting from reprocessing of solar x-rays in its atmosphere. These observations reveal for the first time x-ray emission from the Io Plasma Torus, with a power of about 0.1 GW. Finally, we report the discovery of very faint (about 1-2 MW) soft x-ray emission from the Galilean satellites Io, Europa, and probably Ganymede. [less ▲]

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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)

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See detailChandra HRC Observations of X-rays from the Jupiter System
Gladstone, G. R.; Waite, J. H.; Grodent, Denis ULiege et al

Conference (2001, June 25)

Detailed reference viewed: 8 (0 ULiège)
See detailOverview of Ionospheric-Magnetospheric Coupling at Jupiter: The Jovian Aurora
Waite, J. H.; Grodent, Denis ULiege; Crary, F. et al

Conference (2001, June 25)

Detailed reference viewed: 7 (0 ULiège)
See detailDetermination of electron and proton auroral energy inputs from FUV-IMAGE
Gérard, Jean-Claude ULiege; Hubert, Benoît ULiege; Meurant, M. et al

Conference (2001, May 01)

The FUV experiment onboard the IMAGE spacecraft offers the unique possibility to obtain simultaneous snapshots of the global north aurora every 2 minutes in three different spectral channels. The WIC ... [more ▼]

The FUV experiment onboard the IMAGE spacecraft offers the unique possibility to obtain simultaneous snapshots of the global north aurora every 2 minutes in three different spectral channels. The WIC camera has a broadband channel covering the 135-190 nm interval including the N[SUB]2[/SUB] LBH bands, part of which may be absorbed by O[SUB]2[/SUB]. The SI13 channel is centered on the OI 135.6 nm line which is optically thin and includes a ~ 40% LBH contribution. Finally, the SI12 camera images the Doppler-shifted Ly-α emission excited by the proton aurora. This set of instrumentation is combined with auroral models to determine the electron and the proton energy fluxes from the magnetosphere. Examples will be presented and compared with the values deduced from the NOAA satellites. Simultaneous in-situ measurements of the particle characteristic energy have been combined with the data extracted from the FUV images to validate the models and derive empirical relationships between the particle flux measured by the detectors and the brightness observed by FUV-IMAGE at the footprint of the same magnetic field line. Finally, we will assess the ability to deduce the characteristic energy of the auroral particles from the ratio of co-registered images in the WIC and SI13 cameras. This method is based on the difference of vertical distribution of the LBH and the OI 135.6 nm emissions. It offers the potential to globally remotely sense not only the energy flux from the magnetosphere but also the main features of the electron characteristic energy. [less ▲]

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See detailThe Forty-Minute Period of Jupiter's X-ray Polar Emission
Grodent, Denis ULiege; Crary, F. J.; Gladstone, G. R. et al

Poster (2001)

The observation of Jupiter's x-ray auroral emission during the Cassini Jupiter flyby has brought information of prime interest. The High Resolution Camera onboard the Chandra satellite has a pixel size of ... [more ▼]

The observation of Jupiter's x-ray auroral emission during the Cassini Jupiter flyby has brought information of prime interest. The High Resolution Camera onboard the Chandra satellite has a pixel size of ~.13 arcsec, which makes it possible to discriminate emission features inside the Jovian polar regions. A ten-hour (one full Jovian rotation) light curve of the northern polar cap region (i.e. a region enclosed by System-3 longitude 160-180° and latitude 60-70°) clearly shows a forty-minute oscillation. This oscillation is shown to be independent of the viewing geometry. Such an oscillation is more speculative for the southern polar cap for which the S/N is much lower than in the North. However, if statistically significant, the fluctuation observed in the southern cap may be in close anticorrelation with the northern cap light curve. This would suggest a bouncing motion of the impinging particles, presumably sulfur and oxygen ions, between the polar cap mirror points. Comparison with HST-STIS far ultraviolet (FUV) observations taken during this Jovian rotation allows us to correlate the x-ray emission with a persistent FUV feature mapping to ~30 RJ in the dayside magnetosphere. This feature shows significant local time variations. However, the sampling of the STIS observations does not permit us to highlight a forty-minute oscillation in the corresponding ultraviolet light curve. Previous STIS spectra favor a high FUV color ratio for the polar cap emission, which is consistent with precipitation of high energy sulfur and oxygen ions. [less ▲]

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See detailObservations of the Jovian low latitude FUV emission with HST/STIS
Gustin, Jacques ULiege; Grodent, Denis ULiege; Dols, V. et al

Poster (1999, October 10)

Detailed reference viewed: 7 (1 ULiège)
See detailFar ultraviolet Observations of Jovian low latitude regions with HST/STIS
Gustin, Jacques ULiege; Grodent, Denis ULiege; Gérard, Jean-Claude ULiege et al

in Bulletin of the American Astronomical Society (1999, September 01), 30(11),

Far ultraviolet observations of the Jovian disk were made at low and mid-latitudes with FUV MAMA/STIS on board HST in January 1999 both in the imaging and spectroscopic modes. An image was obtained with ... [more ▼]

Far ultraviolet observations of the Jovian disk were made at low and mid-latitudes with FUV MAMA/STIS on board HST in January 1999 both in the imaging and spectroscopic modes. An image was obtained with the Lyalpha filter in the hydrogen bulge region for comparison with the expected Lyman-alpha brightness distribution for Ly-alpha resonance scattering. Other images in the 1200-1700 { Angstroms} region show band structures parallel to the equator with fading contrast toward the center and the limb. Spectroscopic observations were made in the 1200-1700 { Angstroms} (G140L) and 1245-1298 { Angstroms} (G140M) regions at ~ 5 { Angstroms} resolution to map the H_2 airglow and the UV absorbents along the STIS slit. Preliminary results indicate that a C_2H_2 absorption signature is clearly observed in the solar ultraviolet reflected spectrum. The ethylene absorption may be mapped to derive variations of the acetylene abundance. The H_2 FUV airglow shows both the fluorescence and the electron impact components. Its spatial variation is described and compared with the expected airglow distribution. We acknowledge funding by NASA and by the PRODEX program of the European space agency. [less ▲]

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