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See detailMontages structuralistes dans Les Temps Modernes
Cormann, Grégory ULiege

Scientific conference (2017, October 02)

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See detailNotebooks for documenting work-flows
Troupin, Charles ULiege; Barth, Alexander ULiege; Muñoz, Cristian et al

Conference (2017, October 02)

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See detailExozodiacal disks
Absil, Olivier ULiege; Ertel, Steve

Conference (2017, October 02)

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See detailPHILOSTORY : autour du spectacle d’Isabelle Pousseur « Last Exit to Brooklyn (Coda) » (Hubert Selby Jr.)
Hagelstein, Maud ULiege; Janvier, Antoine ULiege; Despret, Vinciane ULiege et al

Conference given outside the academic context (2017)

Quels liens peut-on tracer entre le retour du loup dans les forêts des Cévennes et la vie dans les communautés urbaines de Brooklyn ? Ce grand écart apparent constitue le défi pour la pensée de la ... [more ▼]

Quels liens peut-on tracer entre le retour du loup dans les forêts des Cévennes et la vie dans les communautés urbaines de Brooklyn ? Ce grand écart apparent constitue le défi pour la pensée de la prochaine soirée Philostory organisée au Théâtre de Liège (02/10). D’un côté, le spectacle d’Isabelle Pousseur, Last Exit to Brooklyn (Coda), au départ du texte que Hubert Selby Jr. consacre à la vie d’un immeuble dans une grande ville des Etats-Unis et aux rapports sociaux qui s’y nouent. De l’autre, l’expérience inédite d’un philosophe cherchant à penser le retour spontané du loup en France, et construisant à partir de là de nouvelles figures du « diplomate ». En croisant ces deux récits, on pourra envisager de nouvelles formes de cohabitation, de nouvelles façons de composer les relations, qui prennent en compte sans les nier la peur du sauvage, la violence (puissance de conflit), la promiscuité, le sens du territoire, l’inégalité des rapports, mais aussi la nécessité des alliances et de l’invention d’un langage commun. Vers un modèle différent de la diplomatie. [less ▲]

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See detailProbing dark matter substructure in the gravitational lens HE 0435‑1223 with the WFC3 grism
Nierenberg, A. M.; Treu, T.; Brammer, G. et al

in Monthly Notices of the Royal Astronomical Society (2017), 471

Strong gravitational lensing provides a powerful test of Cold Dark Matter (CDM) as it enables the detection and mass measurement of low mass haloes even if they do not contain baryons. Compact lensed ... [more ▼]

Strong gravitational lensing provides a powerful test of Cold Dark Matter (CDM) as it enables the detection and mass measurement of low mass haloes even if they do not contain baryons. Compact lensed sources such as Active Galactic Nuclei (AGN) are particularly sensitive to perturbing subhalos, but their use as a test of CDM has been limited by the small number of systems which have significant radio emission which is extended enough avoid significant lensing by stars in the plane of the lens galaxy, and red enough to be minimally affected by differential dust extinction. Narrow-line emission is a promising alternative as it is also extended and, unlike radio, detectable in virtually all optically selected AGN lenses. We present first results from a WFC3 grism narrow-line survey of lensed quasars, for the quadruply lensed AGN HE0435-1223. Using a forward modelling pipeline which enables us to robustly account for spatial blending, we measure the [OIII] 5007 \AA~ flux ratios of the four images. We find that the [OIII] fluxes and positions are well fit by a simple smooth mass model for the main lens. Our data rule out a $M_{600}>10^{8} (10^{7.2}) M_\odot$ NFW perturber projected within $\sim$1\farcs0 (0\farcs1) arcseconds of each of the lensed images, where $M_{600}$ is the perturber mass within its central 600 pc. The non-detection is broadly consistent with the expectations of $\Lambda$CDM for a single system. The sensitivity achieved demonstrates that powerful limits on the nature of dark matter can be obtained with the analysis of $\sim20$ narrow-line lenses. [less ▲]

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See detailWhat CoRoT tells us about δ Scuti stars. Existence of a regular pattern and seismic indices to characterize stars
Michel, Eric; Dupret, Marc-Antoine ULiege; Reese, Daniel et al

in European Physical Journal Web of Conferences (2017, October 01), 160

Inspired by the so appealing example of red giants, where going from a handful of stars to thousands revealed the structure of the eigenspectrum, we inspected a large homogeneous set of around 1860 δ ... [more ▼]

Inspired by the so appealing example of red giants, where going from a handful of stars to thousands revealed the structure of the eigenspectrum, we inspected a large homogeneous set of around 1860 δ Scuti stars observed with CoRoT. This unique data set reveals a common regular pattern which appears to be in agreement with island modes featured by theoretical non-perturbative treatments of fast rotation. The comparison of these data with models and linear stability calculations suggests that spectra can be fruitfully characterized to first order by a few parameters which might play the role of seismic indices for δ Scuti stars, as Δv and v[SUB]max[/SUB] do for red giants. The existence of this pattern offers an observational support for guiding further theoretical works on fast rotation. It also provides a framework for further investigation of the observational material collected by CoRoT ([1]) and Kepler ([2]). Finally, it sketches out the perspective of using δ Scuti stars pulsations for ensemble asteroseismology [less ▲]

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See detailBayesian Multi-Objective Optimisation of Neotissue Growth in a Perfusion Bioreactor Set-up
olofsson, Simon; Mehrian, Mohammad ULiege; Geris, Liesbet ULiege et al

Scientific conference (2017, October 01)

We consider optimising bone neotissue growth in a 3D scaffold during dynamic perfusion bioreactor culture. The goal is to choose design variables by optimising two conflicting objectives: (i) maximising ... [more ▼]

We consider optimising bone neotissue growth in a 3D scaffold during dynamic perfusion bioreactor culture. The goal is to choose design variables by optimising two conflicting objectives: (i) maximising neotissue growth and (ii) minimising operating cost. Our contribution is a novel extension of Bayesian multi-objective optimisation to the case of one black-box (neotissue growth) and one analytical (operating cost) objective function, that helps determine, within a reasonable amount of time, what design variables best manage the trade-off between neotissue growth and operating cost. Our method is tested against and outperforms the most common approach in literature, genetic algorithms, and shows its important real-world applicability to problems that combine black-box models with easy-to-quantify objectives like cost. [less ▲]

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See detailDevelopment of real-time PCR targets for the detection of Tenebrio molitor and Hermetia illucens
Marien, Aline; Debode, Frédéric; Aerts, Céline et al

Poster (2017, October 01)

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See detailH0LiCOW - II. Spectroscopic survey and galaxy-group identification of the strong gravitational lens system HE 0435-1223
Sluse, Dominique ULiege; Sonnenfeld, A.; Rumbaugh, N. et al

in Monthly Notices of the Royal Astronomical Society (2017), 470

Galaxies located in the environment or along the line of sight towards gravitational lenses can significantly affect lensing observables, and can lead to systematic errors on the measurement of H[SUB]0 ... [more ▼]

Galaxies located in the environment or along the line of sight towards gravitational lenses can significantly affect lensing observables, and can lead to systematic errors on the measurement of H[SUB]0[/SUB] from the time-delay technique. We present the results of a systematic spectroscopic identification of the galaxies in the field of view of the lensed quasar HE 0435-1223 using the W. M. Keck, Gemini and ESO-Very Large telescopes. Our new catalogue triples the number of known galaxy redshifts in the direct vicinity of the lens, expanding to 102 the number of measured redshifts for galaxies separated by less than 3 arcmin from the lens. We complement our catalogue with literature data to gather redshifts up to 15 arcmin from the lens, and search for galaxy groups or clusters projected towards HE 0435-1223. We confirm that the lens is a member of a small group that includes at least 12 galaxies, and find 8 other group candidates near the line of sight of the lens. The flexion shift, namely the shift of lensed images produced by high-order perturbation of the lens potential, is calculated for each galaxy/group and used to identify which objects produce the largest perturbation of the lens potential. This analysis demonstrates that (i) at most three of the five brightest galaxies projected within 12 arcsec of the lens need to be explicitly used in the lens models, and (ii) the groups can be treated in the lens model as an external tidal field (shear) contribution. [less ▲]

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See detailThe Structure of Chariklo’s Rings from Stellar Occultations
Bérard, D.; Sicardy, B.; Camargo, J. I. B. et al

in Astronomical Journal (The) (2017), 154

Two narrow and dense rings (called C1R and C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned ... [more ▼]

Two narrow and dense rings (called C1R and C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned observations of several occultations by Chariklo’s system in order to better characterize the physical properties of the ring and main body. Here, we use 12 successful occulations by Chariklo observed between 2014 and 2016. They provide ring profiles (physical width, opacity, edge structure) and constraints on the radii and pole position. Our new observations are currently consistent with the circular ring solution and pole position, to within the ±3.3 km formal uncertainty for the ring radii derived by Braga-Ribas et al. The six resolved C1R profiles reveal significant width variations from ∼5 to 7.5 km. The width of the fainter ring C2R is less constrained, and may vary between 0.1 and 1 km. The inner and outer edges of C1R are consistent with infinitely sharp boundaries, with typical upper limits of one kilometer for the transition zone between the ring and empty space. No constraint on the sharpness of C2R’s edges is available. A 1σ upper limit of ∼20 m is derived for the equivalent width of narrow (physical width < 4 km) rings up to distances of 12,000 km, counted in the ring plane. [less ▲]

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See detailSPECULOOS exoplanet search and its prototype on TRAPPIST
Burdanov, Artem ULiege; Delrez, Laetitia; Gillon, Michaël ULiege et al

E-print/Working paper (2017)

One of the most significant goals of modern science is establishing whether life exists around other suns. The most direct path towards its achievement is the detection and atmospheric characterization of ... [more ▼]

One of the most significant goals of modern science is establishing whether life exists around other suns. The most direct path towards its achievement is the detection and atmospheric characterization of terrestrial exoplanets with potentially habitable surface conditions. The nearest ultracool dwarfs (UCDs), i.e. very-low-mass stars and brown dwarfs with effective temperatures lower than 2700 K, represent a unique opportunity to reach this goal within the next decade. The potential of the transit method for detecting potentially habitable Earth-sized planets around these objects is drastically increased compared to Earth-Sun analogs. Furthermore, only a terrestrial planet transiting a nearby UCD would be amenable for a thorough atmospheric characterization, including the search for possible biosignatures, with near-future facilities such as the James Webb Space Telescope. In this chapter, we first describe the physical properties of UCDs as well as the unique potential they offer for the detection of potentially habitable Earth-sized planets suitable for atmospheric characterization. Then, we present the SPECULOOS ground-based transit survey, that will search for Earth-sized planets transiting the nearest UCDs, as well as its prototype survey on the TRAPPIST telescopes. We conclude by discussing the prospects offered by the recent detection by this prototype survey of a system of seven temperate Earth-sized planets transiting a nearby UCD, TRAPPIST-1. [less ▲]

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See detailMars’ seasonal mesospheric transport seen through nitric oxide nightglow
Milby, Zachariah; Stiepen, Arnaud ULiege; Jain, Sonal et al

Conference (2017, October 01)

We analyze the ultraviolet nightglow in the atmosphere of Mars through nitric oxide (NO) δ and γ band emissions as observed by the Imaging UltraViolet Spectrograph (IUVS) instrument onboard the Mars ... [more ▼]

We analyze the ultraviolet nightglow in the atmosphere of Mars through nitric oxide (NO) δ and γ band emissions as observed by the Imaging UltraViolet Spectrograph (IUVS) instrument onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft when it is at apoapse and periapse.In the dayside thermosphere of Mars, solar extreme-ultraviolet radiation dissociates CO[SUB]2[/SUB] and N[SUB]2[/SUB] molecules. O([SUP]3[/SUP]P) and N([SUP]4[/SUP]S) atoms are carried from the dayside to the nightside by the day-night hemispheric transport process, where they descend through the nightside mesosphere and can radiatively recombine to form NO(C[SUP]2[/SUP]Π). The excited molecules rapidly relax by emitting photons in the UV δ and γ bands. These emissions are indicators of the N and O atom fluxes from the dayside to Mars’ nightside and the descending circulation pattern from the nightside thermosphere to the mesosphere (e.g. Bertaux et al., 2005 ; Bougher et al., 1990 ; Cox et al., 2008 ; Gagné et al., 2013 ; Gérard et al., 2008 ; Stiepen et al., 2015, 2017).Observations of these emissions are gathered from a large dataset spanning different seasonal conditions.We present discussion on the variability in the brightness and altitude of the emission with season, geographical position (longitude), and local time, along with possible interpretation by local and global changes in the mesosphere dynamics. We show the possible impact of atmospheric waves forcing longitudinal variability and data-to-model comparisons indicating a wave-3 structure in Mars’ nightside mesosphere. Quantitative comparison with calculations of the Laboratoire de Météorologie Dynamique-Mars Global Climate Model (LMD-MGCM) suggests the model reproduces both the global trend of NO nightglow emission and its seasonal variation. However, it also indicates large discrepancies, with the emission up to a factor 50 times fainter in the model, suggesting that the predicted transport is too efficient toward the night winter pole in the thermosphere by ˜20° latitude to the north.These questions are now addressed through an extensive dataset of disk images, in complement to improved simulations of the LMD-MGCM and the Mars Global Ionosphere-Thermosphere Model (MGITM) models. [less ▲]

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See detailFirst Retrieval of Thermospheric Carbon Monoxide From Mars Dayglow Observations
Evans, J. Scott; Stevens, Michael H.; Jain, Sonal et al

Conference (2017, October 01)

As a minor species in the Martian thermosphere, Carbon Monoxide (CO) is a tracer that can be used to constrain changing circulation patterns between the lower thermosphere and upper mesosphere of Mars. By ... [more ▼]

As a minor species in the Martian thermosphere, Carbon Monoxide (CO) is a tracer that can be used to constrain changing circulation patterns between the lower thermosphere and upper mesosphere of Mars. By linking CO density distributions to dynamical wind patterns, the structure and variability of the atmosphere will be better understood. Direct measurements of CO can therefore provide insight into the magnitude and pattern of winds and provide a metric for studying the response of the atmosphere to solar forcing. In addition, CO measurements can help solve outstanding photochemical modeling problems in explaining the abundance of CO at Mars. CO is directly observable by electron impact excitation and solar resonance fluorescence emissions in the far-ultraviolet (FUV). The retrieval of CO from solar fluorescence was first proposed over 40 years ago, but has been elusive at Mars due to significant spectral blending. However, by simulating the spectral shape of each contributing emission feature, electron impact excitation and solar fluorescence brightnesses can be extracted from the composite spectrum using a multiple linear regression approach. We use CO Fourth Positive Group (4PG) molecular band emission observed on the limb (130 - 200 km) by the Imaging Ultraviolet Spectrograph (IUVS) on NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft over both northern and southern hemispheres from October 2014 to December 2016. We present the first direct retrieval of CO densities by FUV remote sensing in the upper atmosphere of Mars. Atmospheric composition is inferred using the terrestrial Atmospheric Ultraviolet Radiance Integrated Code adapted to the Martian atmosphere. We investigate the sensitivity of CO density retrievals to variability in solar irradiance, solar longitude, and local time. We compare our results to predictions from the Mars Global Ionosphere-Thermosphere Model as well as in situ measurements by the Neutral Gas and Ion Mass Spectrometer on MAVEN and quantify any differences. [less ▲]

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See detailMars topographic clouds: MAVEN/IUVS observations and LMD MGCM predictions
Schneider, Nicholas M.; Connour, Kyle; Forget, Francois et al

Conference (2017, October 01)

The Imaging Ultraviolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft takes mid-UV spectral images of the Martian atmosphere. From these apoapse disk ... [more ▼]

The Imaging Ultraviolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft takes mid-UV spectral images of the Martian atmosphere. From these apoapse disk images, information about clouds and aerosols can be retrieved and comprise the only MAVEN observations of topographic clouds and cloud morphologies. Measuring local time variability of large-scale recurring cloud features is made possible with MAVEN’s ~4.5-hour elliptical orbit, something not possible with sun-synchronous orbits. We have run the LMD MGCM (Mars global circulation model) at 1° x 1° resolution to simulate water ice cloud formation with inputs consistent with observing parameters and Mars seasons. Topographic clouds are observed to form daily during the late mornings of northern hemisphere spring and this phenomenon recurs until late summer (Ls = 160°), after which topographic clouds wane in thickness. By northern fall, most topographic clouds cease to form except over Arsia Mons and Pavonis Mons, where clouds can still be observed. Our data show moderate cloud formation over these regions as late as Ls = 220°, something difficult for the model to replicate. Previous studies have shown that models have trouble simulating equatorial cloud thickness in combination with a realistic amount of water vapor and not-too-thick polar water ice clouds, implying aspects of the water cycle are not fully understood. We present data/model comparisons as well as further refinements on parameter inputs based on IUVS observations. [less ▲]

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See detailFirst Detection of the Nitric Oxide Dayglow on Mars
Stevens, Michael H.; Siskind, David E.; Evans, J. Scott et al

Conference (2017, October 01)

Nitric oxide (NO) is a well-known indicator of solar and auroral activity in the terrestrial upper atmosphere. Direct measurements of NO on Mars can therefore constrain studies of energetic processes ... [more ▼]

Nitric oxide (NO) is a well-known indicator of solar and auroral activity in the terrestrial upper atmosphere. Direct measurements of NO on Mars can therefore constrain studies of energetic processes controlling the composition and structure of its upper atmosphere (80-200 km). Identifying and quantifying these processes is one of the science objectives of NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission currently orbiting Mars. NO can be observed directly by solar resonance fluorescence in the mid-ultraviolet (MUV). Indeed, this approach has routinely been used to measure terrestrial NO for 50 years. On Mars, this “dayglow” emission is very weak relative to other bright MUV features and thus has confounded attempts at its detection there for nearly the same amount of time. Here, we report the first detection of the NO dayglow in the Martian atmosphere using limb observations by the Imaging Ultraviolet Spectrograph (IUVS) on the MAVEN spacecraft. The detection is enabled by the spectral modeling and removal of the carbon monoxide Cameron bands, which dominate the MUV limb spectra. We focus on the spectral region between 213.0-225.5 nm, where three NO gamma bands emit. We will infer NO densities from the dayglow spectra and compare our observations with predictions from a photochemical model. We will discuss the implications, particularly in the context of previous in situ measurements. [less ▲]

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See detailOptical linear polarization measurements of quasars obtained with the 3.6 m telescope at the La Silla Observatory
Hutsemekers, Damien ULiege; Hall, P.; Sluse, Dominique ULiege

in Astronomy and Astrophysics (2017), 606

We report 192 previously unpublished optical linear polarization measurements of quasars obtained in April 2003, April 2007, and October 2007 with the European Southern Observatory Faint Object ... [more ▼]

We report 192 previously unpublished optical linear polarization measurements of quasars obtained in April 2003, April 2007, and October 2007 with the European Southern Observatory Faint Object Spectrograph and Camera (EFOSC2) instrument attached to the 3.6 m telescope at the La Silla Observatory. Each quasar was observed once. Among the 192 quasars, 89 have a polarization degree p ≥ 0.6%, 18 have p ≥ 2%, and two have p ≥ 10%. Based on observations made with the ESO 3.6 m Telescope at the La Silla Observatory under program ID 071.B-0460, 079.A-0625, 080.A-0017.Full Table 4 is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A101">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A101</A> [less ▲]

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See detailIsotopic Ratios in a Peculiar Outbursting Comet
Yang, Bin; Hutsemekers, Damien ULiege; Shinnaka, Yoshiharu et al

in Bulletin of the American Astronomical Society (2017, October 01), 49

Isotopic ratios in comets provide keys for the understanding of the origin of cometary material, and the physical and chemical conditions in the early Solar Nebula. A newly discovered peculiar comet, C ... [more ▼]

Isotopic ratios in comets provide keys for the understanding of the origin of cometary material, and the physical and chemical conditions in the early Solar Nebula. A newly discovered peculiar comet, C/2015 ER61, underwent an outburst with a total brightness increase of 2 magnitudes on the night of April 4th, 2017. The sharp increase in brightness offers a rare opportunity to measure the isotopic ratios of the light elements of this comet. We obtained two high-resolution spectra of C/2015 ER61 with UVES on Apr. 13 and Apr. 17 respectively. At the time of our observations, the comet was fading gradually since the outburst. We measured the 12C/13C and 14N/15N isotopic ratios from the CN Violet (0,0) band. In addition, we determined the 14N/15N ratio in NH2 for C/2015 ER61 from four pairs of NH2 isotopologue lines. Some 18OH lines were detected but the S/N of these lines is too low to derive a reliable 18O/16O estimate. We will present our UVES spectra of C/2015 ER61, obtained shortly after the outburst. We will also present the comparison of the Isotopic ratios of C/2015 ER61 with those of other comets. [less ▲]

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See detailRAPPORT SUR L’ÉGALITÉ ENTRE LES FEMMES ET LES HOMMES À L’UNIVERSITÉ DE LIÈGE 2017 - rapport genre 2017
Cornet, Annie ULiege

E-print/Working paper (2017)

this report present the statistical data of University de Liège (student and personal) for the year 2016-2017. Similar report in 2016 and 2014.

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