References of "Magain, Pierre"      in Complete repository Arts & humanities   Archaeology   Art & art history   Classical & oriental studies   History   Languages & linguistics   Literature   Performing arts   Philosophy & ethics   Religion & theology   Multidisciplinary, general & others Business & economic sciences   Accounting & auditing   Production, distribution & supply chain management   Finance   General management & organizational theory   Human resources management   Management information systems   Marketing   Strategy & innovation   Quantitative methods in economics & management   General economics & history of economic thought   International economics   Macroeconomics & monetary economics   Microeconomics   Economic systems & public economics   Social economics   Special economic topics (health, labor, transportation…)   Multidisciplinary, general & others Engineering, computing & technology   Aerospace & aeronautics engineering   Architecture   Chemical engineering   Civil engineering   Computer science   Electrical & electronics engineering   Energy   Geological, petroleum & mining engineering   Materials science & engineering   Mechanical engineering   Multidisciplinary, general & others Human health sciences   Alternative medicine   Anesthesia & intensive care   Cardiovascular & respiratory systems   Dentistry & oral medicine   Dermatology   Endocrinology, metabolism & nutrition   Forensic medicine   Gastroenterology & hepatology   General & internal medicine   Geriatrics   Hematology   Immunology & infectious disease   Laboratory medicine & medical technology   Neurology   Oncology   Ophthalmology   Orthopedics, rehabilitation & sports medicine   Otolaryngology   Pediatrics   Pharmacy, pharmacology & toxicology   Psychiatry   Public health, health care sciences & services   Radiology, nuclear medicine & imaging   Reproductive medicine (gynecology, andrology, obstetrics)   Rheumatology   Surgery   Urology & nephrology   Multidisciplinary, general & others Law, criminology & political science   Civil law   Criminal law & procedure   Criminology   Economic & commercial law   European & international law   Judicial law   Metalaw, Roman law, history of law & comparative law   Political science, public administration & international relations   Public law   Social law   Tax law   Multidisciplinary, general & others Life sciences   Agriculture & agronomy   Anatomy (cytology, histology, embryology...) & physiology   Animal production & animal husbandry   Aquatic sciences & oceanology   Biochemistry, biophysics & molecular biology   Biotechnology   Entomology & pest control   Environmental sciences & ecology   Food science   Genetics & genetic processes   Microbiology   Phytobiology (plant sciences, forestry, mycology...)   Veterinary medicine & animal health   Zoology   Multidisciplinary, general & others Physical, chemical, mathematical & earth Sciences   Chemistry   Earth sciences & physical geography   Mathematics   Physics   Space science, astronomy & astrophysics   Multidisciplinary, general & others Social & behavioral sciences, psychology   Animal psychology, ethology & psychobiology   Anthropology   Communication & mass media   Education & instruction   Human geography & demography   Library & information sciences   Neurosciences & behavior   Regional & inter-regional studies   Social work & social policy   Sociology & social sciences   Social, industrial & organizational psychology   Theoretical & cognitive psychology   Treatment & clinical psychology   Multidisciplinary, general & others     Showing results 1 to 20 of 274 1 2 3 4 5 6     COSMOGRAIL XIX: Time delays in 18 strongly lensed quasars from 15 years of optical monitoringMillon, M.; Courbin, F.; Bonvin, V. et alin Astronomy and Astrophysics (2020), 640We present the results of 15 years of monitoring of lensed quasars conducted by the COSMOGRAIL program at the Leonhard Euler 1.2m Swiss Telescope. The decade-long light curves of 23 lensed QSOs are ... [more ▼]We present the results of 15 years of monitoring of lensed quasars conducted by the COSMOGRAIL program at the Leonhard Euler 1.2m Swiss Telescope. The decade-long light curves of 23 lensed QSOs are presented for the first time. We complement our data set with other monitoring data available in the literature to measure the time delays in 18 systems, among which 9 reach a relative precision better than 15% for at least one time delay. To achieve this, we develop an automated version of the curve-shifting toolbox PyCS to ensure robust estimation of the time delay in the presence of microlensing while accounting for the errors due to imperfect representation of microlensing. We also reanalyze the previously published time delays of RX J1131$-$1231 and HE 0435$-$1223, adding respectively 6 and 2 new seasons of monitoring and confirming the previous time-delay measurements. When the time delay measurement is possible, we correct the light curves of the lensed images from their time delay and present the difference curves to highlight the microlensing signal contained in the data. This is to date the largest sample of decade-long lens monitoring data, useful to measure $H_0$, to measure the size of quasar accretion disks with microlensing, and to study quasar variability. [less ▲]Detailed reference viewed: 42 (5 ULiège) VizieR Online Data Catalog: R-band light curves of 23 lensed QSOs (Millon+, 2020)Millon, M.; Courbin, F.; Bonvin, V. et alTextual, factual or bibliographical database (2020)Data associated with paper Millon et al. 2020, A&A 639, A101. R-band cosmograil light curves of lensed quasars taken at the Euler 1.2m Swiss telescope with the EulerCAM and EulerC2 instrument. Additional ... [more ▼]Data associated with paper Millon et al. 2020, A&A 639, A101. R-band cosmograil light curves of lensed quasars taken at the Euler 1.2m Swiss telescope with the EulerCAM and EulerC2 instrument. Additional data taken at the SMARTS 1.3m telescope with the ANDICAM optical/ infrared camera are also included for SDSS J0924+0219 (MacLeod et al., 2015ApJ...806..258M, Cat. J/ApJ/806/258).
(5 data files). [less ▲]Detailed reference viewed: 32 (3 ULiège) Cosmology with type Ia supernovae : the ultraviolet 'catastroph'? Evolution with redshift of type Ia supernovae in the ultraviolet domainHauret, Clémentine ; Magain, Pierre Poster (2018, December 07)To extract useful cosmological information from type Ia supernovae (SNe Ia), standardization laws have to be determined and applied assuming that these objects do not intrinsically change with redshift ... [more ▼]To extract useful cosmological information from type Ia supernovae (SNe Ia), standardization laws have to be determined and applied assuming that these objects do not intrinsically change with redshift. Recently, to improve that standardization, attention has been drawn towards the SNe Ia UV spectra. This resulted in (what seemed as) the discovery of two subpopulations of objects, grouped by their bluer or redder UV colors. To confirm the existence of these subpopulations, we significantly enlarged the number of studied SNe Ia (going from ~100 to ~700 objects). With such a sample, SNe Ia cannot be separated in two groups anymore but they rather follow a continuum of colors. More critically, we showed that the SNe Ia UV colors display a significant evolution with redshift, resulting in a potentially important impact on subsequent cosmological measurements. [less ▲]Detailed reference viewed: 59 (8 ULiège) A cosmology-independent calibration of type Ia supernovae dataHauret, Clémentine ; Magain, Pierre ; Biernaux, Judith in Monthly Notices of the Royal Astronomical Society (2018), 479(3), 3996-4003Recently, the common methodology used to transform type Ia supernovae (SNe Ia) into genuine standard candles has been suffering criticism. Indeed, it assumes a par- ticular cosmological model (namely the ... [more ▼]Recently, the common methodology used to transform type Ia supernovae (SNe Ia) into genuine standard candles has been suffering criticism. Indeed, it assumes a par- ticular cosmological model (namely the flat LambdaCDM) to calibrate the standardisation corrections parameters, i.e. the dependency of the supernova peak absolute magnitude on its colour, post-maximum decline rate and host galaxy mass. As a result, this as- sumption could make the data compliant to the assumed cosmology and thus nullify all works previously conducted on model comparison. In this work, we verify the viability of these hypotheses by developing a cosmology-independent approach to standardise SNe Ia data from the recent JLA compilation. Our resulting corrections turn out to be very close to the LambdaCDM-based corrections. Therefore, even if a LambdaCDM-based calibra- tion is questionable from a theoretical point of view, the potential compliance of SNe Ia data does not happen in practice for the JLA compilation. Previous works of model comparison based on these data do not have to be called into question. However, as this cosmology-independent standardisation method has the same degree of complex- ity than the model-dependent one, it is worth using it in future works, especially if smaller samples are considered, such as the superluminous type Ic supernovae. [less ▲]Detailed reference viewed: 54 (11 ULiège) High-precision multi-wavelength eclipse photometry of the ultra-hot gas giant exoplanet WASP-103 bDelrez, Laetitia ; Madhusudhan, Nikku; Lendl, Monika et alin Monthly Notices of the Royal Astronomical Society (2018), 474(2), 2334-2351We present 16 occultation and three transit light curves for the ultra-short period hot Jupiter WASP-103b, in addition to five new radial velocity measurements. We combine these observations with archival ... [more ▼]We present 16 occultation and three transit light curves for the ultra-short period hot Jupiter WASP-103b, in addition to five new radial velocity measurements. We combine these observations with archival data and perform a global analysis of the resulting extensive data set, accounting for the contamination from a nearby star. We detect the thermal emission of the planet in both the z' and KS bands, the measured occultation depths being 699±110 ppm (6.4σ) and 3567-350 +400 ppm (10.2σ), respectively. We use these two measurements, together with recently published HST/WFC3 data, to derive joint constraints on the properties of WASP- 103b's dayside atmosphere. On one hand, we find that the z' band and WFC3 data are best fit by an isothermal atmosphere at 2900K or an atmosphere with a low H2O abundance. On the other hand, we find an unexpected excess in the KS band measured flux compared to these models, which requires confirmation with additional observations before any interpretation can be given. From our global data analysis, we also derive a broad-band optical transmission spectrum that shows a minimum around 700 nm and increasing values towards both shorter and longer wavelengths. This is in agreement with a previous study based on a large fraction of the archival transit light curves used in our analysis. The unusual profile of this transmission spectrum is poorly matched by theoretical spectra and is not confirmed by more recent observations at higher spectral resolution. Additional data, in both emission and transmission, are required to better constrain the atmospheric properties of WASP-103b. © 2017 The Author(s). [less ▲]Detailed reference viewed: 40 (7 ULiège) Cosmological Time, Entropy and InfinityHauret, Clémentine ; Magain, Pierre ; Biernaux, Judith in Entropy (2017), 19(7), Time is a parameter playing a central role in our most fundamental modelling of natural laws. Relativity theory shows that the comparison of times measured by different clocks depends on their relative ... [more ▼]Time is a parameter playing a central role in our most fundamental modelling of natural laws. Relativity theory shows that the comparison of times measured by different clocks depends on their relative motion and on the strength of the gravitational field in which they are embedded. In standard cosmology, the time parameter is the one measured by fundamental clocks (i.e., clocks at rest with respect to the expanding space). This proper time is assumed to flow at a constant rate throughout the whole history of the universe. We make the alternative hypothesis that the rate at which the cosmological time flows depends on the dynamical state of the universe. In thermodynamics, the arrow of time is strongly related to the second law, which states that the entropy of an isolated system will always increase with time or, at best, stay constant. Hence, we assume that the time measured by fundamental clocks is proportional to the entropy of the region of the universe that is causally connected to them. Under that simple assumption, we find it possible to build toy cosmological models that present an acceleration of their expansion without any need for dark energy while being spatially closed and finite, avoiding the need to deal with infinite values. [less ▲]Detailed reference viewed: 74 (18 ULiège) A seven-planet resonant chain in TRAPPIST-1Luger, Rodrigo; Sestovic, Marko; Kruse, Ethan et alin Nature Astronomy (2017), 1The TRAPPIST-1 system is the first transiting planet system found orbiting an ultracool dwarf star[SUP] 1 [/SUP]. At least seven planets similar in radius to Earth were previously found to transit this ... [more ▼]The TRAPPIST-1 system is the first transiting planet system found orbiting an ultracool dwarf star[SUP] 1 [/SUP]. At least seven planets similar in radius to Earth were previously found to transit this host star[SUP] 2 [/SUP]. Subsequently, TRAPPIST-1 was observed as part of the K2 mission and, with these new data, we report the measurement of an 18.77 day orbital period for the outermost transiting planet, TRAPPIST-1 h, which was previously unconstrained. This value matches our theoretical expectations based on Laplace relations[SUP] 3 [/SUP] and places TRAPPIST-1 h as the seventh member of a complex chain, with three-body resonances linking every member. We find that TRAPPIST-1 h has a radius of 0.752 R [SUB]⊕[/SUB] and an equilibrium temperature of 173 K. We have also measured the rotational period of the star to be 3.3 days and detected a number of flares consistent with a low-activity, middle-aged, late M dwarf. [less ▲]Detailed reference viewed: 179 (15 ULiège) Seven temperate terrestrial planets around the nearby ultracool dwarf starGillon, Michaël ; Triaud, Amaury; Demory, Brice-Olivier et alin Nature (2017), 542One focus of modern astronomy is to detect temperate terrestrial exoplanets well-suited for atmospheric characterisation. A milestone was recently achieved with the detection of three Earth-sized planets ... [more ▼]One focus of modern astronomy is to detect temperate terrestrial exoplanets well-suited for atmospheric characterisation. A milestone was recently achieved with the detection of three Earth-sized planets transiting (i.e. passing in front of) a star just 8% the mass of the Sun 12 parsecs away. Indeed, the transiting configuration of these planets combined with the Jupiter-like size of their host star - named TRAPPIST-1 - makes possible indepth studies of their atmospheric properties with current and future astronomical facilities. Here we report the results of an intensive photometric monitoring campaign of that star from the ground and with the Spitzer Space Telescope. Our observations reveal that at least seven planets with sizes and masses similar to the Earth revolve around TRAPPIST-1. The six inner planets form a near-resonant chain such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.21, 12.35 days) are near ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inward. The seven planets have equilibrium temperatures low enough to make possible liquid water on their surfaces. [less ▲]Detailed reference viewed: 313 (53 ULiège) Analysis of luminosity distributions of strong lensing galaxies: subtraction of diffuse lensed signalBiernaux, Judith ; Magain, Pierre ; Hauret, Clémentine in Astronomy and Astrophysics (2017)Detailed reference viewed: 33 (8 ULiège) Temperate Earth-sized planets transiting a nearby ultracool dwarf starGillon, Michaël ; Jehin, Emmanuel ; Lederer, Susan M. et alin Nature (2016), 533Star-like objects with effective temperatures of less than 2,700 kelvin are referred to as ‘ultracool dwarfs’. This heterogeneous group includes stars of extremely low mass as well as brown dwarfs ... [more ▼]Star-like objects with effective temperatures of less than 2,700 kelvin are referred to as ‘ultracool dwarfs’. This heterogeneous group includes stars of extremely low mass as well as brown dwarfs (substellar objects not massive enough to sustain hydrogen fusion), and represents about 15 per cent of the population of astronomical objects near the Sun. Core-accretion theory predicts that, given the small masses of these ultracool dwarfs, and the small sizes of their protoplanetary disks, there should be a large but hitherto undetected population of terrestrial planets orbiting them—ranging from metal-rich Mercury-sized planets to more hospitable volatile-rich Earth-sized planets. Here we report observations of three short-period Earth-sized planets transiting an ultracool dwarf star only 12 parsecs away. The inner two planets receive four times and two times the irradiation of Earth, respectively, placing them close to the inner edge of the habitable zone of the star. Our data suggest that 11 orbits remain possible for the third planet, the most likely resulting in irradiation significantly less than that received by Earth. The infrared brightness of the host star, combined with its Jupiter-like size, offers the possibility of thoroughly characterizing the components of this nearby planetary system. [less ▲]Detailed reference viewed: 96 (14 ULiège) Analysis of luminosity distributions and shape parameters of strong gravitational lensing elliptical galaxiesBiernaux, Judith ; Magain, Pierre ; Sluse, Dominique et alin Astronomy and Astrophysics (2016), 585Context. The luminosity profiles of galaxies acting as strong gravitational lenses can be tricky to study. Indeed, strong gravitational lensing images display several lensed components, both point-like ... [more ▼]Context. The luminosity profiles of galaxies acting as strong gravitational lenses can be tricky to study. Indeed, strong gravitational lensing images display several lensed components, both point-like and diffuse, around the lensing galaxy. Those objects restrain the study of the galaxy luminosity to its inner parts. Therefore, the usual fitting methods perform rather badly on such images. Previous studies of strong lenses luminosity profiles using such codes and various PSF-determining methods have resulted in somewhat discrepant results. Aims. The present work aims at investigating the causes of those discrepancies, as well as at designing more robust techniques to study the morphology of early-type lensing galaxies, with the ability to subtract lensed signal from their luminosity profiles. Methods. Each shape parameter, namely, the position angle, ellipticity and half-light radius of the galaxy, are determined as independently from each other as possible. The half-light radius measurement method is based on the computation of isophotes. Its robustness regarding various specific aspects of gravitational lensing image processing is analysed and tested versus that of a widely used fitting code, GALFIT. Those techniques are then applied on a sample of systems from the CASTLES database. Results. Simulations show that, when restricted to small, inner parts of the lensing galaxy, the technique presented here is more robust than GALFIT. It gives unbiased results, while GALFIT leads to an overestimation of the half-light radius that can reach about 10%, depending, among others, on the SNR. It is therefore better-suited than GALFIT for gravitational lensing images. It is also able to study lensing galaxies that are not much larger than the PSF, as opposed to GALFIT. New values for the half-light radius of the objects in our sample are presented and compared to previous works. [less ▲]Detailed reference viewed: 53 (21 ULiège) Long-term activity and outburst of comet C/2013 A1 (Siding Spring) from narrow-band photometry and long-slit spectroscopyOpitom, Cyrielle ; Guilbert-Lepoutre, A.; Jehin, Emmanuel et alin Astronomy and Astrophysics (2016), 589In this paper, we present a unique data set of more than one year's worth of regular observations of comet C/2013 A1(Siding Spring) with TRAPPIST in Chile, along with low-resolution spectra obtained with ... [more ▼]In this paper, we present a unique data set of more than one year's worth of regular observations of comet C/2013 A1(Siding Spring) with TRAPPIST in Chile, along with low-resolution spectra obtained with the ESO/VLT FORS 2 instrument. The comet made a close approach to Mars on October 19, 2014 and was then observed by many space and ground-based telescopes. We followed the evolution of the OH, NH, CN, $\mathrm{C_3}$, and $\mathrm{C_2}$ production rates as well as the $Af\rho$ parameter as a proxy for the dust production. We detected an outburst two weeks after perihelion, with gas and dust production rates being multiplied by a factor five within a few days. By modelling the shape of the CN and $\mathrm{C_2}$ radial profiles, we determined that the outburst happened around on November 10 around 15:30 UT ($\pm$ 5h) and measured a gas ejection velocity of $1.1\pm0.2$ km/s. We used a thermal evolution model to reproduce the activity pattern and outburst. Our results are consistent with the progressive formation of a dust mantle explaining the shallow dependence of gas production rates, which may be partially blown off during the outburst. We studied the evolution of gas composition, using various ratios such as CN/OH, $\mathrm{C_2}$/OH, or $\mathrm{C_3}$/OH, which showed little or no variation with heliocentric distance including at the time of the outburst. This indicates a relative level of homogeneity of the nucleus composition. [less ▲]Detailed reference viewed: 51 (13 ULiège) TRAPPIST photometry and imaging monitoring of comet C/2013 R1 (Lovejoy): Implications for the origin of daughter speciesOpitom, Cyrielle ; Jehin, Emmanuel ; Manfroid, Jean et alin Astronomy and Astrophysics (2015), 584We report the results of the narrow-band photometry and imaging monitoring of comet C/2013 R1 (Lovejoy) with the robotic telescope TRAPPIST (La Silla observatory). We gathered around 400 images over 8 ... [more ▼]We report the results of the narrow-band photometry and imaging monitoring of comet C/2013 R1 (Lovejoy) with the robotic telescope TRAPPIST (La Silla observatory). We gathered around 400 images over 8 months pre- and post-perihelion between September 12, 2013 and July 6, 2014. We followed the evolution of the OH, NH, CN, C[SUB]3[/SUB], and C[SUB]2[/SUB] production rates computed with the Haser model, as well as the evolution of the dust production. All five gas species display an asymmetry about perihelion, since the rate of brightening is steeper than the rate of fading. The study of the coma morphology reveals gas and dust jets that indicate one or several active zone(s) on the nucleus. The dust, C[SUB]2[/SUB], and C[SUB]3[/SUB] morphologies present some similarities, while the CN morphology is different. OH and NH are enhanced in the tail direction. The study of the evolution of the comet activity shows that the OH, NH, and C[SUB]2[/SUB] production rate evolution with the heliocentric distance is correlated to the dust evolution. The CN and, to a lesser extent, the C[SUB]3[/SUB] do not display such a correlation with the dust. This evidence and the comparison with parent species production rates indicate that C[SUB]2[/SUB] and C[SUB]3[/SUB], on one hand, and OH and NH, on the other, could be - at least partially - released from organic - rich grains and icy grains. On the contrary, all evidences point to HCN being the main parent of CN in this comet. [less ▲]Detailed reference viewed: 66 (14 ULiège) Five years of comet narrow band photometry and imaging with TRAPPISTOpitom, Cyrielle ; Jehin, Emmanuel ; Manfroid, Jean et alin Bulletin of the American Astronomical Society (2015, November 01), 47TRAPPIST is a 60-cm robotic telescope in La Silla Observatory [1] mainly dedicated to the study of exoplanets and comets. The telescope is equipped with a set of narrow band cometary filters designed by ... [more ▼]TRAPPIST is a 60-cm robotic telescope in La Silla Observatory [1] mainly dedicated to the study of exoplanets and comets. The telescope is equipped with a set of narrow band cometary filters designed by the NASA for the Hale-Bopp observing campaign [2]. Since its installation in 2010, we gathered a high quality and homogeneous data set of more than 30 bright comets observed with narrow band filters. Some comets were only observed for a few days but others have been observed weekly during several months on both sides of perihelion. From the images, we derived OH, NH, CN, C[SUB]2[/SUB], and C[SUB]3[/SUB] production rates using a Haser [3] model in addition to the Afρ parameter as a proxy for the dust production. We computed production rates ratios and the dust color for each comet to study their composition and followed the evolution of these ratios and colors with the heliocentric distance.The TRAPPIST data set, rich of more than 10000 images obtained and reduced in an homogeneous way, allows us to address several fundamental questions such as the pristine or evolutionary origin of composition differences among comets. The evolution of comet activity with the heliocentric distance, the differences between species, and from comet to comet, will be discussed. Finally, the first results about the one year campaign on comet C/2013 US10 (Catalina) and our recent work on the re-determination of Haser scalelengths will be presented.[1] Jehin et al., The Messenger, 145, 2-6, 2011[2] Farnham et al., Icarus, 147, 180-204, 2000[3] Haser, Bulletin de l’Académie Royal des Sciences de Belgique,63, 739, 1957 [less ▲]Detailed reference viewed: 40 (8 ULiège) VizieR Online Data Catalog: Shape parameters of lensing galaxies (Biernaux+, 2016)Biernaux, Judith ; Magain, Pierre ; Sluse, Dominique et alTextual, factual or bibliographical database (2015)In the paper we explain procedures designed to measure the position angle, the ellipticity and the half-light radius of lensing galaxies, that rely on an innovative scheme to compute isophotes. Table 6 ... [more ▼]In the paper we explain procedures designed to measure the position angle, the ellipticity and the half-light radius of lensing galaxies, that rely on an innovative scheme to compute isophotes. Table 6 details frame per frame the characteristics of the masks used in this work. Those values are in fact the shape parameters of the galaxies, before correcting from the effect of the PSF. The relative coordinates of the galaxy center, with regards to a reference lensed image, and the size of the region of interest are given as well. The reference lensed image can be found in Fig. 2 in the paper and is the one labelled A (or A1 in some cases).