Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
See detailNear real time assessment of the Space Weather effect on navigation based on the DGPS technique
Lejeune, Sandrine; Warnant, René ULg; Barré, Aline et al

Conference (2005)

Detailed reference viewed: 9 (0 ULg)
See detailNear real-time assessment of the ionospheric effect on navigation based on DGPS corrections
Lejeune, Sandrine; Warnant, René ULg; Barré, Aline et al

in Proceedings of Beacon Satellite Symposium 2004 (2005)

Detailed reference viewed: 12 (1 ULg)
See detailNear real-time evaluation of the EGNOS ionospheric correction at mid-latitude
Bavier, Michaël; Warnant, René ULg; Barré, Aline et al

in Proceedings of Beacon Satellite Symposium 2004 (2005)

Detailed reference viewed: 20 (1 ULg)
See detailNear real-time validation of GPS-TEC using ionosonde TEC at Dourbes
Warnant, René ULg; Nebdi, Hamid; Pottiaux, Eric

Report (2003)

Detailed reference viewed: 21 (2 ULg)
Full Text
Peer Reviewed
See detailNear- and mid-infrared colours of star-forming galaxies in European Large Area ISO Survey fields
Vaisanen, Petri; Morel, Thierry ULg; Rowan-Robinson, M. et al

in Monthly Notices of the Royal Astronomical Society (2002), 337

We present J- and K-band near-infrared (near-IR) photometry of a sample of mid-infrared (mid-IR) sources detected by the Infrared Space Observatory (ISO) as part of the European Large Area ISO Survey ... [more ▼]

We present J- and K-band near-infrared (near-IR) photometry of a sample of mid-infrared (mid-IR) sources detected by the Infrared Space Observatory (ISO) as part of the European Large Area ISO Survey (ELAIS) and study their classification and star-forming properties. We have used the Preliminary ELAIS Catalogue for the 6.7-μm (LW2) and 15-μm (LW3) fluxes. All of the high-reliability LW2 sources and 80 per cent of the LW3 sources are identified in the near-IR survey reaching K~ 17.5 mag. The near-IR/mid-IR flux ratios can effectively be used to separate stars from galaxies in mid-IR surveys. The stars detected in our survey region are used to derive a new accurate calibration for the ELAIS ISOCAM data in both the LW2 and LW3 filters. We show that near- to mid-IR colour-colour diagrams can be used to classify galaxies further, as well as to study star formation. The ELAIS ISOCAM survey is found mostly to detect strongly star-forming late-type galaxies, possibly starburst-powered galaxies, and it also picks out obscured active galactic nuclei. The ELAIS galaxies yield an average mid-IR flux ratio LW2/LW3 = 0.67 +/- 0.27. We discuss the f[SUB]ν[/SUB](6.7 μ m)/f[SUB]ν[/SUB](15 μ m) ratio as a star formation tracer using ISO and IRAS data of a local comparison sample. We find that the f[SUB]ν[/SUB](2.2 μ m)/f[SUB]ν[/SUB](15 μ m) ratio is also a good indicator of activity level in galaxies and conclude that the drop in the f[SUB]ν[/SUB](6.7 μ m)/f[SUB]ν[/SUB](15 μ m) ratio seen in strongly star-forming galaxies is a result of both an increase of 15-μm emission and an apparent depletion of 6.7-μm emission. Near-IR together with the mid-IR data make it possible to estimate the relative amount of interstellar matter in the galaxies. [less ▲]

Detailed reference viewed: 13 (1 ULg)
Peer Reviewed
See detailNear-Death Experiences : Real or imagined memories?
Thonnard, Marie ULg; Laureys, Steven ULg; Brédart, Serge ULg et al

Poster (2010, September)

Detailed reference viewed: 69 (9 ULg)
Peer Reviewed
See detailNear-death experiences: real or imagined?
Thonnard, Marie ULg; Laureys, Steven ULg; Brédart, Serge ULg et al

Conference (2010, June)

Detailed reference viewed: 42 (4 ULg)
Full Text
Peer Reviewed
See detailNear-field coupling of wireless devices and long communications cables
Christopoulos, Christos; Zhang, Yinghong ULg; Paul, J. et al

in IET Science, Measurement & Technology (2008), 2(1), 18-24

A comprehensive investigation of the coupling between mobile devices and communication/control cables in several environments is described here. Both experimental and numerical results are shown and ... [more ▼]

A comprehensive investigation of the coupling between mobile devices and communication/control cables in several environments is described here. Both experimental and numerical results are shown and compared using a number of different methods in different laboratories. Results indicate a good level of agreement between the different approaches thus giving confidence that predictive studies based on simulation can give a good quantitative assessment of coupling. Moreover, the studies show that varying the configuration of the coupled systems does not significantly affects the maximum coupling thus making it possible to obtain a reasonable worst case estimate of coupling from a small number of generic studies. [less ▲]

Detailed reference viewed: 66 (6 ULg)
Full Text
Peer Reviewed
See detailNear-infrared [Fe II] emission from supernova remnants and the supernova rate of starburst galaxies
Morel, Thierry ULg; Doyon, R.; St-Louis, N.

in Monthly Notices of the Royal Astronomical Society (2002), 329

In an effort better to calibrate the supernova rate of starburst galaxies as determined from near-infrared [FeII] features, we report on a [FeII] λ1.644μm line-imaging survey of a sample of 42 optically ... [more ▼]

In an effort better to calibrate the supernova rate of starburst galaxies as determined from near-infrared [FeII] features, we report on a [FeII] λ1.644μm line-imaging survey of a sample of 42 optically selected supernova remnants (SNRs) in M33. A wide range of [FeII] luminosities are observed within our sample (from less than 6 to 695L[SUB]solar[/SUB]). Our data suggest that the bright [FeII] SNRs are entering the radiative phase and that the density of the local interstellar medium (ISM) largely controls the amount of [FeII] emission. We derive the following relation between the [FeII] λ1.644μm line luminosity of radiative SNRs and the electronic density of the post-shock gas, n[SUB]e[/SUB]: L[SUB][FeII][/SUB] (L[SUB]solar[/SUB])~1.1n[SUB]e[/SUB] (cm[SUP]-3[/SUP]). We also find a correlation in our data between L[SUB][FeII][/SUB] and the metallicity of the shock-heated gas, but the physical interpretation of this result remains inconclusive, as our data also show a correlation between the metallicity and n[SUB]e[/SUB]. The dramatically higher level of [FeII] emission from SNRs in the central regions of starburst galaxies is most likely due to their dense environments, although metallicity effects might also be important. The typical [FeII]-emitting lifetime of a SNR in the central regions of starburst galaxies is found to be of the order of 10[SUP]4[/SUP]yr. On the basis of these results, we provide a new empirical relation allowing the determination of the current supernova rate of starburst galaxies from their integrated near-infrared [FeII] luminosity. [less ▲]

Detailed reference viewed: 16 (1 ULg)
Full Text
Peer Reviewed
See detailNear-infrared identification of the counterpart to X1908+075: a new OB-supergiant X-ray binary
Morel, Thierry ULg; Grosdidier, Y.

in Monthly Notices of the Royal Astronomical Society (2005), 356

We report the near-infrared (near-IR) identification of the likely counterpart to X1908+075, a highly absorbed Galactic X-ray source recently suspected to belong to the rare class of OB supergiant-neutron ... [more ▼]

We report the near-infrared (near-IR) identification of the likely counterpart to X1908+075, a highly absorbed Galactic X-ray source recently suspected to belong to the rare class of OB supergiant-neutron star binary systems. Our JHK[SUB]s[/SUB]-band imaging of the field reveals the existence within the X-ray error boxes of a near-IR source consistent with an early-type star lying at d~ 7 kpc and suffering A[SUB]V[/SUB]~ 16 mag of extinction, the latter value being in good agreement with the hydrogen column density derived from modelling of the X-ray spectrum. Our follow-up, near-IR spectroscopic observations confirm the nature of this candidate and lead to a late O-type supergiant classification, thereby supporting the identification of a new Galactic OB-supergiant X-ray binary. [less ▲]

Detailed reference viewed: 4 (1 ULg)
Full Text
Peer Reviewed
See detailA near-infrared interferometric survey of debris disc stars. II. CHARA/FLUOR observations of six early-type dwarfs
Absil, Olivier ULg; di Folco, E.; Mérand, A. et al

in Astronomy and Astrophysics (2008), 487

Aims. We aim at directly detecting the presence of optically thin circumstellar dust emission within the terrestrial planetary zone around main sequence stars known to harbour cold debris discs. The ... [more ▼]

Aims. We aim at directly detecting the presence of optically thin circumstellar dust emission within the terrestrial planetary zone around main sequence stars known to harbour cold debris discs. The present study focuses on a sample of six bright A- and early F-type stars. Methods: High-precision interferometric observations have been obtained in the near-infrared K band with the FLUOR instrument installed on the CHARA Array. The measured squared visibilities are compared to the expected visibility of the stellar photospheres based on theoretical photospheric models taking into account rotational distortion. We search for potential visibility reduction at short baselines, a direct piece of evidence for resolved circumstellar emission. Results: Our observations bring to light the presence of resolved circumstellar emission around one of the six target stars (zeta Aql) at the 5sigma level. The morphology of the emission source cannot be directly constrained because of the sparse spatial frequency sampling of our interferometric data. Using complementary adaptive optics observations and radial velocity measurements, we find that the presence of a low-mass companion is a likely origin for the excess emission. The potential companion is characterised by a K-band contrast of four magnitudes. It has a most probable mass of about 0.6~Msun and is expected to orbit between about 5.5 AU and 8 AU from its host star assuming a purely circular orbit. Nevertheless, by adjusting a physical debris disc model to the observed Spectral Energy Distribution of the zeta Aql system, we also show that the presence of hot dust within 10 AU from zeta Aql, producing a total thermal emission equal to 1.69 ± 0.31% of the photospheric flux in the K band, is another viable explanation for the observed near-infrared excess. Our re-interpretation of archival near- to far-infrared photometric measurements shows however that cold dust is not present around zeta Aql at the sensitivity limit of the IRS and MIPS instruments onboard Spitzer, and urges us to remove zeta Aql from the category of bona fide debris disc stars. Conclusions: The hot debris disc around Vega (Absil et al. 2006) currently remains our only secure resolved detection within the context of this survey, with six genuine early-type debris disc stars observed so far. Further observations will be needed to assess whether zeta Aql also belongs to this hot debris disc category. Partly based on observations collected at the European Southern Observatory, La Silla, Chile, under program IDs 073.C-0733, 077.C-0295 and 080.C-0712. [less ▲]

Detailed reference viewed: 29 (4 ULg)
Full Text
Peer Reviewed
See detailA near-infrared interferometric survey of debris disc stars. III. First statistics based on 42 stars observed with CHARA/FLUOR
Absil, Olivier ULg; Defrère, Denis; Coudé du Foresto, Vincent et al

in Astronomy and Astrophysics (2013), 555

Context. Dust is expected to be ubiquitous in extrasolar planetary systems due to the dynamical activity of minor bodies. Inner dust populations are, however, still poorly known due to the high contrast ... [more ▼]

Context. Dust is expected to be ubiquitous in extrasolar planetary systems due to the dynamical activity of minor bodies. Inner dust populations are, however, still poorly known due to the high contrast and small angular separation with respect to their host star. Yet, a proper characterisation of exozodiacal dust is mandatory for the design of future Earth-like planet imaging missions. Aims. We aim to determine the level of near-infrared exozodiacal dust emission around a sample of 42 nearby main sequence stars with spectral types ranging from A to K, and to investigate its correlation with various stellar parameters and with the presence of cold dust belts. Methods. We use high-precision K-band visibilities obtained with the FLUOR interferometer on the shortest baseline of the CHARA array. The calibrated visibilities are compared with the expected visibility of the stellar photosphere to assess the presence of an additional, fully resolved circumstellar emission source. Results. Near-infrared circumstellar emission amounting to about 1% of the stellar flux is detected around 13 of our 42 target stars. Follow-up observations showed that one of them (eps Cep) is associated with a stellar companion, while another one was detected around what turned out to be a giant star (kap CrB). The remaining 11 excesses found around single main sequence stars are most probably due to the presence of hot circumstellar dust, yielding an overall occurrence rate of 28+8-6% for our (biased) sample. We show that the occurrence rate of bright exozodiacal discs correlates with spectral type, K-band excesses being more frequent around A-type stars. It also correlates with the presence of detectable far-infrared excess emission in the case of solar-type stars. Conclusions. This study provides new insights regarding the phenomenon of bright exozodiacal disc, showing that hot dust populations are probably linked to outer dust reservoirs in the case of solar-type stars. In the case of A-type stars, no clear conclusion can be made regarding the origin of the detected near-infrared excesses. [less ▲]

Detailed reference viewed: 51 (13 ULg)
Full Text
Peer Reviewed
See detailA near-infrared interferometric survey of debris disk stars. I. Probing the hot dust content around eps Eridani and tau Ceti with CHARA/FLUOR
Di Folco, Emmanuel; Absil, Olivier ULg; Augereau, J.-C. et al

in Astronomy and Astrophysics (2007), 475

Context: The quest for hot dust in the central region of debris disks requires high resolution and high dynamic range imaging. Near-infrared interferometry is a powerful means to directly detect faint ... [more ▼]

Context: The quest for hot dust in the central region of debris disks requires high resolution and high dynamic range imaging. Near-infrared interferometry is a powerful means to directly detect faint emission from hot grains. Aims: We probed the first 3 AU around tau Ceti and eps Eridani with the CHARA array (Mt Wilson, USA) in order to gauge the 2 mum excess flux emanating from possible hot dust grains in the debris disks and to also resolve the stellar photospheres. Methods: High precision visibility amplitude measurements were performed with the FLUOR single mode fiber instrument and telescope pairs on baselines ranging from 22 to 241 m of projected length. The short baseline observations allow us to disentangle the contribution of an extended structure from the photospheric emission, while the long baselines constrain the stellar diameter. Results: We have detected a resolved emission around tau Cet, corresponding to a spatially integrated, fractional excess flux of 0.98±0.21 × 10[SUP]-2[/SUP] with respect to the photospheric flux in the K'-band. Around eps Eri, our measurements can exclude a fractional excess of greater than 0.6× 10[SUP]-2[/SUP] (3sigma). We interpret the photometric excess around tau Cet as a possible signature of hot grains in the inner debris disk and demonstrate that a faint, physical or background, companion can be safely excluded. In addition, we measured both stellar angular diameters with an unprecedented accuracy: Theta_LD(tau Cet)= 2.015 ± 0.011 mas and Theta_LD(eps Eri)=2.126 ± 0.014 mas. [less ▲]

Detailed reference viewed: 41 (1 ULg)
Full Text
Peer Reviewed
See detailNear-infrared spectroscopy for analysis of oil content and fatty acid profile in Jatropha curcas L. flour
Terren, Marieke ULg; Lecler, B.; Baeten, V. et al

Poster (2013)

Detailed reference viewed: 24 (4 ULg)
Full Text
Peer Reviewed
See detailNear-intrared observations of the HE 0450-2958 system: discovery of a second active galactic nucleus?
Letawe, Géraldine ULg; Magain, Pierre ULg; Chantry, Virginie ULg et al

in Monthly Notices of the Royal Astronomical Society (2009), 396(1), 78-84

The quasi-stellar object (QSO) HE 0450−2958 was brought to the front scene by the non-detection of its host galaxy and strong upper limits on the latter's luminosity. The QSO is also a powerful infrared ... [more ▼]

The quasi-stellar object (QSO) HE 0450−2958 was brought to the front scene by the non-detection of its host galaxy and strong upper limits on the latter's luminosity. The QSO is also a powerful infrared emitter, in gravitational interaction with a strongly distorted ultraluminous infrared companion galaxy. We investigate the properties of the companion galaxy, through new near- and mid-infrared observations of the system obtained with Near Infrared Camera and Multi-Object Spectrometer (NICMOS) onboard Hubble Space Telescope, Infrared Spectrometer and Array Camera (ISAAC) and Very Large Telescope Imager and Spectrometer in the Infrared (VISIR) on the European Southern Observatory Very Large Telescope. The companion galaxy is found to harbour a point source revealed only in the infrared, in what appears as a hole or dark patch in the optical images. Various hypotheses on the nature of this point source are analysed and it is found that the only plausible one is that it is a strongly reddened active galactic nucleus hidden behind a thick dust cloud. The hypothesis that the QSO supermassive black hole might have been ejected from the companion galaxy in the course of a galactic collision involving three-body black holes interaction is also reviewed, on the basis of this new insight on a definitely complex system. [less ▲]

Detailed reference viewed: 43 (14 ULg)
Full Text
Peer Reviewed
See detailA Near-IR [Fe II] line imaging survey of supernova remnants in M33
Morel, Thierry ULg; Doyon, R.; St-Louis, N.

in Proceedings 232. WE-Heraeus Seminar (2000, December 01)

We report on the first near-IR [Fe II] line imaging survey of extragalactic SNRs. Observations of a sample of 42 objects drawn from an optically-selected catalogue of SNRs in M33 provide evidence for a ... [more ▼]

We report on the first near-IR [Fe II] line imaging survey of extragalactic SNRs. Observations of a sample of 42 objects drawn from an optically-selected catalogue of SNRs in M33 provide evidence for a wide range in the [Fe II]λ 1.644 micron luminosities. This can be understood as being primarily due to variations in the chemical abundances and density of the local ISM, although shock conditions may also play a significant role. We briefly discuss how these results may be used to better calibrate the supernova rate of star-forming galaxies. [less ▲]

Detailed reference viewed: 5 (1 ULg)