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See detailDiscovery of a magnetic field in the rapidly rotating O-type secondary of the colliding-wind binary HD 47129 (Plaskett's star)
Grunhut, J. H.; Wade, G. A.; Leutenegger, M. et al

in Monthly Notices of the Royal Astronomical Society (2013), 428

We report the detection of a strong, organized magnetic field in the secondary component of the massive O8III/I+O7.5V/III double-lined spectroscopic binary system HD 47129 (Plaskett's star) in the context ... [more ▼]

We report the detection of a strong, organized magnetic field in the secondary component of the massive O8III/I+O7.5V/III double-lined spectroscopic binary system HD 47129 (Plaskett's star) in the context of the Magnetism in Massive Stars survey. Eight independent Stokes V observations were acquired using the Echelle SpectroPolarimetric Device for the Observations of Stars (ESPaDOnS) spectropolarimeter at the Canada-France-Hawaii Telescope and the Narval spectropolarimeter at the Télescope Bernard Lyot. Using least-squares deconvolution we obtain definite detections of signal in Stokes V in three observations. No significant signal is detected in the diagnostic null (N) spectra. The Zeeman signatures are broad and track the radial velocity of the secondary component; we therefore conclude that the rapidly rotating secondary component is the magnetized star. Correcting the polarized spectra for the line and continuum of the (sharp-lined) primary, we measured the longitudinal magnetic field from each observation. The longitudinal field of the secondary is variable and exhibits extreme values of -810 ± 150 and +680 ± 190 G, implying a minimum surface dipole polar strength of 2850 ± 500 G. In contrast, we derive an upper limit (3σ) to the primary's surface magnetic field of 230 G. The combination of a strong magnetic field and rapid rotation leads us to conclude that the secondary hosts a centrifugal magnetosphere fed through a magnetically confined wind. We revisit the properties of the optical line profiles and X-ray emission - previously interpreted as a consequence of colliding stellar winds - in this context. We conclude that HD 47129 represents a heretofore unique stellar system - a close, massive binary with a rapidly rotating, magnetized component - that will be a rich target for further study. [less ▲]

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See detailDiscovery of a Mississippian Reef in Turkey: The Upper Viséan Microbial-Sponge-Bryozoan-Coral Bioherm from Kongul Yayla (Taurides, S Turkey)
Denayer, Julien ULg; Aretz, Markus

in Turkish Journal of Earth Sciences (2012), 21(3), 375-389

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See detailDiscovery of a natural thiamine adenine nucleotide
Bettendorff, Lucien ULg; Wirtzfeld, Barbara; Makarchikov, Alexander F et al

in Nature Chemical Biology (2007), 3(4), 211-212

Several important cofactors are adenine nucleotides with a vitamin as the catalytic moiety. Here, we report the discovery of the first adenine nucleotide containing vitamin B1: adenosine thiamine ... [more ▼]

Several important cofactors are adenine nucleotides with a vitamin as the catalytic moiety. Here, we report the discovery of the first adenine nucleotide containing vitamin B1: adenosine thiamine triphosphate (AThTP, 1), or thiaminylated ATP. We discovered AThTP in Escherichia coli and found that it accumulates specifically in response to carbon starvation, thereby acting as a signal rather than a cofactor. We detected smaller amounts in yeast and in plant and animal tissues. [less ▲]

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See detailDiscovery of a New AM CVn System with the Kepler Satellite
Fontaine, G.; Brassard, P.; Green, E. M. et al

in Astrophysical Journal (2011), 726

We report the discovery of a new AM CVn system on the basis of broadband photometry obtained with the Kepler satellite supplemented by ground-based optical spectroscopy. Initially retained on Kepler ... [more ▼]

We report the discovery of a new AM CVn system on the basis of broadband photometry obtained with the Kepler satellite supplemented by ground-based optical spectroscopy. Initially retained on Kepler target lists as a potential compact pulsator, the blue object SDSS J190817.07+394036.4 (KIC 004547333) has turned out to be a high-state AM CVn star showing the He-dominated spectrum of its accretion disk significantly reddened by interstellar absorption. We constructed new grids of NLTE synthetic spectra for accretion disks in order to analyze our spectroscopic observations. From this analysis, we infer preliminary estimates of the rate of mass transfer, the inclination angle of the disk, and the distance to the system. The AM CVn nature of the system is also evident in the Kepler light curve, from which we extracted 11 secure periodicities. The luminosity variations are dominated by a basic periodicity of 938.507 s, likely to correspond to a superhump modulation. The light curve folded on the period of 938.507 s exhibits a pulse shape that is very similar to the superhump wavefront seen in AM CVn itself, which is a high-state system and the prototype of the class. Our Fourier analysis also suggests the likely presence of a quasi-periodic oscillation similar to those already observed in some high-state AM CVn systems. Furthermore, some very low-frequency, low-amplitude aperiodic photometric activity is likely present, which is in line with what is expected in accreting binary systems. Inspired by previous work, we further looked for and found some intriguing numerical relationships between the 11 secure detected frequencies, in the sense that we can account for all of them in terms of only three basic clocks. This is further evidence in favor of the AM CVn nature of the system. [less ▲]

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See detailDiscovery of a new spore assemblage in the Middle Devonian of Iberian Peninsula
Rial, Gonzalo; Cascales-Miñana, Borja ULg; Gozalo, Rodolfo et al

Conference (2015, July)

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See detailDiscovery of a Probable Physical Triple Quasar
Djorgovski, S. G.; Courbin, F.; Meylan, G. et al

in Astrophysical Journal Letters (2007), 662

We report the discovery of the first known probable case of a physical triple quasar. A previously known double system, QQ 1429-008 at z=2.076, is shown to contain a third, fainter QSO component at the ... [more ▼]

We report the discovery of the first known probable case of a physical triple quasar. A previously known double system, QQ 1429-008 at z=2.076, is shown to contain a third, fainter QSO component at the same redshift. Deep optical and IR imaging has failed to reveal a plausible lensing galaxy group or a cluster, and we are unable to construct any viable lensing model that could lead to the observed distribution of source positions and relative intensities of the three QSO image components. There are also hints of differences in the broadband spectral energy distributions of the different components, which are more naturally understood if they are physically distinct active galactic nuclei (AGNs). Therefore, we conclude that this system is most likely a physical triple quasar, the first such close QSO grouping known at any redshift. The projected component separations are ~30-50 kpc, typical of interacting galaxy systems. The existence of this highly unusual system supports the standard picture in which galaxy interactions lead to the onset of QSO activity. Based in part on the data obtained at the W. M. Keck Observatory, a scientific partnership among the California Institue of Technology, the University of California, and NASA, made possible by the generous financial support of the W. M. Keck Foundation; data obtained with VLT/Antu telescope at ESO-Paranal Observatory; and data obtained with the Hubble Space Telescope (HST), operated by NASA. This research also made use of data obtained from the US National Virtual Observatory, which is sponsored by the NSF. [less ▲]

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See detailDiscovery of a Probable Triple Quasar
Djorgovski, Stanislav G.; Courbin, F.; Meylan, G. et al

Conference (2007, January)

We report the discovery of a first known probable case of a physical triple quasar (not a gravitational lens). A previously known double system, QQ 1429-008 at z = 2.076, is shown to contain a third ... [more ▼]

We report the discovery of a first known probable case of a physical triple quasar (not a gravitational lens). A previously known double system, QQ 1429-008 at z = 2.076, is shown to contain a third, fainter QSO component at the same redshift within the measurement errors. Deep optical and IR imaging at the Keck and VLT telescopes has failed to reveal a plausible lensing galaxy group or a cluster, and moreover, we are unable to construct any viable lensing model which could lead to the observed distribution of source positions and relative intensities of the three QSO image components. Therefore, we conclude that this system is most likely a physical triple quasar, the first such close grouping known at any redshift. The projected component separations in the restframe are 30 50 kpc for the standard concordance cosmology, typical of interacting galaxy systems. The existence of this highly unusual system supports the standard picture in which galaxy interactions lead to the onset of QSO activity. [less ▲]

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See detailDiscovery of a quadruply imaged quasar surrounded by a ring
Sluse, Dominique ULg; Claeskens, Jean-François ULg; Surdej, Jean ULg et al

Conference (2003, January)

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See detailDiscovery of a quadruply lensed quasar - The 'clover leaf' H1413 + 117
Magain, Pierre ULg; Surdej, Jean ULg; Swings, J.-P. et al

in Nature (1988), 334

The authors report the discovery of a second gravitational lens system in the broad absorption line quasar H1413+117. Four images of comparable brightness are seen, separated by â ¡1 arcsec. The unique ... [more ▼]

The authors report the discovery of a second gravitational lens system in the broad absorption line quasar H1413+117. Four images of comparable brightness are seen, separated by â ¡1 arcsec. The unique configuration of the images, together with the fairly rare occurrence of this type of quasar, makes it incontrovertible that this is a lensed system, not a cluster of quasars. (See also 159.062). [less ▲]

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See detailDiscovery of a ring around Neptune
Haefner, R.; Manfroid, Jean ULg

Article for general public (1985)

The history of the discovery of Neptune and of the rings of Uranus is briefly reviewed, and the discovery of a ring around Neptune is described. The determination of some ring parameters is reported ... [more ▼]

The history of the discovery of Neptune and of the rings of Uranus is briefly reviewed, and the discovery of a ring around Neptune is described. The determination of some ring parameters is reported. Significant questions posed by the observations, e.g., why detections did not always occur when the ring zone passed in front of a star, are discussed. [less ▲]

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See detailDiscovery of a woman portrait behind La Violoniste by Kees Van Dongen through hyperspectral imaging
Herens, Elodie ULg; Defeyt, Catherine ULg; Walter, Philippe et al

in Heritage Science (in press)

Despite the fact that Kees Van Dongen was one of the most famous painter of the 20th century, only little information about his palette and his technique is available. To contribute to the ... [more ▼]

Despite the fact that Kees Van Dongen was one of the most famous painter of the 20th century, only little information about his palette and his technique is available. To contribute to the characterization of Van Dongen's painting materials, La Violoniste, painted by the artist around 1923, has been analyzed by using three complementary techniques: macro X-ray fluorescence (MA-XRF), Raman spectroscopy and hyperspectral imaging. The elemental repartition given by MA-XRF and the results obtained thanks to Raman spectroscopy help us to complete the identification of pigments contained in La Violoniste (lead white, iron oxides, cadmium yellow, vermilion, Prussian blue, titanium white, ultramarine, a chromium pigment and carbon black) while the results obtained via hyperspectral imaging reveal a hidden woman portrait. Besides the fact that Kees Van Dongen was particularly renowned for his female portraits, this hidden composition presents obvious stylistic similarities with the well-known portraits produced by the artist during his Parisian stay (starting from 1899). Thanks to Raman spectroscopy, visual examination and MA-XRF, we show that the original background contains ultramarine, the hidden portrait's clothes are probably made of the same colour as the present violinist's dress and her carnation contains zinc, contrary to the violinist's flesh which is mainly made of lead white. [less ▲]

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See detailDiscovery of Diffure Aurora on Mars
Stiepen, Arnaud ULg; Schneider; Jain et al

Conference (2015, September)

The Imaging Ultraviolet Spectrograph (IUVS, McClintock et al., 2014) onboard the MAVEN spacecraft has discovered diffuse aurora in Mars’ northern hemisphere spanning a wide range of geographic latitudes ... [more ▼]

The Imaging Ultraviolet Spectrograph (IUVS, McClintock et al., 2014) onboard the MAVEN spacecraft has discovered diffuse aurora in Mars’ northern hemisphere spanning a wide range of geographic latitudes and longitudes (Figure 1). This widespread aurora differs from the small auroral patches discovered by the SPICAM instrument onboard the Mars Express spacecraft (Bertaux et al., 2005; Leblanc et al., 2008; Gérard et al., submitted; Soret et al., submitted) restricted to regions of crustal magnetic fields in the southern hemisphere. Furthermore, the northern diffuse aurora appears to peak at altitudes below 100 km, while the crustal field aurora peaked around 120 km. [less ▲]

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See detailDiscovery of diffuse aurora on Mars
Schneider, N. M.; Deighan, J. I.; Jain, S. K. et al

in Science (2015), 350(6261),

Planetary auroras reveal the complex interplay between an atmosphere and the surrounding plasma environment.We report the discovery of low-Altitude, diffuse auroras spanning much of Mars' northern ... [more ▼]

Planetary auroras reveal the complex interplay between an atmosphere and the surrounding plasma environment.We report the discovery of low-Altitude, diffuse auroras spanning much of Mars' northern hemisphere, coincident with a solar energetic particle outburst. The Imaging Ultraviolet Spectrograph, a remote sensing instrument on the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, detected auroral emission in virtually all nightside observations for ~5 days, spanning nearly all geographic longitudes. Emission extended down to ~60 kilometer (km) altitude (1 microbar), deeper than confirmed at any other planet. Solar energetic particles were observed up to 200 kilo-electron volts; these particles are capable of penetrating down to the 60 km altitude. Given minimal magnetic fields over most of the planet, Mars is likely to exhibit auroras more globally than Earth. [less ▲]

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See detailDiscovery of Diffuse Aurora on Mars
Schneider, Nick; Stiepen, Arnaud ULg; Jain, S et al

Conference (2015)

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See detailDiscovery of English Grain Aphid (Hemiptera: Aphididae) Biotypes in China
Xu, Zhao-Huan; Chen, Julian; Cheng, Deng-Fa et al

in Journal of Economic Entomology (2011), 104(3), 1080-1086

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See detailDiscovery of Magnetic Fields in Slowly Pulsating B Stars
Hubrig, S.; Briquet, Maryline ULg; Schöller, M. et al

in Active OB-Stars: Laboratories for Stellar and Circumstellar Physics, ASP Conference Series, Vol. 361, Proceedings of the conference held 29 August - 2 September, 2005 at Hokkai-Gakuen University, Sapporo, Japan. (2007, March 01)

We present the first observations and conclusions of a magnetic survey with FORS 1 at the VLT of a sample of 25 Slowly Pulsating B stars. A clear mean longitudinal magnetic field of the order of a few ... [more ▼]

We present the first observations and conclusions of a magnetic survey with FORS 1 at the VLT of a sample of 25 Slowly Pulsating B stars. A clear mean longitudinal magnetic field of the order of a few hundred Gauss was detected in eleven SPBs. Among them several SPBs show a magnetic field that varies in time. It becomes clear that SPBs cannot be regarded anymore as non-magnetic stars. [less ▲]

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See detailDiscovery of magnetic fields in the βCephei star ξ1 CMa and in several slowly pulsating B stars*
Hubrig, S.; Briquet, Maryline ULg; Schöller, M. et al

in Monthly Notices of the Royal Astronomical Society (2006), 369

We present the results of a magnetic survey of a sample of eight βCephei stars and 26 slowly pulsating B (SPBs) stars with the FOcal Reducer low dispersion Spectrograph at the Very Large Telescope. A weak ... [more ▼]

We present the results of a magnetic survey of a sample of eight βCephei stars and 26 slowly pulsating B (SPBs) stars with the FOcal Reducer low dispersion Spectrograph at the Very Large Telescope. A weak mean longitudinal magnetic field of the order of a few hundred Gauss is detected in the βCephei star ξ[SUP]1[/SUP]CMa and in 13 SPB stars. The star ξ[SUP]1[/SUP]CMa becomes the third magnetic star among the βCephei stars. Before our study, the star ζCas was the only known magnetic SPB star. All magnetic SPB stars for which we gathered several magnetic field measurements show a field that varies in time. We do not find a relation between the evolution of the magnetic field with stellar age in our small sample. Our observations imply that βCephei and SPB stars can no longer be considered as classes of non-magnetic pulsators, but the effect of the fields on the oscillation properties remains to be studied. [less ▲]

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