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See detailObservations of CH4, CH3D and H2CO at Ile de La Réunion from ground-based FTIR and MAXDOAS campaign measurements
Vigouroux, Corinne; De Mazière, Martine; Van Roozendael, Michel et al

Poster (2007, November)

Ile de La Réunion (21°S, 55°E) is candidate to become a primary station the ground-based Network for the Detection of Atmospheric Composition Change (NDACC) which was formed to provide long-term ... [more ▼]

Ile de La Réunion (21°S, 55°E) is candidate to become a primary station the ground-based Network for the Detection of Atmospheric Composition Change (NDACC) which was formed to provide long-term monitoring of atmospheric trace gases at globally distributed sites. Ground-based network data are also very valuable for the validation of satellite data, such as SCIAMACHY, ACE-FTS and IASI. Up to now, only a few NDACC stations are located in the Southern Hemisphere, and none of them is at subtropical latitude. Three campaigns of FTIR measurements were made at the Ile de La Réunion in preparation of a near future permanent installation, namely in October 2002, from August to October 2004, and from May to November 2007. A UV-visible Multi-Axis DOAS (MAXDOAS) instrument was operated at the same site from July 2004 to June 2005. The inversion algorithms for both the MAXDOAS and FTIR spectral data analyses use the Optimal Estimation Method to derive information about the vertical distribution of the target gases. We will present the vertical profiles and total columns of the greenhouse gas CH4 and its isotopologue CH3D, obtained from the FTIR measurements. For the latter, the number of degrees of freedom for signal is close to one, limiting the information to the total column abundance. Early comparisons with correlative measurements from satellite data will be discussed. Formaldehyde (H2CO) is a source of HOx and an indicator for biogenic emissions, biomass burning, and anthropogenic pollution. It can be measured by both the FTIR and UV-Visible MAXDOAS instruments. The total columns obtained by the two techniques in the common period of measurements August-October 2004 will be discussed. We will also show the comparisons of the time series for formaldehyde from both instruments with correlative SCIAMACHY data above La Réunion. [less ▲]

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See detailObservations of CN and dust activity of comet 9P/Tempel 1 around Deep Impact
Rauer, H.; Weiler, M.; Sterken, C. et al

in Astronomy and Astrophysics (2006), 459

Aims.We present observations of CN emission and the scattered solar light on cometary dust particles around the impact time of the Deep Space spacecraft (NASA) into the nucleus of comet 9P/Tempel 1. The ... [more ▼]

Aims.We present observations of CN emission and the scattered solar light on cometary dust particles around the impact time of the Deep Space spacecraft (NASA) into the nucleus of comet 9P/Tempel 1. The purpose of the observations was to compare post-impact activity to the conditions pre-impact to search for new spectral emission lines after impact, to quantify the increase in gas activity due to the impact and to study the long-term activity changes.<BR /> Methods: .We performed long-slit spectroscopy observations of comet 9P/Tempel 1 at the VLT, ESO, using the FORS instruments from July 2 to July 12, 2005. A wavelengths range of 370-920 nm was covered using two grisms. Four different position angle settings of the slit were applied each night with the projected Sun-comet line as standard setting, for which we report results here.<BR /> Results: .The optical spectra of comet 9P/Tempel 1 showed the usual emission bands in the optical wavelengths range of the radicals: CN, C3, C2 and NH2. No new emission bands were detected after impact. The ejecta cloud of gas and dust caused by the impacting spacecraft into the cometary nucleus could be followed over the observing period. The projected expansion velocities have been determined. The night after impact we observed about (3.9 ± 1.2) × 10[SUP]29[/SUP] molecules of the CN parent in the ejected cloud. However, after five days the appearance of the gas and dust coma was back to pre-impact conditions. <BR /> [less ▲]

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See detailObservations of Comet 73P/SW3 close to its closest approach to the Earth.
Tozzi, G. P.; Bagnulo, S.; Boehnhardt, H. et al

in European Planetary Science Congress 2006 (2006)

In May 2006 comet 73P/SW3 passed at less than 0.1 AU from Earth providing us an unique opportunity for high spatial resolution study of its coma. This event was expected to be particularly interesting ... [more ▼]

In May 2006 comet 73P/SW3 passed at less than 0.1 AU from Earth providing us an unique opportunity for high spatial resolution study of its coma. This event was expected to be particularly interesting because the comet had broken apart in 3-4 fragments in 1996. The 2006 apparition has been even more interesting because the fragments produced in 1996, when approaching the Sun, were continuously breaking apart. This process resulted in many small sub-fragments and in the injection in the coma of fresh material, coming from the interior of the nuclei, giving the possibility to study this uncontaminated material. The breaking fragments have been observed at ESO in the visible and near-IR with the aim of analyzing this fresh solid component of the coma in search of possible presence of organic solids. In the presentation we will report preliminary results of this campaign. [less ▲]

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See detailObservations of comet McNaught from La Silla
Snodgrass, C.; Jehin, Emmanuel ULg; Fitzsimmons, A. et al

Poster (2007)

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See detailObservations of Coronal Structures Above an Active Region by EIT and Implications for Coronal Energy Deposition
Neupert, W. M.; Newmark, J.; Delaboudinière, J.-P. et al

in Solar Physics (1998), 183

Solar EUV images recorded by the EUV Imaging Telescope (EIT) on SOHO have been used to evaluate temperature and density as a function of position in two largescale features in the corona observed in the ... [more ▼]

Solar EUV images recorded by the EUV Imaging Telescope (EIT) on SOHO have been used to evaluate temperature and density as a function of position in two largescale features in the corona observed in the temperature range of 1.0-2.0MK. Such observations permit estimates of longitudinal temperature gradients (if present) in the corona and, consequently, estimates of thermal conduction and radiative losses as a function of position in the features. We examine two relatively cool features as recorded in EIT's Feix/x (171Å) and Fexii (195Å) bands in a decaying active region. The first is a long-lived loop-like feature with one leg, ending in the active region, much more prominent than one or more distant footpoints assumed to be rooted in regions of weakly enhanced field. The other is a near-radial feature, observed at the West limb, which may be either the base of a very high loop or the base of a helmet streamer. We evaluate energy requirements to support a steady-state energy balance in these features and find in both instances that downward thermal conductive losses (at heights above the transition region) are inadequate to support local radiative losses, which are the predominant loss mechanism. The requirement that a coronal energy deposition rate proportional to the square of the ambient electron density (or pressure) is present in these cool coronal features provides an additional constraint on coronal heating mechanisms. [less ▲]

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See detailObservations of equatorward patchy auroral ultraviolet emissions
Dumont, Maïté ULg; Grodent, Denis ULg; Radioti, Aikaterini ULg et al

Conference (2012, May 25)

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See detailObservations of halogens, CO, CH4, and H2CO at Ile de La Réunion from ground-based FTIR and MAXDOAS campaign measurements
De Mazière, Martine; Vigouroux, Corinne; Hendrick, François et al

Poster (2008, April)

Ile de La Réunion is a complementary site in the Network for the Detection of Atmospheric Composition Change (NDACC), situated in the southern tropics, at 21°S, 55°E. In support of a better understanding ... [more ▼]

Ile de La Réunion is a complementary site in the Network for the Detection of Atmospheric Composition Change (NDACC), situated in the southern tropics, at 21°S, 55°E. In support of a better understanding of atmospheric chemistry and physics above tropical regions, we have implemented new ground-based MAX-DOAS (multi-axis DOAS) and FTIR (Fourier transform infrared) observations at this site, on a campaign basis since 2002. At present, we have data from 2002 (month of October), 2004 (August to October) and 2007 (end of May until the end of October). Additional campaigns are planned until the availability of a new infrastructure for permanent observations at the Maido (~ 2000 masl), around 2010. Here, we report on the available time series for a number of tropospheric species (CO, H2CO and CH4,) and stratospheric halogen species, comparisons between MAX-DOAS and FTIR data of H2CO, and comparisons of ground-based and satellite data. [less ▲]

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See detailObservations of high redshift QSO’s
Swings, Jean-Pierre ULg; Surdej, Jean ULg

in The Messenger (1978), 15

Time-consuming observations with existing large telescopes have shown that the spectra of quasistellar objects are exceedingly complex. A VLT is needed to obtain the highest spectral resolution and to ... [more ▼]

Time-consuming observations with existing large telescopes have shown that the spectra of quasistellar objects are exceedingly complex. A VLT is needed to obtain the highest spectral resolution and to study in detail the numerous absorption lines. Drs. Jean-Pierre Swings (Institut d'Astrophysique in Liege, Belgium) and Jean Surdej (ESO) would like to use their nights to investigate the nature ofsome of the most distant objects in the universe. [less ▲]

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See detailObservations of jovian polar auroral filaments
Nichols; Clarke; Gérard et al

Poster (2009, July 27)

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See detailObservations of Jovian polar auroral filaments
Nichols, J. D.; Clarke, J. T.; Gérard, Jean-Claude ULg et al

in Geophysical Research Letters (2009), 36

In this paper we report a phenomenon hitherto unobserved in Jupiter's ultraviolet polar auroras, specifically thin (~0.6° wide), long-lived quasi-sun-aligned polar auroral filaments (PAFs) of brightness ... [more ▼]

In this paper we report a phenomenon hitherto unobserved in Jupiter's ultraviolet polar auroras, specifically thin (~0.6° wide), long-lived quasi-sun-aligned polar auroral filaments (PAFs) of brightness ~100 kR spanning the highly variable region poleward of the main oval. This observation, made using Hubble Space Telescope images, is significant since no coherent structures have previously been observed in Jupiter's very high latitude auroral region, and it may help shed light on the dynamics of Jupiter's under-explored magnetotail. PAFs have been observed in 4 sets of observations over 6 days in 2007, and their occurrence appears to be independent of impinging solar wind conditions. The feature comprises two components: the section toward noon remains fixed in orientation toward the sun, while the anti-sunward section rotates. We estimate overall rotation rates of ~0--45% of corotation, values which may indicate the rotation rate of Jupiter's polar ionosphere and tail lobes. [less ▲]

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See detailObservations of long-lived anthropogenic halocarbons at the high-Alpine site of Jungfraujoch (Switzerland) for assessment of trends and European sources
Reimann, Stefan; Vollmer, M. K.; Folini, Doris et al

in Science of the Total Environment (2008), 391

Anthropogenic halocarbons, such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), bromocarbons (halons) and long-lived chlorinated solvents have been measured ... [more ▼]

Anthropogenic halocarbons, such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), bromocarbons (halons) and long-lived chlorinated solvents have been measured continuously at the high-Alpine site of Jungfraujoch (Switzerland) since January 2000. Chloro- and bromo-containing halocarbons are responsible for the stratospheric ozone depletion and will be globally banned from usage within the next years. With the exception of the stable CFC-12 (CF2Cl2), all major CFCs and chlorinated solvents show a negative trend in recent years in their background concentrations at Jungfraujoch. HCFCs, as their first-generation substitute, are still increasing with a few percent per year. However, the frequency and the strength of HCFCs pollution events, which are caused by regional European emissions, are already declining. This can be seen as a sign of the impending ban of these gases within the next years in Europe. On the other hand, HFCs as the second-generation substitutes, are increasing with relative rates of at least 10% per year (e.g. almost 5 ppt per year for HFC-134a). An allocation of European sources was attempted by combining measured concentrations with trajectories of air masses reaching the Jungfraujoch during pollution events. Potential source regions could be detected in Italy, France, Spain and Germany. [less ▲]

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See detailObservations of nebulae ejected by massive stars with PACS
Vamvatira-Nakou, Chloi ULg; Royer, P.; Hutsemekers, Damien ULg et al

Poster (2010)

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See detailObservations of O(1D) and N(2D) emission in the polar aurora
Gérard, Jean-Claude ULg; HARANG, Ove E

in Physics and chemistry of upper atmospheres (1973)

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See detailObservations of Red Giants in the Cluster NGC 6633 by the CoRoT Space Mission and the HARPS and SOPHIE Spectrometers
Barban, C.; Baudin, F.; Poretti, E. et al

in Astronomical Society of the Pacific Conference Series (2013, December 01)

The CoRoT space mission and the HARPS and SOPHIE ground-based spectrometers have observed red giants belonging to the open cluster NGC 6633. Solar-like oscillations are detected in the CoRoT data obtained ... [more ▼]

The CoRoT space mission and the HARPS and SOPHIE ground-based spectrometers have observed red giants belonging to the open cluster NGC 6633. Solar-like oscillations are detected in the CoRoT data obtained for four red giants. Spectroscopic data questions the cluster membership of one of these stars. The combination of these photometric and spectroscopic data will be a unique opportunity to estimate their global parameters as well as to probe their internal structure. [less ▲]

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See detailObservations of Saturn's Atmosphere and Auroras by Cassini UVIS and VIMS
Pryor, W. R.; Baines, K.; West, R. et al

Conference (2005, December 01)

Cassini's Ultraviolet Imaging Spectrograph (UVIS) has completed a year of study of Saturn's atmosphere and auroras. Two long slit spectral channels are used to obtain EUV data from 56.3-118.2 nm and FUV ... [more ▼]

Cassini's Ultraviolet Imaging Spectrograph (UVIS) has completed a year of study of Saturn's atmosphere and auroras. Two long slit spectral channels are used to obtain EUV data from 56.3-118.2 nm and FUV data from 111.5-191.3 nm. 64 spatial pixels along each slit are combined with slit motion to build up spectral images of Saturn, with sufficient spatial resolution to reveal Saturn's auroral oval. Saturn images include evidence for rapid auroral variations and polar UV-dark regions mostly inside the auroral ovals. Absorption bands of acetylene are clearly seen in the reflected sunlight spectrum. The auroral emission spectrum is similar to that of Jupiter, showing H2 band emission and H Lyman-alpha emission. Saturn's auroral, dayglow, and nightglow spectra show significant differences. Saturn's aurora is observed to vary in brightness by at least a factor of four. The brightest auroral emissions seen so far occurred after 2004 day 207 19:30 when Cassini CAPS and MAG recorded passage of a solar wind shock. The enhanced auroral brightness persisted for days, and is seen at both poles of Saturn. Cassini RPWS observed enhanced auroral kilometric emissions during several auroral brightening events seen by UVIS. A campaign of Hubble Space Telescope UV imaging with ACS (Advanced Camera for Surveys) of Saturn's dayside southern auroral zone took place on 2005 February 17. Cassini UVIS and VIMS observed Saturn's nightside northern aurora during this period. The UVIS long slit was aligned with lines of latitude on Saturn, providing information about intensity and spectral variations along the auroral oval. Cassini VIMS has now obtained an initial image and spectrum of Saturn's H3}+ auroral emissions. [less ▲]

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See detailObservations of serum trace elements in chronic lymphocytic leukemia.
Beguin, Yves ULg; Brasseur, Françoise ULg; Weber, Géraldine ULg et al

in Cancer (1987), 60(8), 1842-6

Serum trace elements (STE) were measured in 50 patients with chronic lymphocytic leukemia (CLL) and 100 normal subjects. Copper was higher in patients than in controls (1.50 +/- 0.06 versus 1.10 +/- 0.02 ... [more ▼]

Serum trace elements (STE) were measured in 50 patients with chronic lymphocytic leukemia (CLL) and 100 normal subjects. Copper was higher in patients than in controls (1.50 +/- 0.06 versus 1.10 +/- 0.02 micrograms/ml, P less than 0.001), increased steadily from Stage 0 to Stage 4 (P = 0.002), and correlated with the lymphocyte count and serum lactate dehydrogenase (P less than 0.01) but not with acute phase reactants. Zinc was lower in patients than in controls (0.94 +/- 0.03 versus 1.10 +/- 0.02 micrograms/ml, P less than 0.001). Zinc (NS), selenium (P = 0.039), and calcium (P = 0.033), were decreased in Stages 3-4 as compared to Stages 0-2. The copper-to-zinc ratio (CZR) increased continuously from Stage 0 to Stage 4 (P less than 0.001). Discriminant analysis between two groups, Stage 0-2 and Stage 3-4, based on serum copper, zinc, calcium, and protein levels, allowed for a correct classification of 94% of the patients. Moreover, the clinical staging of the remaining 6% was modified retrospectively according to the results of discriminant analysis. It was concluded that (1) serum copper and CZR are useful indices of the extent of disease, (2) they are independent of a nonspecific acute phase reaction, (3) STE determination could be helpful in the staging of a limited number of CLL patients, and (4) zinc deficiency could contribute to immune dysfunction in CLL. [less ▲]

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See detailObservations of short time scale variability of the Jovian UV aurora and simulation of morphological patterns
Gérard, Jean-Claude ULg; Grodent, Denis ULg; Dols, V. et al

in Bulletin of the American Astronomical Society (1997, July 01)

A database of far ultraviolet auroral images collected with the Faint Object Camera and Wide Field Planetary Camera (WFPC2) on board the Hubble Space Telescope has been constructed over the last five ... [more ▼]

A database of far ultraviolet auroral images collected with the Faint Object Camera and Wide Field Planetary Camera (WFPC2) on board the Hubble Space Telescope has been constructed over the last five years. Some morphological features are recurrent but significant time variations are also observed. A set of WFPC2 images obtained in May 1997 shows that, within a relatively stable general morphology, variations occur inside the polar cap in 4 minutes or less, implying short timescale acceleration processes. A model simulating Earth view of auroral arcs and diffuse emissions in the north polar region has been developed. Simple geometric cases are described to illustrate the dependence on the altitude, atmospheric scale height and central meridian planetary longitude of an idealized auroral morphology seen from Earth orbit. The numerical simulation makes it possible to assess the importance of limb brightening and the contribution from high altitude auroral emission located behind the planetary limb. As an application, four images obtained with WFPC2 are used to determine the characteristics of their auroral (discrete and diffuse) structures. The apparent brightness distribution along the arcs may only be reproduced if intrinsic longitudinal (or local time) variations are introduced, in addition to the path length effects of the viewing geometry. [less ▲]

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See detailObservations of significant flux closure by dual lobe reconnection
Imber, S. M.; Milan, S. E.; Hubert, Benoît ULg

in Annales Geophysicae (2007), 25(7), 1617-1627

We present an interval of dual lobe reconnection during which interplanetary magnetic field lines are captured by the magnetosphere by reconnecting at high latitudes in both the Northern and the Southern ... [more ▼]

We present an interval of dual lobe reconnection during which interplanetary magnetic field lines are captured by the magnetosphere by reconnecting at high latitudes in both the Northern and the Southern Hemispheres. This event was identified using measurements of the ionospheric convection flow and observations of the aurora using the Super-DARN radars and the IMAGE spacecraft. A cusp spot, characteristic of northward IMF, is clearly visible for a 30 min period enabling the ionospheric footprint of the Northern Hemisphere merging gap to be accurately determined. During the interval a strong burst of sunward flow across the dayside open/closed field line boundary (OCB) is observed, which we interpret as the reconfiguration of the magnetosphere following a burst of reconnection. Noon-midnight and dawn-dusk keograms of the aurora show that the polar cap shrinks during the interval indicating that a large amount of flux was closed by the reconnection. Using the SuperDARN potential maps it is possible to calculate that the amount of flux closed during the interval is 0.13 GWb which represents approximately 10% of the pre-existing polar cap. The number of ions captured by the burst of dual lobe reconnection was calculated to be similar to 2.2x10(31), more than sufficient to populate a cold, dense plasma sheet. That a dense plasma sheet was not subsequently observed is discussed in terms of subsequent changes in the IMF. [less ▲]

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See detailObservations of southern nebulae
Danks, A. C.; Houziaux, Léo ULg; Manfroid, Jean ULg

in Astrophysics & Space Science (1976), 39

Spectroscopic observations of 10 H II regions in the southern hemisphere are presented. The observations cover the spectral region 3600-8000 A.

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