References of "2011"
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See detailSolutions and periodicity of satellite relative motion under even zonal harmonics perturbations
Martinusi, Vladimir ULg; Gurfil, Pini

in Celestial Mechanics and Dynamical Astronomy (2011), 111

Finding relative satellite orbits that guarantee long-term bounded relative motion is important for cluster flight, wherein a group of satellites remain within bounded distances while applying very few ... [more ▼]

Finding relative satellite orbits that guarantee long-term bounded relative motion is important for cluster flight, wherein a group of satellites remain within bounded distances while applying very few formationkeeping maneuvers. However, most existing astrodynamical approaches utilize mean orbital elements for detecting bounded relative orbits, and therefore cannot guarantee long-term boundedness under realistic gravitational models. The main purpose of the present paper is to develop analytical methods for designing long-term bounded relative orbits under high-order gravitational perturbations. The key underlying observation is that in the presence of arbitrarily high-order even zonal harmonics perturbations, the dynamics are superintegrable for equatorial orbits. When only J [SUB]2[/SUB] is considered, the current paper offers a closed-form solution for the relative motion in the equatorial plane using elliptic integrals. Moreover, necessary and sufficient periodicity conditions for the relative motion are determined. The proposed methodology for the J2-perturbed relative motion is then extended to non-equatorial orbits and to the case of any high-order even zonal harmonics ( J2n, n ≥ 1). Numerical simulations show how the suggested methodology can be implemented for designing bounded relative quasiperiodic orbits in the presence of the complete zonal part of the gravitational potential. [less ▲]

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See detailLa production de biohydrogène à partir de substrats carbohydratés : état de l'art
Hiligsmann, Serge ULg; Beckers, Laurent ULg; Masset, Julien ULg et al

in Récents progrès en génie des procédés (2011, December 01)

Hydrogen is being considered as an ideal and clean energy carrier. The recent advances to produce biohydrogen from renewable sources such as biomass and particularly by fermentation of carbohydrate-rich ... [more ▼]

Hydrogen is being considered as an ideal and clean energy carrier. The recent advances to produce biohydrogen from renewable sources such as biomass and particularly by fermentation of carbohydrate-rich substrates from agriculture and agro-industries appear promising. Such a process enables both organic waste treatment and renewable energy production to be coupled. The paper presents the state of the art about the different hydrogen-producing microorganisms and the parameters that have been investigated in order to improve the hydrogen production yields and rates. [less ▲]

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See detailRotation on the oscillation spectrum of solar-like stars
Suárez, J. C.; Goupil, M.-J.; Reese, Daniel ULg et al

in Alecian, G.; Belkacem, K.; Samadi, R. (Eds.) et al SF2A-2011: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics (2011, December 01)

One of the main sources of uncertainty in the asteroseismic models of solar-like stars is the poor match between predicted oscillation frequencies and observed ones in the very high frequency domain ... [more ▼]

One of the main sources of uncertainty in the asteroseismic models of solar-like stars is the poor match between predicted oscillation frequencies and observed ones in the very high frequency domain. Today, such deviation is usually corrected by fitting the affected frequencies with polynomials which are then physically explained by possible effects of turbulence, diffusion, etc., i.e., the so-called ``surface effects". In this work, we show that the effect of the stellar deformation due to rotation is of the same order or even larger than the aforementioned surface effects. Moreover, we show that rotation effects, even for the low velocities generally observed in solar-like stars, becomes important for the asteroseismic analysis and cannot be neglected when modeling such stars. [less ▲]

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See detailThérapie du mésothéliome pleural : compréhension des mécanismes de résistance à la chimiothérapie
Costa, Chrisostome ULg; Vandermeers, Fabian ULg; Reddy, NS Sathyanarayana ULg et al

Diverse speeche and writing (2011)

Thérapie du mésothéliome pleural : compréhension des mécanismes de résistance à la chimiothérapie. Chrisostome Costa 1, Fabian Vandermeers 2, Sathyanarayana Reddy 2, Céline Mascaux 3, Pascale Hubert 2 ... [more ▼]

Thérapie du mésothéliome pleural : compréhension des mécanismes de résistance à la chimiothérapie. Chrisostome Costa 1, Fabian Vandermeers 2, Sathyanarayana Reddy 2, Céline Mascaux 3, Pascale Hubert 2, Philippe Delvenne 2, Luc Willems 1,2 1 Laboratoire de biologie cellulaire et moléculaire, ULg, Gemboux Agro Bio-Tech, 13 av. Maréchal Juin, 5030 Gembloux ; Tél. : 32-(0)-81-622157 ; Fax : 32-(0)-81-6138 88 ; Courriel: ccosta@doct.ulg.ac.be 2 GIGA, ULg, Liège 3 Institut Bordet, ULB, Bruxelles - Introduction : Le mésothéliome pleural malin (MPM) est un cancer de la plèvre causé principalement par l’inhalation de fibres d’amiante. Nous avons montré précédemment que les inhibiteurs d’histones deacetylases (tel que le valproate, VPA) augmentent significativement l’efficacité des composés utilisés en chimiothérapie (pemetrexed et cisplatin) et prolonge la survie des patients atteints de MPM. Malheureusement, une proportion importante des patients développe une résistance au traitement de seconde ligne avec la doxorubicine et le VPA. - But du projet : L’objectif du travail est de disséquer les mécanismes qui régissent la réponse au traitement de seconde ligne du MPM. - Méthodes et résultats : Nous avons tout d’abord comparé deux types de lignées cellulaires présentant soit une sensibilité (cellules M14K) soit une résistance (cellules H28) au traitement combiné VPA+doxorubicine. En utilisant des microdamiers (Agilent), nous avons analysé le profil d’expression génique de cellules M14K et H28 traitées avec le VPA et la doxorubicine. Après quantification des fluorescences, une analyse statistique (Genespring GX) et une modélisation bioinformatique (Ingenuity) ont permis d’identifier les gènes candidats les plus relevants. En fonction de la p-value et du fold change, un nombre limité de gènes ont été sélectionnés et validés par la technique de qRT-PCR. Parmi ceux-ci, nous avons identifié le gène TGFA dont l’expression corrèle avec la résistance au traitement. En effet, nous avons observé que le niveau d’expression basale du gène TGFA est beaucoup plus important dans la lignée résistante H28 que dans la lignée sensible M14K. Dans le but de valider son implication dans la réponse à la thérapie, nous avons diminué (par interférence ARN) ou augmenté (par transfection d’un vecteur d’expression) l’expression de TGFA respectivement dans les lignées H28 ou M14K. Nous avons ensuite déterminé les taux d’apoptose en évaluant la fragmentation de l’ADN en présence de doxorubicine et de VPA. Les résultats montrent que la diminution de l’expression de TGFA permet une augmentation sensible de l’apoptose induite par le traitement combiné doxorubicine et VPA dans la lignée résistante H28 (de 9% à 36%). A l’inverse, la surexpression de TGFA est associée avec une diminution d’apoptose dans la lignée sensible M14K (de 28% à 18%). Ces observations ont été confirmées par une analyse de l’activité des caspases 3 et 7. En accord avec la propriété de la protéine TGFAd’induire la prolifération cellulaire via le récepteur à l’EGF, des inhibiteurs de l’activité tyrosine kinase (l’Iressa et le Tarceva) augmentent l’apoptose induite par la doxorubicine et le VPA dans la lignée résistante H28 (de 16% à 40%). L’efficacité du traitement combiné VPA+doxorubicine+Iressa/Tarceva est actuellement évaluée en modèle murin (souris SCID). - Conclusions : Nous avons identifié un gène, le TGFA, dont l’expression corrèle avec la résistance à l’apoptose induite par la doxorubicine et le VPA. L’utilisation d’inhibiteurs du récepteur EGF pourrait donc améliorer le traitement de seconde ligne du MPM. [less ▲]

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See detailLa disposition générale anti-abus de l'article 344, § 1er, CIR/92
Bourgeois, Marc ULg

Conference (2011, December 01)

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See detailOpening the door is not sufficient : each child has rights to take part in the everyday life of an ECEC service
Camus, Pascale ULg

Conference (2011, December 01)

Despite the fact that Belgium has ratified the UN Convention on the Rights of the Child in 1992, few children with special needs are taken care of in mainstream services. When they have access to a ... [more ▼]

Despite the fact that Belgium has ratified the UN Convention on the Rights of the Child in 1992, few children with special needs are taken care of in mainstream services. When they have access to a service, everything is focused on their deficiency. Professionals think they have to be trained to give what is considered as the “right” treatment to make the child « catch the others up ». There is an alternative way of thinking that focuses on each child’s competences. Adopting this way of thinking means to consider that what matters is every little thing a child can bring to the group, whatever his characteristics may be, and how he can benefit from daily life with other children and adults. The workshop has been focused on conditions that can help increase quality provisions : Who is welcomed everyday? How does an ECEC service welcome each family? Are there children and families who don’t come to ECEC services? Why don’t they come? Are they sufficiently informed on the inclusive approach of ECEC services, Etc The conference has referred to some testimonies collected by professionals from the French Community of Belgium. [less ▲]

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See detailSaturn's aurora as viewed by Cassini VIMS
Melin, H.; Stallard, T.; Badman, S. V. et al

Conference (2011, December 01)

The stunning views of the kronian aurora captured by the Visual and Infrared Imaging Spectrograph (VIMS) onboard the Cassini spacecraft continues to provide crucial observations of the fervent interaction ... [more ▼]

The stunning views of the kronian aurora captured by the Visual and Infrared Imaging Spectrograph (VIMS) onboard the Cassini spacecraft continues to provide crucial observations of the fervent interaction between the upper atmosphere and the magnetosphere of Saturn. Here, we present recent findings of VIMS auroral research, which includes both statistical studies and case studies of auroral events and morphology. In addition to stand-alone observations, there is a small subset of VIMS observations during which UVIS was also acquiring data. These observations enable the comparison between observations of H, H2 in the ultraviolet and H3+ in the infrared that are both spatially overlapping and temporally simultaneous. Whilst emission tends to coincide for these three species on the main oval, there are significant differences both pole-ward and equator-ward, such that observations of H and H2 is generally a poor proxy for emissions of H3+. VIMS is sensitive to infrared thermal emission from the H3+ molecule, which is formed very efficiently via the ionisation of H2. Therefore, the morphology of H3+ emission becomes a tracer of energy injected into the upper atmosphere - the most striking of which is auroral particle precipitation. [less ▲]

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See detailL'astronomie dans le monde
Manfroid, Jean ULg

in Ciel (Le) (2011), 73

Rosetta et Lutétia; Eau et disque proto-planétaire; Nouveaux amas; Galaxies primitives; Trou noir supermassif; Réionisation et premières étoiles; FERMI; ALMA

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See detailAuroral counterpart of magnetic field dipolarizations in Saturn's tail
Jackman, C. M.; Achilleos, N.; Bunce, E. J. et al

in American Geophysical Union, Fall Meeting 2011, abstract #SM14A-07 (2011, December 01)

Following magnetic reconnection in a planetary magnetotail, newly closed field lines can be rapidly accelerated back towards the planet, becoming "dipolarized" in the process. At Saturn, dipolarizations ... [more ▼]

Following magnetic reconnection in a planetary magnetotail, newly closed field lines can be rapidly accelerated back towards the planet, becoming "dipolarized" in the process. At Saturn, dipolarizations can be initially identified from the magnetometer data by looking for a southward turning of the magnetic field, indicating the transition from a radially stretched configuration to a more dipolar field topology. The highly stretched geometry of the kronian magnetotail lobes gives rise to a tail current which flows eastward (dusk to dawn) in the near equatorial plane across the centre of the tail. During reconnection and associated dipolarization of the field, the inner edge of this tail current can be diverted through the ionosphere, in a situation analogous to the substorm current wedge picture at Earth [McPherron et al. 1973]. We present a picture of the current circuit arising from this tail reconfiguration, and outline the equations which govern the field-current relationship. We show a number of examples of dipolarizations as identified in the Cassini magnetometer data and use this formalism to calculate limits for the ionospheric current density that would arise for these examples. In addition to the magnetometer data, we also present data from the Cassini VIMS and UVIS instruments which have observed small 'spots' of auroral emission lying near the main oval - features thought to be associated with dipolarizations in the tail. We compare the auroral intensities as predicted from our calculation with the observed spot sizes and intensities. [less ▲]

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See detailCassini UVIS Observations of Titan Ultraviolet Airglow Spectra with Laboratory Modeling from Electron- and Proton-Excited N2 Emission Studies
Ajello, J. M.; West, R. A.; Malone, C. P. et al

Conference (2011, December 01)

Joseph M. Ajello, Robert A. West, Rao S. Mangina Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 Charles P. Malone Jet Propulsion Laboratory, California Institute of ... [more ▼]

Joseph M. Ajello, Robert A. West, Rao S. Mangina Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 Charles P. Malone Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 & Department of Physics, California State University, Fullerton, CA 92834 Michael H. Stevens Space Science Division, Naval Research Laboratory, Washington, DC 20375 Jacques Gustin Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liège, Belgium A. Ian F. Stewart, Larry W. Esposito, William E. McClintock, Gregory M. Holsclaw Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 E. Todd Bradley Department of Physics, University of Central Florida, Orlando, FL 32816 The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including three eclipse observations from 2009 through 2010. The 77 airglow observations analyzed in this paper show EUV (600-1150 Å) and FUV (1150-1900 Å) atomic multiplet lines and band emissions (lifetimes less than ~100 μs), including the Lyman-Birge-Hopfield (LBH) band system, arising from photoelectron induced fluorescence and solar photo-fragmentation of molecular nitrogen (N2). The altitude of peak UV emission on the limb of Titan during daylight occurred inside the thermosphere/ionosphere (near 1000 km altitude). However, at night on the limb, the same emission features, but much weaker in intensity, arise in the lower atmosphere below 1000 km (lower thermosphere, mesosphere, haze layer) extending downwards to near the surface at ~300 km, possibly resulting from proton- and/or heavier ion-induced emissions as well as secondary-electron-induced emissions. The eclipse observations are unique. UV emissions were observed during only one of the three eclipse events, and no Vegard-Kaplan (VK) or LBH emissions were seen. Through regression analysis using laboratory spectra, we have analyzed the intensity and identified each spectral feature from the limb or disk emission spectrum. The strongest dipole-allowed transitions of N2 occur in the EUV. The electronic transitions proceed from the X 1Σg+ ground-state to about seven closely spaced (~12-15 eV) Rydberg-valence (RV) states, which are the source of the molecular emissions in the EUV observed by spacecraft and have recently been studied in our laboratory at medium-to-high spectral resolution (delta-λ = 0.1 Å FWHM). Three of these RV states (b 1Πu, b' 1Σu+, and c4' 1Σu+) are highly-perturbed, weakly-to-strongly predissociated, and have significant emission cross sections, which will be summarized in this paper. We will also discuss our recently published proton and electron impact emission cross sections for the LBH (a 1Πg - X 1Σg+) band system of N2, and their significance to the modeling of the day and night FUV spectra of the atmospheres of Earth and Titan. [less ▲]

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See detailEtude de l’écoulement au sein d’un bioréacteur parallélépipédique à usage unique à agitation pendulo-elliptique
Collignon, Marie-Laure ULg; Droissart, Laurent; Delafosse, Angélique ULg et al

in Récents Progrès en Génie des procédés - A la croisée des sciences et des cultures, pour relever les défis industriels du XXIème siècle (2011, December 01)

Les bioréacteurs à usage unique sont de plus en plus envisagés dans l’industrie pharmaceutique en remplacement de leurs homologues en acier car ils permettent d’éliminer les étapes de lavage et de ... [more ▼]

Les bioréacteurs à usage unique sont de plus en plus envisagés dans l’industrie pharmaceutique en remplacement de leurs homologues en acier car ils permettent d’éliminer les étapes de lavage et de stérilisation tout en réduisant le risque de contamination croisée. Afin de s’insérer dans ce marché en expansion, les firmes ATMI LifeSciences, Pierre Guerrin et Artelis ont développé un bioréacteur à usage unique « Nucleo » composé d’une poche parallélépipédique en plastique souple mélangée par une pale réalisant un mouvement pendulo-elliptique. Différentes études ont démontré les bonnes performances de ce dispositif en termes d’homogénéisation et de maintien en suspension d’une phase solide ainsi que des productivités intéressantes lors de la réalisation de cultures de cellules animales. L’objectif de la présente étude est de caractériser l’écoulement du liquide au sein du bioréacteur grâce à des mesures réalisées par stéréo PIV. L’analyse des profils de vitesse a montré, qu’aux vitesses de rotation étudiées, l’écoulement au sein de la cuve est turbulent. Il apparaît que dans ces conditions, l’écoulement est complètement tridimensionnel et forme une spirale toroïdale plus ou moins déformée autour de l’axe central de la cuve. Il présente une certaine symétrie par rapport à cet axe central. Bien que la cuve soit parallélépipédique, aucune zone morte n’est observée dans les coins de celle-ci. [less ▲]

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See detailHerschel discovery of a new class of cold, faint debris discs
Eiroa, C.; Marshall, J. P.; Mora, A. et al

in Astronomy and Astrophysics (2011), 536

We present Herschel PACS 100 and 160 μm observations of the solar-type stars α Men, HD 88230 and HD 210277, which form part of the FGK stars sample of the Herschel open time key programme (OTKP) DUNES ... [more ▼]

We present Herschel PACS 100 and 160 μm observations of the solar-type stars α Men, HD 88230 and HD 210277, which form part of the FGK stars sample of the Herschel open time key programme (OTKP) DUNES (DUst around NEarby Stars). Our observations show small infrared excesses at 160 μm for all three stars. HD 210277 also shows a small excess at 100 μm, while the 100 μm fluxes of α Men and HD 88230 agree with the stellar photospheric predictions. We attribute these infrared excesses to a new class of cold, faint debris discs. Both α Men and HD 88230 are spatially resolved in the PACS 160 μm images, while HD 210277 is point-like at that wavelength. The projected linear sizes of the extended emission lie in the range from ~115 to ≤ 250 AU. The estimated black body temperatures from the 100 and 160 μm fluxes are ≲22 K, and the fractional luminosity of the cold dust is L[SUB]dust[/SUB]/L[SUB] ⋆ [/SUB] ~ 10[SUP]-6[/SUP], close to the luminosity of the solar-system's Kuiper belt. These debris discs are the coldest and faintest discs discovered so far around mature stars, so they cannot be explained easily invoking "classical" debris disc models. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. [less ▲]

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See detailFirst HARPSpol discoveries of magnetic fields in massive stars
Alecian, E.; Kochukhov, O.; Neiner, C. et al

in Astronomy and Astrophysics (2011), 536

In the framework of the Magnetism in Massive Stars (MiMeS) project, a HARPSpol Large Program at the 3.6m-ESO telescope has recently started to collect high-resolution spectropolarimetric data of a large ... [more ▼]

In the framework of the Magnetism in Massive Stars (MiMeS) project, a HARPSpol Large Program at the 3.6m-ESO telescope has recently started to collect high-resolution spectropolarimetric data of a large number of Southern massive OB stars in the field of the Galaxy and in many young clusters and associations. We report on the first discoveries of magnetic fields in two massive stars with HARPSpol - HD 130807 and HD 122451, and confirm the presence of a magnetic field at the surface of HD 105382 that was previously observed with a low spectral resolution device. The longitudinal magnetic field measurements strongly vary for HD 130807 from ~-100 G to ~700 G. Those of HD 122451 and HD 105382 are less variable with values ranging from ~-40 to -80 G, and from ~-300 to -600 G, respectively. The discovery and confirmation of three new magnetic massive stars, including at least two He-weak stars, is an important contribution to one of MiMeS objectives: the understanding of the origin of magnetic fields in massive stars and their impact on stellar structure and evolution. Based on observations collected at the European Southern Observatory, Chile (Program ID 187.D-0917). [less ▲]

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See detailL'allergie au liquide séminal
DEZFOULIAN, Bita ULg; RATY, Laurent ULg; NIKKELS, Arjen ULg

in Skin Inc (2011), 14(N°5), 140

L'allergie au liquide séminal est une affection rare dont le diagnostic est difficile et souvent tardif. Divers degrés de sévérité clinique peuvent se rencontrer, allant d'une forme fruste, chronique et ... [more ▼]

L'allergie au liquide séminal est une affection rare dont le diagnostic est difficile et souvent tardif. Divers degrés de sévérité clinique peuvent se rencontrer, allant d'une forme fruste, chronique et localisée, à une symptomatologie aiguë pouvant conduire au choc anaphylactique. Des réactions croisées ont récemment été identifiées entre certains allergènes prostatiques humains et certains allergènes du chien. Ce phénomène pourrait expliquer l'apparition d'une réaction allergique au liquide séminal dès le premier rapport. Nous présentons ici le cas d'une jeune femme avec une allergie au liquide séminal, mise en évidence par un prick test positif à un extrait centrifugé et filtré à partir du sperme de son partenaire. [less ▲]

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See detailMagnetic field studies of massive main sequence stars
Schöller, M.; Hubrig, S.; Ilyin, I. et al

in Astronomische Nachrichten (2011), 332

We report on the status of our spectropolarimetric observations of massive stars. During the last years, we have discovered magnetic fields in many objects of the upper main sequence, including Be stars ... [more ▼]

We report on the status of our spectropolarimetric observations of massive stars. During the last years, we have discovered magnetic fields in many objects of the upper main sequence, including Be stars, β Cephei and Slowly Pulsating B stars, and a dozen O stars. Since the effects of those magnetic fields have been found to be substantial by recent models, we are looking into their impact on stellar rotation, pulsation, stellar winds, and chemical abundances. Accurate studies of the age, environment, and kinematic characteristics of the magnetic stars are also promising to give us new insight into the origin of the magnetic fields. Furthermore, longer time series of magnetic field measurements allow us to observe the temporal variability of the magnetic field and to deduce the stellar rotation period and the magnetic field geometry. Studies of the magnetic field in massive stars are indispensable to understand the conditions controlling the presence of those fields and their implications on the stellar physical parameters and evolution. [less ▲]

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See detailSpectroscopic variability and magnetic fields of HgMn stars
Hubrig, S.; González, J. F.; Ilyin, I. et al

in Astronomische Nachrichten (2011), 332

The discovery of exotic abundances, chemical inhomogeneities, and weak magnetic fields on the surface of late B-type primaries in spectroscopic binaries has important implications not only for our ... [more ▼]

The discovery of exotic abundances, chemical inhomogeneities, and weak magnetic fields on the surface of late B-type primaries in spectroscopic binaries has important implications not only for our understanding of the formation mechanisms of stars with Hg and Mn peculiarities themselves, but also for the general understanding of B-type star formation in binary systems. The origin of the abundance anomalies observed in late B-type stars with HgMn peculiarity is still poorly understood. The connection between HgMn peculiarity and membership in binary and multiple systems is supported by our observations during the last decade. The important result achieved in our studies of a large sample of HgMn stars is the finding that most HgMn stars exhibit spectral variability of various chemical elements, proving that the presence of an inhomogeneous distribution on the surface of these stars is a rather common characteristic and not a rare phenomenon. Further, in the studied systems, we found that all components are chemically peculiar with different abundance patterns. Generally, He and Si variable Bp stars possess large-scale organised magnetic fields that in many cases appear to occur essentially in the form of a single large dipole located close to the centre of the star. The presence of magnetic fields in the atmospheres of HgMn stars has been demonstrated in several studies. In addition to the measurements of longitudinal and quadratic magnetic fields, this work also showed evidence for a relative magnetic intensification of Fe II lines produced by different magnetic desaturations induced by different Zeeman-split components. Based on ESO Archival data, from ESO programme 083.D-1000(A). [less ▲]

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See detailHigh-contrast Stellar Observations within the Diffraction Limit at the Palomar Hale Telescope
Mennesson, B.; Hanot, Charles ULg; Serabyn, Eugene et al

in Astrophysical Journal (2011), 743

We report on high-accuracy high-resolution (<20 mas) stellar observations obtained with the Palomar Fiber Nuller (PFN), a near-infrared (sime2.2 μm) interferometric coronagraph installed at the Palomar ... [more ▼]

We report on high-accuracy high-resolution (<20 mas) stellar observations obtained with the Palomar Fiber Nuller (PFN), a near-infrared (sime2.2 μm) interferometric coronagraph installed at the Palomar Hale telescope. The PFN uses destructive interference between two elliptical (3 m × 1.5 m) sub-apertures of the primary to reach high dynamic range inside the diffraction limit of the full telescope. In order to validate the PFN's instrumental approach and its data reduction strategy, based on the newly developed "Null Self-Calibration" (NSC) method, we observed a sample of eight well-characterized bright giants and supergiants. The quantity measured is the source astrophysical null depth, or equivalently the object's visibility at the PFN 3.2 m interferometric baseline. For the bare stars α Boo, α Her, β And, and α Aur, PFN measurements are in excellent agreement with previous stellar photosphere measurements from long baseline interferometry. For the mass-losing stars β Peg, α Ori, ρ Per, and χ Cyg, circumstellar emission and/or asymmetries are detected. Overall, these early observations demonstrate the PFN's ability to measure astrophysical null depths below 10[SUP]-2[/SUP] (limited by stellar diameters), with 1 σ uncertainties as low as a few 10[SUP]-4[/SUP]. Such visibility accuracy is unmatched at this spatial resolution in the near-infrared and translates into a contrast better than 10[SUP]-3[/SUP] within the diffraction limit. With further improvements anticipated in 2011/2012, a state-of-the-art infrared science camera and a new extreme adaptive optics system, the PFN should provide a unique tool for the detection of hot debris disks and young self-luminous sub-stellar companions in the immediate vicinity of nearby stars. [less ▲]

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See detailPRISE EN CHARGE MULTIDISCIPLINAIRE DE L'INSUFFISANCE CARDIAQUE DU SUJET AGE
NELLESSEN, Eric ULg; ENGLEBERT, J; Petermans, Jean ULg

Conference (2011, December 01)

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See detailCoRoT's view on variable B8/9 stars: spots versus pulsations. Evidence for differential rotation in HD 174648
Degroote, P.; Acke, B.; Samadi, R. et al

in Astronomy and Astrophysics (2011), 536

Context. There exist few variability studies of stars in the region in the Hertzsprung-Russell diagram between the A and B-star pulsational instability strips. With the aid of the high precision ... [more ▼]

Context. There exist few variability studies of stars in the region in the Hertzsprung-Russell diagram between the A and B-star pulsational instability strips. With the aid of the high precision continuous measurements of the CoRoT space satellite, low amplitudes are more easily detected, making a study of this neglected region worthwhile. <BR /> Aims: We collected a small sample of B stars observed by CoRoT to determine the origin of the different types of variability observed. <BR /> Methods: We combine literature photometry and spectroscopy to measure the fundamental parameters of the stars in the sample, and compare asteroseismic modelling of the light curves with (differentially rotating) spotted star models. <BR /> Results: We found strong evidence for the existence of spots and differential rotation in HD 174648, and formulated hypotheses for their origin. We show that the distinction between pulsations and rotational modulation is difficult to make solely based on the light curve, especially in slowly rotating stars. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.Based on observations made with the ESO telescopes at La Silla Observatory under the ESO Large Programme LP182.D-0356.Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.Appendix A is available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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