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 Références de "Scuflaire, Richard"      dans Tout le dépôt Arts & sciences humaines   Archéologie   Art & histoire de l'art   Arts du spectacle   Etudes classiques & orientales   Histoire   Langues & linguistique   Littérature   Philosophie & éthique   Religion & théologie   Multidisciplinaire, généralités & autres Droit, criminologie & sciences politiques   Criminologie   Droit civil   Droit économique & commercial   Droit européen & international   Droit fiscal   Droit judiciaire   Droit pénal & procédure pénale   Droit public   Droit social   Métadroit, droit romain, histoire du droit & droit comparé   Sciences politiques, administration publique & relations internationales   Multidisciplinaire, généralités & autres Ingénierie, informatique & technologie   Architecture   Energie   Géologie, ingénierie du pétrole & des mines   Ingénierie aérospatiale   Ingénierie chimique   Ingénierie civile   Ingénierie électrique & électronique   Ingénierie mécanique   Science des matériaux & ingénierie   Sciences informatiques   Multidisciplinaire, généralités & autres Physique, chimie, mathématiques & sciences de la terre   Aérospatiale, astronomie & astrophysique   Chimie   Mathématiques   Physique   Sciences de la terre & géographie physique   Multidisciplinaire, général & autres Sciences de la santé humaine   Anesthésie & soins intensifs   Chirurgie   Dentisterie & médecine buccale   Dermatologie   Endocrinologie, métabolisme & nutrition   Gastroentérologie & hépatologie   Gériatrie   Hématologie   Immunologie & maladie infectieuse   Médecine de la reproduction (Gynécologie, andrologie, obstétrique)   Médecine de laboratoire & technologie médicale   Médecine générale & interne   Médecine légale   Médecine non conventionnelle   Neurologie   Oncologie   Ophtalmologie   Orthopédie, rééducation & médecine sportive   Oto-rhino-laryngologie   Pédiatrie   Pharmacie, pharmacologie & toxicologie   Psychiatrie   Radiologie, imagerie médicale et médecine nucléaire   Rhumatologie   Santé publique, services médicaux & soins de santé   Systèmes cardiovasculaire & respiratoire   Urologie & néphrologie   Multidisciplinaire, généralités & autres Sciences du vivant   Agriculture & agronomie   Anatomie (cytologie, histologie, embryologie...) & physiologie   Biochimie, biophysique & biologie moléculaire   Biologie végétale (sciences végétales, sylviculture, mycologie...)   Biotechnologie   Entomologie & lutte antiravageur   Génétique & processus génétiques   Médecine vétérinaire & santé animale   Microbiologie   Productions animales & zootechnie   Sciences aquatiques & océanologie   Sciences de l'environnement & écologie   Sciences des denrées alimentaires   Zoologie   Multidisciplinaire, généralités & autres Sciences économiques & de gestion   Comptabilité & audit   Production, distribution & gestion de la chaîne logistique   Finance   Gestion de l'entreprise & théorie des organisations   Gestion des ressources humaines   Gestion des systèmes d'information   Marketing   Stratégie & innovation   Méthodes quantitatives en économie & gestion   Economie générale & histoire de la pensée économique   Economie internationale   Macroéconomie & économie monétaire   Microéconomie   Systèmes économiques & économie publique   Economie sociale   Domaines particuliers de l'économie (santé, travail, transport…)   Multidisciplinaire, généralités & autres Sciences sociales & comportementales, psychologie   Anthropologie   Bibliothéconomie & sciences de l’information   Communication & médias   Education & enseignement   Etudes régionales & interrégionales   Geographie humaine & démographie   Neurosciences & comportement   Psychologie animale, éthologie & psychobiologie   Psychologie cognitive & théorique   Psychologie sociale, industrielle & organisationnelle   Sociologie & sciences sociales   Traitement & psychologie clinique   Travail social & politique sociale   Multidisciplinaire, généralités & autres     Résultats 1 à 20 sur un total de 68 1 2 3 4     Stellar parameters for TRAPPIST-1Van Grootel, Valérie ; Silva Fernandes, Catarina ; Gillon, Michaël et alin Astrophysical Journal (2018), 853TRAPPIST-1 is an ultracool dwarf star transited by seven Earth-sized planets, for which thorough characterization of atmospheric properties, surface conditions encompassing habitability and internal ... [plus ▼]TRAPPIST-1 is an ultracool dwarf star transited by seven Earth-sized planets, for which thorough characterization of atmospheric properties, surface conditions encompassing habitability and internal compositions is possible with current and next generation telescopes. Accurate modeling of the star is essential to achieve this goal. We aim to obtain updated stellar parameters for TRAPPIST- 1 based on new measurements and evolutionary models, compared to those used in discovery studies. We present a new measurement for the parallax of TRAPPIST-1, 82.4 $\pm$ 0.8 mas, based on 188 epochs of observations with the TRAPPIST and Liverpool Telescopes from 2013 to 2016. This revised parallax yields an updated luminosity of $L_*=(5.22\pm0.19)\times 10^{-4} L_{\odot}$, very close to the previous estimate but almost twice more precise. We next present an updated estimate for TRAPPIST-1 stellar mass, based on two approaches: mass from stellar evolution modeling, and empirical mass derived from dynamical masses of equivalently classified ultracool dwarfs in astrometric binaries. We combine them through a Monte-Carlo approach to derive a semi-empirical estimate for the mass of TRAPPIST-1. We also derive estimate for the radius by combining this mass with stellar density inferred from transits, as well as estimate for the effective temperature from our revised luminosity and radius. Our final results are $M_*=0.089 \pm 0.006 M_{\odot}$, $R_* = 0.121 \pm 0.003 R_{\odot}$, and $T_{\rm eff} =$ 2516 $\pm$ 41 K. Considering the degree to which TRAPPIST-1 system will be scrutinized in coming years, these revised and more precise stellar parameters should be considered when assessing the properties of TRAPPIST-1 planets. [moins ▲]Visualisation de la référence détaillée: 66 (3 ULiège) Seismic inversion of the solar entropy. A case for improving the standard solar modelBuldgen, Gaël ; Salmon, Sébastien ; Noels-Grötsch, Arlette et alin Astronomy and Astrophysics (2017), 607Context. The Sun is the most constrained and well-studied of all stars. As a consequence, the physical ingredients entering solar models are used as a reference to study all other stars observed in the ... [plus ▼]Context. The Sun is the most constrained and well-studied of all stars. As a consequence, the physical ingredients entering solar models are used as a reference to study all other stars observed in the Universe. However, our understanding of the solar structure is still imperfect, as illustrated by the current debate on the heavy element abundances in the Sun.
Aims: We provide additional information on the solar structure by carrying out structural inversions of a new physical quantity, a proxy of the entropy of the solar plasma whose properties are very sensitive to the temperature gradient below the convective zone.
Methods: We use new structural kernels to carry out direct inversions of an entropy proxy of the solar plasma and compare the solar structure to various standard solar models built using various opacity tables and chemical abundances. We also link our results to classical tests commonly found in the literature.
Results: Our analysis allows us to probe more efficiently the uncertain regions of the solar models, just below the convective zone, paving the way for new in-depth analyses of the Sun taking into account additional physical uncertainties of solar models beyond the specific question of chemical abundances. [moins ▲]Visualisation de la référence détaillée: 20 (3 ULiège) Determining the metallicity of the solar envelope using seismic inversion techniquesBuldgen, Gaël ; Salmon, Sébastien ; Noels-Grötsch, Arlette et alin Monthly Notices of the Royal Astronomical Society (2017), 472(1), 751-764The solar metallicity issue is a long-lasting problem of astrophysics, impacting multi- ple fields and still subject to debate and uncertainties. While spectroscopy has mostly been used to determine the ... [plus ▼]The solar metallicity issue is a long-lasting problem of astrophysics, impacting multi- ple fields and still subject to debate and uncertainties. While spectroscopy has mostly been used to determine the solar heavy elements abundance, helioseismologists at- tempted providing a seismic determination of the metallicity in the solar convective enveloppe. However, the puzzle remains since two independent groups prodived two radically different values for this crucial astrophysical parameter. We aim at provid- ing an independent seismic measurement of the solar metallicity in the convective enveloppe. Our main goal is to help provide new information to break the current stalemate amongst seismic determinations of the solar heavy element abundance. We start by presenting the kernels, the inversion technique and the target function of the inversion we have developed. We then test our approach in multiple hare-and-hounds exercises to assess its reliability and accuracy. We then apply our technique to solar data using calibrated solar models and determine an interval of seismic measurements for the solar metallicity. We show that our inversion can indeed be used to estimate the solar metallicity thanks to our hare-and-hounds exercises. However, we also show that further dependencies in the physical ingredients of solar models lead to a low accuracy. Nevertheless, using various physical ingredients for our solar models, we determine metallicity values between 0.008 and 0.014. [moins ▲]Visualisation de la référence détaillée: 27 (6 ULiège) Inversions of the Ledoux discriminant: a closer look at the tachoclineBuldgen, Gaël ; Salmon, Sébastien ; Godart, Mélanie et alin Monthly Notices of the Royal Astronomical Society : Letters (2017), 472(1), 70-74Modelling the base of the solar convective envelope is a tedious problem. Since the first rotation inversions, solar modellers are confronted with the fact that a region of very limited extent has an ... [plus ▼]Modelling the base of the solar convective envelope is a tedious problem. Since the first rotation inversions, solar modellers are confronted with the fact that a region of very limited extent has an enormous physical impact on the Sun. Indeed, it is the transition region from differential to solid body rotation, the tachocline, which furthermore is influenced by turbulence and is also supposed to be the seat of the solar magnetic dynamo. Moreover, solar models show significant disagreement with the sound speed profile in this region. In this paper, we show how helioseismology can provide further constraints on this region by carrying out an inversion of the Ledoux discriminant. We compare these inversions for Standard Solar Models built using various opacity tables and chemical abundances and discuss the origins of the discrepancies between Solar Models and the Sun. [moins ▲]Visualisation de la référence détaillée: 28 (8 ULiège) Transit confirmation and improved stellar and planet parameters for the super-Earth HD 97658 b and its host starVan Grootel, Valérie ; Gillon, Michaël ; Valencia, D. et alin Astrophysical Journal (2014), 786Super-Earths transiting nearby bright stars are key objects that simultaneously allow for accurate measurements of both their mass and radius, providing essential constraints on their internal composition ... [plus ▼]Super-Earths transiting nearby bright stars are key objects that simultaneously allow for accurate measurements of both their mass and radius, providing essential constraints on their internal composition. We present here the confirmation, based on Spitzer transit observations, that the super-Earth HD 97658 b transits its host star. HD 97658 is a low-mass ($M_*=0.77\pm0.05\,M_{\odot}$) K1 dwarf, as determined from the Hipparcos parallax and stellar evolution modeling. To constrain the planet parameters, we carry out Bayesian global analyses of Keck-HIRES radial velocities, and MOST and Spitzer photometry. HD 97658 b is a massive ($M_P=7.55^{+0.83}_{-0.79} M_{\oplus}$) and large ($R_{P} = 2.247^{+0.098}_{-0.095} R_{\oplus}$ at 4.5 $\mu$m) super-Earth. We investigate the possible internal compositions for HD 97658 b. Our results indicate a large rocky component, by at least 60% by mass, and very little H-He components, at most 2% by mass. We also discuss how future asteroseismic observations can improve the knowledge of the HD 97658 system, in particular by constraining its age. Orbiting a bright host star, HD 97658 b will be a key target for coming space missions TESS, CHEOPS, PLATO, and also JWST, to characterize thoroughly its structure and atmosphere. [moins ▲]Visualisation de la référence détaillée: 61 (13 ULiège) HD 97658 and its super-Earth: Spitzer transit analysis and seismic modeling of the host starVan Grootel, Valérie ; Gillon, Michaël ; Valencia, Diana et alCommunication orale (2013, December)Visualisation de la référence détaillée: 15 (0 ULiège) Testing Convective-core Overshooting Using Period Spacings of Dipole Modes in Red GiantsMontalbán, J.; Miglio, A.; Noels-Grötsch, Arlette et alin Astrophysical Journal (2013), 766Uncertainties on central mixing in main-sequence (MS) and core He-burning (He-B) phases affect key predictions of stellar evolution such as late evolutionary phases, chemical enrichment, ages, etc. We ... [plus ▼]Uncertainties on central mixing in main-sequence (MS) and core He-burning (He-B) phases affect key predictions of stellar evolution such as late evolutionary phases, chemical enrichment, ages, etc. We propose a test of the extension of extra-mixing in two relevant evolutionary phases based on period spacing (ΔP) of solar-like oscillating giants. From stellar models and their corresponding adiabatic frequencies (respectively, computed with ATON and LOSC codes), we provide the first predictions of the observable ΔP for stars in the red giant branch and in the red clump (RC). We find (1) a clear correlation between ΔP and the mass of the helium core (M [SUB]He[/SUB]); the latter in intermediate-mass stars depends on the MS overshooting, and hence it can be used to set constraints on extra-mixing during MS when coupled with chemical composition; and (2) a linear dependence of the average value of the asymptotic period spacing (langΔPrang[SUB] a [/SUB]) on the size of the convective core during the He-B phase. A first comparison with the inferred asymptotic period spacing for Kepler RC stars also suggests the need for extra-mixing during this phase, as evinced from other observational facts. [moins ▲]Visualisation de la référence détaillée: 15 (0 ULiège) Towards Precise Asteroseismology of Solar-Like StarsGrigahcène, A.; Dupret, Marc-Antoine ; Sousa, S. G. et alin Astrophysics and Space Science Proceedings series (2013), 31Adiabatic modeling of solar-like oscillations cannot exceed a certain level of precision for fitting individual frequencies. This is known as the problem of near-surface effects on the mode physics. We ... [plus ▼]Adiabatic modeling of solar-like oscillations cannot exceed a certain level of precision for fitting individual frequencies. This is known as the problem of near-surface effects on the mode physics. We present a theoretical study which addresses the problem of frequency precision in non-adiabatic models using a time-dependent convection treatment. We find that the number of acceptable model solutions is significantly reduced and more precise constraints can be imposed on the models. Results obtained for a specific star (β Hydri) lead to very good agreement with both global and local seismic observables. This indicates that the accuracy of model fitting to seismic data is greatly improved when a more complete description of the interaction between convection and pulsation is taken into account. [moins ▲]Visualisation de la référence détaillée: 9 (0 ULiège) Successful Asteroseismology for a Better Characterization of the Exoplanet HAT-P-7bOshagh, M.; Grigahcène, A.; Benomar, O. et alin Astrophysics and Space Science Proceedings (2013), 31It is well known that asteroseismology is the unique technique permitting the study of the internal structure of pulsating stars using their pulsational frequencies, which is per se very important. It ... [plus ▼]It is well known that asteroseismology is the unique technique permitting the study of the internal structure of pulsating stars using their pulsational frequencies, which is per se very important. It acquires an additional value when the star turns out to be a planet host. In this case, the asteroseismic study output may be a very important input for the study of the planetary system. With this in mind, we use the large time-span of the Kepler public data obtained for the star system HAT-P-7, first to perform an asteroseismic study of the pulsating star using Time-Dependent-Convection (TDC) models. Secondly, we make a revision of the planet properties in the light of the asteroseismic study. [moins ▲]Visualisation de la référence détaillée: 12 (2 ULiège) Towards an effective asteroseismology of solar-like stars: time-dependent convection effects on pulsation frequenciesGrigahcène, A.; Dupret, Marc-Antoine ; Sousa, S. G. et alin Monthly Notices of the Royal Astronomical Society (2012), 422Since the early days of helioseismology, adiabatic models have shown their limits for a precise fitting of individual oscillation frequencies. This discrepancy, which also exists for solar-type stars, is ... [plus ▼]Since the early days of helioseismology, adiabatic models have shown their limits for a precise fitting of individual oscillation frequencies. This discrepancy, which also exists for solar-type stars, is known to originate near the surface superadiabatic convective region where the interaction between oscillations and convection is likely to have a large effect on the frequencies. We present an asteroseismic study to address the adequacy of time-dependent convection (TDC) non-adiabatic models to better reproduce the observed individual frequencies. We select, for this purpose, three solar-like stars, in addition to the Sun, to which we fit the observed frequencies in a grid of TDC non-adiabatic models. The best model selection is done by applying a maximum likelihood method. The results are compared to pure adiabatic and near-surface corrected adiabatic models. We show that, first, TDC models give very good agreement for the mode frequencies and average lifetimes. In the solar case, the frequency discrepancy is reduced to <1.75 μHz over 95 per cent of the modes considered. Secondly, TDC models give an asteroseismic insight into the usually unconstrained ad hoc stellar parameters, such as the mixing-length parameter α[SUB]MLT[/SUB]. [moins ▲]Visualisation de la référence détaillée: 19 (3 ULiège) Adiabatic Solar-Like Oscillations in Red Giant StarsMontalban Iglesias, Josefa ; Miglio, Andrea; Noels-Grötsch, Arlette et alin Red Giants as Probes of the Structure and Evolution of the Milky Way (2012)Since the detection of non-radial solar-like oscillation modes in red giants with the CoRoT satellite, the interest in the asteroseismic properties of red giants and the link with their global properties ... [plus ▼]Since the detection of non-radial solar-like oscillation modes in red giants with the CoRoT satellite, the interest in the asteroseismic properties of red giants and the link with their global properties and internal structure is substantially increasing. Moreover, more and more precise data are being collected with the space-based telescopes CoRoT and Kepler. In this paper we present a survey of the most relevant theoretical and observational results obtained up to now concerning the potential of solar-like oscillations in red giants. [moins ▲]Visualisation de la référence détaillée: 18 (0 ULiège) Inference from adiabatic analysis of solar-like oscillations in red giantsMontalban Iglesias, Josefa ; Miglio, Andrea ; Noels-Grötsch, Arlette et alin Astronomische Nachrichten (2010), 331The clear detection with CoRoT and Kepler of radial and non-radial solar-like oscillations in many red giants paves the way to seismic inferences on the structure of such stars. We present an overview of ... [plus ▼]The clear detection with CoRoT and Kepler of radial and non-radial solar-like oscillations in many red giants paves the way to seismic inferences on the structure of such stars. We present an overview of the properties of the adiabatic frequencies and frequency separations of radial and non-radial oscillation modes, highlighting how their detection allows a deeper insight into the properties of the internal structure of red giants. In our study we consider models of red giants in different evolutionary stages, as well as of different masses and chemical composition. We describe how the large and small separations computed with radial modes and with non-radial modes mostly trapped in the envelope depend on the stellar global parameters and evolutionary state, and we compare our theoretical predictions and first Kepler data.Finally, we find that the properties of dipole modes constitute a promising seismic diagnostic of the evolutionary state of red-giant stars. [moins ▲]Visualisation de la référence détaillée: 27 (4 ULiège) Seismic Diagnostics of Red Giants: First Comparison with Stellar ModelsMontalban Iglesias, Josefa ; Miglio, Andrea ; Noels-Grötsch, Arlette et alin Astrophysical Journal Letters (2010), 721The clear detection with CoRoT and KEPLER of radial and non-radial solar-like oscillations in many red giants paves the way for seismic inferences on the structure of such stars. We present an overview of ... [plus ▼]The clear detection with CoRoT and KEPLER of radial and non-radial solar-like oscillations in many red giants paves the way for seismic inferences on the structure of such stars. We present an overview of the properties of the adiabatic frequencies and frequency separations of radial and non-radial oscillation modes for an extended grid of models. We highlight how their detection allows a deeper insight into the internal structure and evolutionary state of red giants. In particular, we find that the properties of dipole modes constitute a promising seismic diagnostic tool of the evolutionary state of red giant stars. We compare our theoretical predictions with the first 34 days of KEPLER data and predict the frequency diagram expected for red giants in the CoRoT exofield in the galactic center direction. [moins ▲]Visualisation de la référence détaillée: 26 (4 ULiège) Evidence for a sharp structure variation inside a red-giant starMiglio, Andrea ; Montalban Iglesias, Josefa ; Carrier, F. et alin Astronomy and Astrophysics (2010), 520Context. The availability of precisely determined frequencies of radial and non-radial oscillation modes in red giants is finally paving the way for detailed studies of the internal structure of these ... [plus ▼]Context. The availability of precisely determined frequencies of radial and non-radial oscillation modes in red giants is finally paving the way for detailed studies of the internal structure of these stars.
Aims: We look for the seismic signature of regions of sharp structure variation in the internal structure of the CoRoT target HR 7349.
Methods: We analyse the frequency dependence of the large frequency separation and second frequency differences, as well as the behaviour of the large frequency separation obtained with the envelope auto-correlation function.