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See detailCPD-41° 7742: an unusual wind interaction
Sana, H.; Gosset, Eric ULiege; Rauw, Grégor ULiege et al

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

We summarize the results of a multiwavelength observing campaign on the massive eclipsing binary CPD-41° 7742, another remarkable object in the young open cluster NGC 6231. Our campaign relies on high ... [more ▼]

We summarize the results of a multiwavelength observing campaign on the massive eclipsing binary CPD-41° 7742, another remarkable object in the young open cluster NGC 6231. Our campaign relies on high resolution echelle spectroscopy, narrow-band optical photometry, and XMM-Newton X-ray observations. Combined with the spectroscopic analysis, the light curve analysis provides a direct measurement of the masses and sizes of the system components. However, the most outstanding results come from the XMM observations. Our 180 ks campaign towards NGC 6231, and CPD-41° 7742, provides an unprecedented phase coverage of such a close early-type binary. The EPIC-MOS light curves almost fully cover the 2.4 day period of the system and the brightness of the object is sufficient to yield a time resolution as tight as 1 ks. The X-ray flux presents clear variations along the orbit, that we interpret as the signature of an unusual wind interaction. We indeed expect that, in this O+B system, the dominant primary wind crashes into the secondary surface, leading to a wind-photosphere interaction. As a strong support to our interpretation, we provide a geometrical model that associates an extra X-ray emission to the secondary inner surface. Though quite simple, the present model matches the main features of the X-ray light curve. [less ▲]

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See detailPreliminary results of an observational campaign aiming at the study of the binary system LSS3074
Gosset, Eric ULiege; Rauw, Grégor ULiege; Manfroid, Jean ULiege et al

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

We present preliminary results of an observational campaign aiming at the study of the binary system LSS3074. A new lightcurve clearly indicates that the system is in contact. Recent spectroscopy broadly ... [more ▼]

We present preliminary results of an observational campaign aiming at the study of the binary system LSS3074. A new lightcurve clearly indicates that the system is in contact. Recent spectroscopy broadly confirms the previous results and the rather low masses of both components (O4f[SUP]+[/SUP] and O6-7:(f):). We further analyse an XMM-Newton observation of the object that indicates a rather hard X-ray spectrum. This is partly due to the high interstellar extinction towards the object but also to the high plasma temperature (kT Ë 1.2-1.3 keV). [less ▲]

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See detailAre WC9 Wolf-Rayet stars in colliding-wind binaries?
Williams, P. M.; van der Hucht, K. A.; Rauw, Grégor ULiege

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

We present results from a spectroscopic search for massive companions to dust-making Galactic WC9 stars as a step to testing the paradigm that dust formation in these systems requires colliding winds to ... [more ▼]

We present results from a spectroscopic search for massive companions to dust-making Galactic WC9 stars as a step to testing the paradigm that dust formation in these systems requires colliding winds to produce over densities. We find evidence for OB companions to the WC9 stars WR 59 and WR 65, but not WR 121 or WR 117. We identify lines of N III-V and possibly N II in the spectrum of WR 88, one of the few Galactic WC9 stars which do not make circumstellar dust, and suggest that WR 88 is a transitional WN--WC9 object and less evolved than the other WC9 stars. On the other hand, the possible identification of a strong emission line at 4176 in the spectrum of WR 117 with Ne I suggests that this star is more evolved than other WC9 stars studied. [less ▲]

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See detailThe XMM-Newton view of Plaskett's star and its surroundings
Linder, N.; Rauw, Grégor ULiege

in Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

XMM data of Plaskett's star (HD 47129) are used in order to analyse its X-ray spectrum and variability and hence to derive further constraints on the wind interaction in this early-type binary (O6 I + O7 ... [more ▼]

XMM data of Plaskett's star (HD 47129) are used in order to analyse its X-ray spectrum and variability and hence to derive further constraints on the wind interaction in this early-type binary (O6 I + O7.5 I) system. Combining the information provided by the EPIC and RGS instruments, we find that the X-ray spectrum of Plaskett's star is dominated by thermal plasma at lower energies, whereas the higher energy part (> 3 keV) could probably best be represented by a featureless power law component since we do not detect a significant Fe-K line. Our tests also suggest that an overabundance in nitrogen by a factor Ë 6 might be indicated to best represent the RGS spectrum. On the other hand, 71 X-ray sources have been detected in Plaskett's star field of view and most of them have counterparts in near-IR colours that are consistent with slightly reddened main-sequence objects. Actually, a sizeable fraction of the X-ray sources in the EPIC images could be either foreground or background sources with no direct connection to HD 47129. [less ▲]

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See detailNon-LTE effects on H-3(+) emission in the jovian upper atmosphere
Melin, Henrik; Miller, Steve; Stallard, Tom et al

in Icarus: International Journal of Solar System Studies (2005), 178(1), 97-103

Calculations of column intensities are performed for a number of infrared transitions of the H-3(+) molecular ion, using a model atmosphere recently produced by Grodent et al. [2001. A self-consistent ... [more ▼]

Calculations of column intensities are performed for a number of infrared transitions of the H-3(+) molecular ion, using a model atmosphere recently produced by Grodent et al. [2001. A self-consistent model of the jovian auroral thermal structure. J. Geophys. Res. 106, 12933-12952]. The line intensities integrated along the line of sight through the model atmosphere are first computed assuming that all of the emitting energy levels are in local thermodynamic equilibrium (LTE). These results are compared with those derived from a detailed balance calculation using a method recently proposed by Oka and Epp [2004. Non-thermal rotational distribution of H-3(+). Astrophys. J. In press]. It is shown that the population of excited vibrational levels starts to depart from that derived from LTE at attitudes higher than 500 km (above the jovian cloud tops). This effect has been noted previously by Kim et it. [1992. Densities and vibrational distribution of H-3(+) in the jovian auroral atmosphere. J. Geophys. Res. 97, 6093-6101]. By 2000 km, all of the excited vibrational levels are Populated at less than 10% of the expected LTE value. This has important implications for the jovian upper atmosphere. In particular, the H-3(+) cooling effect will be greatly reduced high in the atmosphere. Modelled LTE line emission is greater than that derived from non-LTE modelling. Comparison of the non-LTE modelling with recent spectral measurements of the jovian auroral/polar regions in the L- and K-infrared windows shows that the Grodent et al. [2001. A self-consistent model of the jovian auroral thermal structure. J. Geophys. Res. 106, 12933-12952] profile overestimates the measured line intensity by similar to 3. Allowing for this, the non-LTE modelling shows that the column densities derived from (quasi-)LTE treatment of the measured line intensities may underestimate the real H-3(+) abundance by a factor of between 6 and 200. This means that attempts to derive important ionospheric properties, such as conductivity and related energy inputs due to magnetosphere-ionosphere coupling, front observed spectra will need to take this into account, if they are not to be seriously in error. (c) 2005 Elsevier Inc. All rights reserved. [less ▲]

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See detailRadiative parameters for some transitions in the spectrum of Ag-II
Campos, J.; Ortiz, M.; Mayo, R. et al

in Monthly Notices of the Royal Astronomical Society (2005), 363(3), 905-910

Radiative parameters for transitions depopulating the levels belonging to the 4d(8)5s(2), 4d(9)6s and 4d(9)5d configurations of Ag II have been obtained from a combination of theoretical lifetimes and ... [more ▼]

Radiative parameters for transitions depopulating the levels belonging to the 4d(8)5s(2), 4d(9)6s and 4d(9)5d configurations of Ag II have been obtained from a combination of theoretical lifetimes and experimental branching fractions. On the experimental side, a laser-produced plasma was used as a source of Ag+ ions. The light emitted by the plasma was analysed by a grating monochromator coupled with a time-resolved optical multichannel analyser system. Spectral response calibration of the experimental system was performed using a deuterium lamp in the wavelength range from 200 to 400 nm, and a standard tungsten lamp in the range from 350 to 600 nm. The transition probabilities were obtained from measured branching ratios and theoretical radiative lifetimes of the corresponding states calculated with a relativistic Hartree-Fock approach including core-polarization effects and configuration interaction in an extensive way. Theoretical and experimental data have been compared and the new data have also been compared with the few previous results available in the literature. [less ▲]

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See detailA spectroscopic investigation of the young open cluster IC 1805
De Becker, Michaël ULiege; Rauw, Grégor ULiege

in Rauw, Grégor; Nazé, Yaël; Blomme, R. (Eds.) et al Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

We present the main results of a spectroscopic campaign devoted to the O-type stars in the young open cluster IC 1805. This study aims at the investigation of the multiplicity and the line profile ... [more ▼]

We present the main results of a spectroscopic campaign devoted to the O-type stars in the young open cluster IC 1805. This study aims at the investigation of the multiplicity and the line profile variability of its brightest massive members. We present new results concerning the line profile variability of He II 4686 and H-beta for HD 15570 and HD 15629. For these two stars, our radial velocity analysis does not reveal any variations compatible with a binary motion. We also significantly improve the orbital parameters of the long period binary HD 15558. For this latter system, we present for the first time evidence for the detection of the secondary, leading to spectral types of O5.5 and O7 respectively for the two components. [less ▲]

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See detailSignature of Saturn's auroral cusp: Simultaneous Hubble Space Telescope FUV observations and upstream solar wind monitoring
Gérard, Jean-Claude ULiege; Bunce, Emma J; Grodent, Denis ULiege et al

in Journal of Geophysical Research. Space Physics (2005), 110

Model simulations by Bunce et al. (2005a) have shown that direct precipitation of electrons in Saturn's dayside cusp regions is not capable of producing significant FUV aurora. Instead, they suggested the ... [more ▼]

Model simulations by Bunce et al. (2005a) have shown that direct precipitation of electrons in Saturn's dayside cusp regions is not capable of producing significant FUV aurora. Instead, they suggested the possibility that the FUV bright emissions sometimes observed near noon are associated with reconnection occurring at the dayside magnetopause, possibly pulsed, analogous to flux transfer events seen at the Earth. Pulsed reconnection at the low-latitude dayside magnetopause when the IMF is directed northward (antiparallel to Saturn's magnetic field lines) is expected to give rise to pulsed twin-vortical flows in the magnetosphere and hence to bipolar field-aligned currents centered in the vortical flows closing in ionospheric Pedersen current. In the case of southward IMF and high-latitude lobe reconnection the model predicts that the vortical flows are displaced poleward of the open-closed field line boundary with reversed field-aligned currents compared with the former case. During January 2004, a unique campaign took place during which magnetic field and plasma instruments on board the Cassini-Huygens spacecraft measured the in situ solar wind and embedded interplanetary magnetic field while the Hubble Space Telescope simultaneously observed the far ultraviolet aurora in Saturn's southern hemisphere. The IMF was highly structured during this interval. The electric potential at Cassini is estimated from solar wind magnetic field and velocity measurements for the case of low-latitude or lobe reconnection. We show that a dayside FUV signature of intense electron precipitation is found poleward of or along the main oval during a period of minor compression period when the dayside reconnection voltage is estimated to be ~30-100 kV. Overall, we find that the conceptual model of Bunce et al. (2005a) provides a good estimate of the UV brightness and power for the case of northward IMF but somewhat underestimates the power for the southward IMF case, except if the speed of the vortical flow is larger than its value in the nominal model. [less ▲]

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See detailOptimization of BaZrO3 sintering by control of the initial powder size distribution; a factorial design statistical analysis
Guillaume, Bernard ULiege; Boschini, Frédéric ULiege; Garcia-Cano, I. et al

in Journal of the European Ceramic Society (2005), 25(16), 3593-3604

A factorial design statistical analysis has been conducted in order to obtain the optimum conditions in the solid state sintering process of barium zirconate bulk materials, optimum with respect to ... [more ▼]

A factorial design statistical analysis has been conducted in order to obtain the optimum conditions in the solid state sintering process of barium zirconate bulk materials, optimum with respect to density, closed and open porosities. The optimized heat treatment permits to sinter a 99% dense barium zirconate sample at 1650 degrees C during only 2 h. When the temperature is higher than 1650 degrees C or when the heating time is longer than 2 h, a decrease in density is observed. (c) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailCurrent status of hematopoietic stem cell transplantation after nonmyeloablative conditioning
Baron, Frédéric ULiege; Sandmaier, B. M.

in Current Opinion in Hematology (2005), 12(6), 435-443

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See detailLes obligations juridiques de cohérence du droit ou comment le droit se protège contre lui-même
Delnoy, Michel ULiege

in Biquet, Christine; Deliège, Alain; Lecocq, Pascale (Eds.) et al Liber Amicorum Paul Delnoy (2005)

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See detailDelayed chlorophyll accumulation and pigment photodestruction in the epicotyls of dark-grown pea (Pisum sativum)
Boddi, B.; Loudeche, R.; Franck, Fabrice ULiege

in Physiologia Plantarum (2005), 125(3), 365-372

A comparison was performed of the tetrapyrrole transformations that occur upon irradiation of epicotyl or leaves of dark-grown Pisum sativum L. (var. Zsuzsi, Hungary). High performance liquid ... [more ▼]

A comparison was performed of the tetrapyrrole transformations that occur upon irradiation of epicotyl or leaves of dark-grown Pisum sativum L. (var. Zsuzsi, Hungary). High performance liquid chromatography analysis after continuous or flash-irradiation showed that the biosynthetic pathway from protochlorophyllide (Pchlide) to chlorophyll (Chl) a was markedly slowed down at the step of the reduction of geranylgeranyl(gg)-Chl to dihydrogeranylgeranyl (dhgg)-Chl in epicotyls, whereas phytyl-Chl was synthesized in leaves subjected to the same light treatments. Quantitative pigment analysis during continuous irradiations of different intensities also showed that significant Pchlide photodestruction occurred in epicotyls even under weak light. When both Pchlide and chlorophyllide and/or chlorophylls were present in epicotyls, Pchlide photodestruction was faster under 630-nm light than under 670-nm light, which indicates that this process is most efficiently promoted by Pchlide excitation. Pre-incubation of epicotyl segments with 10 mM ascorbate partly alleviated pigment photodestruction in white light. It is concluded that formation of photoactive Pchlide-Pchlide oxidoreductase complexes is important to prevent fast pigment photooxidation after Pchlide accumulation in the dark. [less ▲]

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See detailMassive Stars and High-Energy Emission in OB Associations
Rauw, Grégor ULiege; Nazé, Yaël ULiege; Blomme, Ronny et al

Book (2005)

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See detailImaging of liquid distribution in reactive distillation packings with a new high-energy x-ray tomograph
Toye, Dominique ULiege; Crine, Michel ULiege; Marchot, Pierre ULiege

in Measurement Science & Technology (2005), 16(11), 2213-2220

We describe a new, high-energy (420 kV), large-scale (0.45 m in diameter, 4 m in height) x-ray tomograph developed to investigate gas and liquid flow through fixed bed like absorption, distillation and ... [more ▼]

We describe a new, high-energy (420 kV), large-scale (0.45 m in diameter, 4 m in height) x-ray tomograph developed to investigate gas and liquid flow through fixed bed like absorption, distillation and reactive distillation columns. The first results obtained with this set-up on test objects (physical phantoms), such as a cylindrical container filled with water or a large diameter structured metallic packing, validate the technique as a quantitative tool for geometrical measurements. Very detailed two-dimensional (21)) and three-dimensional (3D) images of a 0.09 m diameter KATAPAK-SP 12, a reactive distillation packing, are presented. Quantitative information relative to liquid hold-up distribution may be obtained from tomographic imaging performed on an irrigated column packed with this element. [less ▲]

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See detailAffective valence and the self-reference effect: influence of retrieval conditions
D'Argembeau, Arnaud ULiege; Comblain, Christine; Van der Linden, Martial ULiege

in British Journal of Psychology (2005), 96(Pt 4), 457-466

Positive trait information is typically better recalled than negative trait information when encoded in reference to the self, but not when encoded in reference to someone else or when processed for ... [more ▼]

Positive trait information is typically better recalled than negative trait information when encoded in reference to the self, but not when encoded in reference to someone else or when processed for general meaning. This study examined whether this influence of affective meaning is modulated by retrieval conditions. Participants encoded positive and negative trait adjectives in reference to themselves or to a celebrity. They were then presented with either a free-recall task (Experiment 1) or a recognition memory task (Experiment 2). Positive adjectives were better recalled than negative adjectives, but only when they were encoded in reference to the self. In contrast, encoding condition and valence did not interact in the recognition memory task. Taken together, these findings suggest that the difference in memory between positive and negative self-referent information is due, at least in part, to a control exerted on memory retrieval. [less ▲]

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