Results for "S. Mathis"

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The effects of rotation on wave-induced transport in stars: the case of an intermediate-mass starJan 21 2019Internal gravity waves propagate in stellar radiative zones and transport angular momentum throughout the evolution of stars, shaping the internal rotation pro le of these regions. We use the analytical study of Andre\'e et al. (2018) to assess the impact ... More
The variation of the tidal quality factor of convective envelopes of rotating low-mass stars along their evolutionNov 03 2015More than 1500 exoplanets have been discovered around a large diversity of host stars (from M- to A-type stars). Tidal dissipation in their convective envelope is a key actor that shapes the orbital architecture of short-period systems and that still ... More
Melting the core of giant planets: impact on tidal dissipationOct 19 2015Giant planets are believed to host central dense rocky/icy cores that are key actors in the core-accretion scenario for their formation. In the same time, some of their components are unstable in the temperature and pressure regimes of central regions ... More
Towards a better understanding of tidal dissipation at corotation layers in differentially rotating stars and planetsOct 24 2017Star-planet tidal interactions play a significant role in the dynamical evolution of close-in planetary systems. We investigate the propagation and dissipation of tidal inertial waves in a stellar/planetary convective region. We take into account a latitudinal ... More
The variation of tidal dissipation in the convective envelope of low-mass stars along their evolutionJul 01 2015Since 1995, more than 1500 exoplanets have been discovered around a large diversity of host stars (from M- to A-type stars). Tidal dissipation in stellar convective envelopes is a key actor that shapes the orbital architecture of short-period systems. ... More
Making a Be star: the role of rotation and pulsationsNov 10 2013The Be phenomenon, i.e. the ejection of matter from Be stars into a circumstellar disk, has been a long lasting mystery. In the last few years, the CoRoT satellite brought clear evidence that Be outbursts are directly correlated to pulsations and rapid ... More
Observations of tides and circularization in red-giant binaries from Kepler photometryFeb 12 2019Binary stars are places of complex stellar interactions. While all binaries are in principle converging towards a state of circularization, many eccentric systems are found even in advanced stellar phases. In this work we discuss the sample of binaries ... More
Period spacings of gravity modes in rapidly rotating magnetic stars I. Axisymmetric fossil field with poloidal and toroidal componentsMar 13 2019Context. Stellar magnetic fields are one of the candidates often invoked to explain the missing transport of angular momentum observed in the models of stellar interiors. However, the properties of an internal magnetic field and the consequences of its ... More
The Warm Ionized Medium in the Milky Way and Other GalaxiesOct 10 2000Observations of the "Warm Ionized Medium" (or, equivalently, the "Diffuse Ionized Gas") of the local ISM, the Perseus arm in the Milky Way, and also in several other galaxies show strong [NII]6563 (~H-alpha in some cases) and [SII]6717/[NII]6583 = 0.6 ... More
Large-Scale Magnetic Fields in Stellar Interiors I. Equilibrium Configurations to Model Fossil FieldsApr 09 2009Mar 15 2010Context. The understanding of fossil fields origin, topology and stability is one of the corner stones of the stellar magnetism theory. On one hand, since they survive over secular time-scales, they may modify the structure and the evolution of their ... More
Thermal Recovery of Multi-Limbed Robots with Electric ActuatorsFeb 01 2019Feb 04 2019The problem of finding thermally minimizing configurations of a humanoid robot to recover its actuators from unsafe thermal states is addressed. A first-order, data-driven, effort-based, thermal model of the robot's actuators is devised, which is used ... More
Monte Carlo Photoionization Simulations of Diffuse Ionized GasFeb 17 2004We demonstrate that the observed increase of some nebular line ratios with height above the midplane in the diffuse ionized gas (DIG) in the Milky Way and other galaxies is a natural consequence of the progressive hardening of the radiation field far ... More
Transport and mixing in the radiation zones of rotating stars II. Axisymmetric magnetic fieldJun 06 2005The purpose of this paper is to improve the modeling of the mixing of chemical elements that occurs in stellar radiation zones. In addition to the classical rotational mixing considered in our previous paper, which results of the combined action of the ... More
The Effects of Clumping on Derived Abundances in H II RegionsMar 26 2005We have compared Monte Carlo photoionization models of H II regions with a uniform density distribution with models with the same central stars and chemical compositions but with 3-D hierarchical clumps. We compare the abundances of He, N, O, Ne, and ... More
Tides and angular momentum redistribution inside low-mass stars hosting planets: a first dynamical modelJun 28 2016We introduce a general mathematical framework to model the internal transport of angular momentum in a star hosting a close-in planetary/stellar companion. By assuming that the tidal and rotational distortions are small and that the deposit/extraction ... More
Transport and mixing by internal waves in stellar interiors: effect of the Coriolis forceJun 16 2007We briefly recall the physical background of the transport of angular momentum and the mixing of chemicals inside stellar radiation zones and its importance for stellar evolution. Then, we describe its present modeling, its successes and its weaknesses. ... More
Transport and mixing in the radiation zones of rotating stars: I-Hydrodynamical processesJun 18 2004The purpose of this paper is to improve the modelization of the rotational mixing which occurs in stellar radiation zones, through the combined action of the thermally driven meridional circulation and of the turbulence generated by the shear of differential ... More
A model of rotating convection in stellar and planetary interiors: I - convective penetrationFeb 27 2019A monomodal model for stellar and planetary convection is derived for the magnitude of the rms velocity, degree of superadiabaticity, and characteristic length scale as a function of rotation rate as well as with thermal and viscous diffusivities. The ... More
A first family of stable configurations to model magnetic fields in stellar radiation zonesSep 28 2010We conduct 3D magneto-hydrodynamic (MHD) simulations in order to test the stability of the magnetic equilibrium configuration described by Duez & Mathis (2010). This analytically-derived configuration describes the lowest energy state for a given helicity ... More
On the Stability of Non Force-Free Magnetic Equilibria in StarsSep 27 2010The existence of stable magnetic configurations in white dwarfs, neutron stars and various non-convective stellar {regions} is now well recognized. It has recently been shown numerically that various families of equilibria, including axisymmetric mixed ... More
On shear-induced turbulence in rotating starsMar 24 2004We review various prescriptions which have been proposed for the turbulent transport of matter and angular momentum in differentially rotating stellar radiation zones. A new prescription is presented for the horizontal transport associated with the anisotropic ... More
The 2D dynamics of radiative zones of low-mass starsNov 23 2017In the context of secular evolution, we describe the dynamics of the radiative core of low-mass stars to understand the internal transport of angular momentum in such stars which results in a solid rotation in the Sun from 0.7R_sun to 0.2R_sun and a weak ... More
Understanding tidal dissipation in gaseous giant planets from their core to their surfaceNov 03 2014Tidal dissipation in planetary interiors is one of the key physical mechanisms that drive the evolution of star-planet and planet-moon systems. Tidal dissipation in planets is intrinsically related to their internal structure. In particular, fluid and ... More
Dependence of Gas Phase Abundances in the ISM on Column DensityOct 02 2000Sightlines through high- and intermediate-velocity clouds allow measurements of ionic gas phase abundances, A, at very low values of HI column density, N(HI). Present observations cover over 4 orders of magnitude in N(HI). Remarkably, for several ions ... More
Calculating Cross Sections of Composite Interstellar GrainsAug 21 1999Interstellar grains may be composite collections of particles of distinct materials, including voids, agglomerated together. We determine the various optical cross sections of such composite grains, given the optical properties of each constituent, using ... More
Understanding tidal dissipation in gaseous giant planets : the respective contributions of their core and envelopeOct 20 2014Tidal dissipation in planetary interiors is one of the key physical mechanisms that drive the evolution of star-planet and planet-moon systems. New constraints are now obtained both in the Solar and exoplanetary systems. Tidal dissipation in planets is ... More
The effects of rotation on wave-induced transport in stars: from weakly to strongly stratified radiative zonesNov 07 2018Internal waves propagating in stellar radiative zones can lead to efficient angular momentum transport, that should occur throughout the whole lifetime of stars. They thus play a key role in shaping the internal rotation profile of these regions, that ... More
Voids in the Simulated Local UniverseJan 12 2002We use simulations of the formation and evolution of the galaxy population in the Local Universe to address the issue of whether the standard theoretical model succeeds in producing empty regions as large and as dark as the observed nearby ones. We follow ... More
The equilibrium tide in stars and giant planets: I - the coplanar caseMay 16 2012Since 1995, more than 500 extrasolar planets have been discovered orbiting very close to their parent star, where they experience strong tidal interactions. Their orbital evolution depends on the physical mechanisms that cause tidal dissipation, and these ... More
Layered semi-convection and tides in giant planet interiorsOct 27 2017Layered semi-convection could operate in giant planets, potentially explaining the constraints on the heavy elements distribution in Jupiter deduced recently from Juno observations, and contributing to Saturn's luminosity excess or the abnormally large ... More
Generation of entangled states of two three-level atoms in cavity QEDMar 04 2003We present a scheme to generate maximally entangled states of two three-level atoms with a nonresonant cavity by cavity-assisted collisions. Since the cavity field is only virtually excited no quantum information will be transferred from the atoms to ... More
Scheme for the generation of an entangled four-photon W-stateFeb 16 2002Aug 29 2002We present a scheme to produce an entangled four-photon W-state by using linear optical elements. The symmetrical setup of linear optical elements consists of four beam splitters, four polarization beam splitters and four mirrors. A photon EPR-pair and ... More
Generation of any superposition of Dicke state of excitons in coupled quantum dotsJan 04 2002Jan 08 2002We present a scheme to generate arbitrary superposition of the Dicke states of excitons in optically driven quantum dots. This proposal is based on a sequence of laser pulses, which are tuned appropriately to control transitions on Dicke state. It is ... More
Quantum computation with trapped ions in strongly detuned optical cavityDec 10 2001We propose a scheme to implement quantum phase gate for two $\Lambda$ ions trapped in optical cavity. It is shown that quantum phase gate can be implemented by applying a laser addressing to a single ions in strongly detuned optical cavity. We further ... More
The entanglement concentration and purification for entangled polarization photon stateNov 08 2001We present a concentration and purification scheme for nonmaximally entangled pure and mixed porization entangled state. We firstly show that two distant parties Alice and Bob first start with two shared but less entangled photon pure states to produce ... More
The feasible generation of entangled photon states by using linear optical elementsOct 30 2001May 03 2002We present a feasible scheme to produce a polarization-entangled photon states $\frac{1}{\sqrt{2}}(|H>|V>+|V>|H>)$ in a controllable way. This scheme requires single-photon sources, linear optical elements and photon detectors. It generates the entanglement ... More
Generation of arbitrary two dimensional motional state of a trapped ionAug 27 2001Apr 13 2002We present a scheme to generate an arbitrary two-dimensional quantum state of motion of a trapped ion. This proposal is based on a sequence of laser pulses, which are tuned appropriately to control transitions on the sidebands of two modes of vibration. ... More
Layered semi-convection and tides in giant planet interiors - I. Propagation of internal wavesApr 28 2017Layered semi-convection is a possible candidate to explain Saturn's luminosity excess and the abnormally large radius of some hot Jupiters. In giant planet interiors, it could lead to the creation of density staircases, which are convective layers separated ... More
Secondary discharge studies in single and multi GEM structuresJan 17 2019Jan 21 2019Secondary discharges, which consist of the breakdown of a gap near a GEM foil upon a primary discharge across that GEM, are studied in this work. Their main characteristics are the occurrence a few $10\,\mu \textrm{s}$ after the primary, the relatively ... More
On magnetic instabilities and dynamo action in stellar radiation zonesJul 23 2007We examine the MHD instabilities arising in the radiation zone of a differentially rotating star, in which a poloidal field of fossil origin is sheared into a toroidal field. We focus on the non-axisymmetric instability that affects the toroidal magnetic ... More
Electronic structure of Li2Pd3B and Li2Pt3BFeb 22 2005Li2Pd3B is known to be superconducting, while the isotypical Li2Pt3B compound is not. Electronic structures of Li2Pd3B and Li2Pt3B have been calculated in order to obtain an insight into this surprising difference, through an analysis of the differences ... More
Scaling laws to understand tidal dissipation in fluid planetary regions and stars I - Rotation, stratification and thermal diffusivityJun 25 2015Tidal dissipation in planets and stars is one of the key physical mechanisms driving the evolution of star-planet and planet-moon systems. Several signatures of its action are observed in planetary systems thanks to their orbital architecture and the ... More
Be star outbursts: transport of angular momentum by wavesNov 11 2013The Be phenomenon, that is the ejection of matter from Be stars into a circumstellar disk, has been a long lasting mystery. In the last few years, the CoRoT (Convection, Rotation and planetary Transits) satellite brought clear evidence that Be outbursts ... More
Magnetic energy cascade in spherical geometry: I. The stellar convective dynamo caseJan 08 2013We present a method to characterize the spectral transfers of magnetic energy between scales in simulations of stellar convective dynamos. The full triadic transfer functions are computed thanks to analytical coupling relations of spherical harmonics ... More
Attempts to reproduce the rotation profile of the red giant KIC 7341231 observed by KeplerOct 22 2012Thanks to the asteroseimic study of the red giant star KIC 7341231 observed by Kepler, it has been possible to infer its radial differential rotation profile (Deheuvels et al. 2012). This opens new ways to constrain the physical mechanisms responsible ... More
Tidal interactions in rotating multiple stars and their impact on their evolutionOct 12 2014Tidal dissipation in stars is one of the key physical mechanisms that drive the evolution of binary and multiple stars. As in the Earth oceans, it corresponds to the resonant excitation of their eigenmodes of oscillation and their damping. Therefore, ... More
The anelastic equilibrium tide in exoplanetary systemsAug 01 2012Earth-like planets have anelastic mantles, whereas giant planets may have anelastic cores. As for the fluid parts of a body, the tidal dissipation of such solid regions, gravitationally perturbed by a companion body, highly depends on its internal friction, ... More
Free inertial modes in differentially rotating convective envelopes of low-mass stars : numerical explorationOct 20 2015Tidally-excited inertial waves in stellar convective regions are a key mechanism for tidal dissipation in stars and therefore the evolution of close-in binary or planetary systems. As a first step, we explore here the impact of latitudinal differential ... More
Impact of the frequency dependence of tidal Q on the evolution of planetary systemsNov 19 2013Context. Tidal dissipation in planets and in stars is one of the key physical mechanisms that drive the evolution of planetary systems. Aims. Tidal dissipation properties are intrisically linked to the internal structure and the rheology of studied celestial ... More
Can Reflection from Grains Diagnose the Albedo?Apr 02 2002By radiation transfer models with a realistic power spectra of the projected density distributions, we show that the optical properties of grains are poorly constrained by observations of reflection nebulae. The ISM is known to be hierarchically clumped ... More
Scaling laws to understand tidal dissipation in fluid planetary layers and starsOct 12 2014Tidal dissipation is known as one of the main drivers of the secular evolution of planetary systems. It directly results from dissipative mechanisms that occur in planets and stars' interiors and strongly depends on the structure and dynamics of the bodies. ... More
Interlayer Exchange Coupling in M/N/M MultilayerNov 08 2001The interlayer exchange coupling (IEC) of two local moment ferromagnetic layers separated by a non-magnetic spacer layer (M/N/M multilayer) is studied using the modified RKKY method along with the s-f model. The IEC exhibits oscillatory behaviour with ... More
Dust heating by the interstellar radiation field in models of turbulent molecular cloudsApr 02 2004We have calculated the radiation field, dust grain temperatures, and far infrared emissivity of numerical models of turbulent molecular clouds. When compared to a uniform cloud of the same mean optical depth, most of the volume inside the turbulent cloud ... More
Understanding angular momentum transport in red giants: the case of KIC 7341231May 24 2013Context. Thanks to recent asteroseismic observations, it has been possible to infer the radial differential rotation profile of subgiants and red giants. Aims. We want to reproduce through modeling the observed rotation profile of the early red giant ... More
Inertial waves in differentially rotating low-mass stars and tidesOct 13 2014Star-planet tidal interactions may result in the excitation of inertial waves in the convective region of stars. Their dissipation plays a prominent role in the long-term orbital evolution of short-period planets. If the star is assumed to be rotating ... More
Combining magnetic and seismic studies to constrain processes in massive starsNov 10 2013The presence of pulsations influences the local parameters at the surface of massive stars and thus it modifies the Zeeman magnetic signatures. Therefore it makes the characterisation of a magnetic field in pulsating stars more difficult and the characterisation ... More
Anelastic tidal dissipation in multi-layer planetsApr 06 2012Earth-like planets have viscoelastic mantles, whereas giant planets may have viscoelastic cores. The tidal dissipation of such solid regions, gravitationally perturbed by a companion body, highly depends on their rheology and on the tidal frequency. Therefore, ... More
Mode excitation by turbulent convection in rotating stars. I. Effect of uniform rotationSep 08 2009Oct 08 2009We focus on the influence of the Coriolis acceleration on the stochastic excitation of oscillation modes in convective regions of rotating stars. Our aim is to estimate the asymmetry between excitation rates of prograde and retrograde modes. We extend ... More
Tidal inertial waves in the differentially rotating convective envelopes of low-mass stars - I. Free oscillation modesJan 18 2016Star-planet tidal interactions may result in the excitation of inertial waves in the convective region of stars. In low-mass stars, their dissipation plays a prominent role in the long-term orbital evolution of short-period planets. Turbulent convection ... More
The surface signature of the tidal dissipation of the core in a two-layer planetSep 29 2014Tidal dissipation, which is directly linked to internal structure, is one of the key physical mechanisms that drive systems evolution and govern their architecture. A robust evaluation of its amplitude is thus needed to predict evolution time for spins ... More
gamma Peg: testing Vega-like magnetic fields in B starsDec 12 2013gam Peg is a bright B pulsator showing both p and g modes of beta Cep and SPB types. It has also been claimed to be a magnetic star by some authors while others do not detect a magnetic field. We aimed at checking for the presence of a field, characterise ... More
Remarks on some open problems in phase-field modelling of solidificationApr 26 2010Three different topics in phase-field modelling of solidification are discussed, with particular emphasis on the limitations of the currently available modelling approaches. First, thin-interface limits of two-sided phase-field models are examined, and ... More
The rotation of planets hosting atmospheric tides: from Venus to habitable super-earthsNov 17 2016The competition between the torques induced by solid and thermal tides drives the rotational dynamics of Venus-like planets and super-Earths orbiting in the habitable zone of low-mass stars. The tidal responses of the atmosphere and telluric core are ... More
Automatic Electrodes Detection during simultaneous EEG/fMRI acquisitionSep 17 2018Simultaneous EEG/fMRI acquisition allows to measure brain activity at high spatial-temporal resolution. The localisation of EEG sources depends on several parameters including the position of the electrodes on the scalp. The position of the MR electrodes ... More
The dynamics of the radiative zone of the SunJan 06 2011Helioseismology puts strong constraints on the internal sound speed and on the rotation profile in the radiative zone. Young stars of solar type are more active and faster rotators than the Sun. So we begin to build models which include different rotation ... More
Unified derivation of phase-field models for alloy solidification from a grand-potential functionalMay 09 2011In the literature, two quite different phase-field formulations for the problem of alloy solidification can be found. In the first, the material in the diffuse interfaces is assumed to be in an intermediate state between solid and liquid, with a unique ... More
From gated to continuous readout - the GEM upgrade of the ALICE TPCMar 12 2018The ALICE Collaboration is planning a major upgrade of its central barrel detectors to be able to cope with the increased LHC luminosity beyond 2020. In order to record at an increased interaction rate of up to 50$\,$kHz in Pb$-$Pb collisions, the TPC ... More
The fate of close-in planets: tidal or magnetic migration?Sep 18 2017Planets in close-in orbits interact magnetically and tidally with their host stars. These interactions lead to a net torque that makes close-in planets migrate inward or outward depending on their orbital distance. We compare systematically the strength ... More
Characterizing the propagation of gravity waves in 3D nonlinear simulations of solar-like starsAug 13 2015The revolution of helio- and asteroseismology provides access to the detailed properties of stellar interiors by studying the star's oscillation modes. Among them, gravity (g) modes are formed by constructive interferences between progressive internal ... More
Modelling turbulent stellar convection zones: sub-grid scales effectsMay 27 2016The impressive development of global numerical simulations of turbulent stellar interiors unveiled a variety of possible differential rotation (solar or anti-solar), meridional circulation (single or multi-cellular), and dynamo states (stable large scale ... More
Diagnoses to unravel secular hydrodynamical processes in rotating main sequence starsDec 01 2008(Abridged) We present a detailed analysis of the main physical processes responsible for the transport of angular momentum and chemical species in the radiative regions of rotating stars. We focus on cases where meridional circulation and shear-induced ... More
Simulating the Formation of the Local Galaxy PopulationNov 05 2001We simulate the formation and evolution of the local galaxy population starting from initial conditions with a smoothed linear density field which matches that derived from the IRAS 1.2 Jy galaxy survey. Our simulations track the formation and evolution ... More
Evolution of star-planet systems under magnetic braking and tidal interactionNov 15 2018With the discovery over the last two decades of a large diversity of exoplanetary systems, it is now of prime importance to characterize star-planet interactions and how such systems evolve. We address this question by studying systems formed by a solar-like ... More
Roadmap on the theoretical work of BinaMIcSNov 11 2013Nov 12 2013We review the different theoretical challenges concerning magnetism in interacting binary or multiple stars that will be studied in the BinaMIcS (Binarity and Magnetic Interactions in various classes of Stars) project during the corresponding spectropolarimetric ... More
The origin of magnetic fields in hot starsFeb 01 2015Observations of stable mainly dipolar magnetic fields at the surface of ~7% of single hot stars indicate that these fields are of fossil origin, i.e. they descend from the seed field in the molecular clouds from which the stars were formed. Recent results ... More
High-frequency gate manipulation of a bilayer graphene quantum dotJun 19 2012We report transport data obtained for a double-gated bilayer graphene quantum dot. In Coulomb blockade measurements, the gate dielectric Cytop(TM) is found to provide remarkable electronic stability even at cryogenic temperatures. Moreover, we demonstrate ... More
The dramatic change of the fossil magnetic field of HD 190073: evidence of the birth of the convective core in a Herbig star ?Jan 09 2013In the context of the ESPaDOnS and Narval spectropolarimetric surveys of Herbig Ae/Be stars, we discovered and then monitored the magnetic field of HD 190073 over more than four years, from 2004 to 2009. Our observations all displayed similar Zeeman signatures ... More
Multisite spectroscopic seismic study of the beta Cep star V2052 Oph: inhibition of mixing by its magnetic fieldAug 21 2012We used extensive ground-based multisite and archival spectroscopy to derive observational constraints for a seismic modelling of the magnetic beta Cep star V2052 Ophiuchi. The line-profile variability is dominated by a radial mode (f_1=7.14846 d^{-1}) ... More
Effects of rotational mixing on the asteroseismic properties of solar-type starsSep 23 2010The influence of rotational mixing on the evolution and asteroseismic properties of solar-type stars is studied. Rotational mixing changes the global properties of a solar-type star with a significant increase of the effective temperature resulting in ... More
Advances in secular magnetohydrodynamics of stellar interiors dedicated to asteroseismic spatial missionsMar 06 2007With the first light of COROT, the preparation of KEPLER and the future helioseismology spatial projects such as GOLF-NG, a coherent picture of the evolution of rotating stars from their birth to their death is needed. We describe here the modelling of ... More
Onset of cavitation in the quark-gluon plasmaMay 08 2014Jul 11 2014We study the onset of bubble formation (cavitation) in the quark-gluon plasma as a result of the reduction of the effective pressure from bulk-viscous corrections. By calculating velocity gradients in typical models for quark-gluon plasma evolution in ... More
Spiral surface growth without desorptionSep 25 1998Nov 18 1998Spiral surface growth is well understood in the limit where the step motion is controlled by the local supersaturation of adatoms near the spiral ridge. In epitaxial thin-film growth, however, spirals can form in a step-flow regime where desorption of ... More
Defects and multistability in eutectic solidification patternsMay 30 2010We use three-dimensional phase-field simulations to investigate the dynamics of the two-phase composite patterns formed upon during solidification of eutectic alloys. Besides the spatially periodic lamellar and rod patterns that have been widely studied, ... More
Stability of hexagonal solidification patternsJul 12 2002Jan 21 2004We investigate the dynamics of cellular solidification patterns using three-dimensional phase-field simulations. The cells can organize into stable hexagonal patterns or exhibit unsteady evolutions. We identify the relevant secondary instabilities of ... More
Penetration of Rotating ConvectionNov 11 2018A simplified model for stellar and planetary convection is derived for the magnitude of the rms velocity, degree of superadiabaticity, and characteristic length scale with Rossby number as well as with thermal and viscous diffusivities. Integrating the ... More
Influence of stellar structure, evolution and rotation on the tidal damping of exoplanetary spin-orbit anglesMar 26 2018It is debated whether close-in giant planets can form in-situ and if not, which mechanisms are responsible for their migration. One of the observable tests for migration theories is the current value of the angle between the stellar equatorial plane and ... More
Stochastic excitation of gravity waves in rapidly rotating massive starsAug 18 2014Stochastic gravity waves have been recently detected and characterised in stars thanks to space asteroseismology and they may play an important role in the evolution of stellar angular momentum. In this context, the observational study of the CoRoT hot ... More
Does magnetic field modify tidal dynamics in the convective envelope of Solar mass stars?Nov 21 2018The energy dissipation of wave-like tidal flows in the convective envelope of low-mass stars is one of the key physical mechanisms that shape the orbital and rotational dynamics of short-period planetary systems. Tidal flows, and the excitation, propagation, ... More
Testing tidal theory for evolved stars by using red-giant binaries observed by KeplerJun 19 2018Tidal interaction governs the redistribution of angular momentum in close binary stars and planetary systems and determines the systems evolution towards the possible equilibrium state. Turbulent friction acting on the equilibrium tide in the convective ... More
Modeling phase transition and metastable phasesFeb 06 2014We propose a model that describes phase transition including metastable phases present in the van der Waals Equation of State (EoS). We introduce a dynamical system that is able to depict the mass transfer between two phases, for which equilibrium states ... More
Eutectic Colony Formation: A Stability AnalysisDec 23 1998Feb 20 2000Experiments have widely shown that a steady-state lamellar eutectic solidification front is destabilized on a scale much larger than the lamellar spacing by the rejection of a dilute ternary impurity and forms two-phase cells commonly referred to as `eutectic ... More
Eutectic colony formation: A phase field studyDec 11 2001Eutectic two-phase cells, also known as eutectic colonies, are commonly observed during the solidification of ternary alloys when the composition is close to a binary eutectic valley. In analogy with the solidification cells formed in dilute binary alloys, ... More
Asteroseismology and spectropolarimetry: opening new windows on the internal dynamics of massive starsAug 19 2014In this article, we show how asteroseismology and spectropolarimetry allow to probe dynamical processes in massive star interiors. First, we give a summary of the state-of-the-art. Second, we recall the MHD mechanisms that take place in massive stars. ... More
The emission nebula associated with V1974 Cyg: a unique object?Jul 25 2000Jul 26 2000Through a program of narrow band imaging, we have observed the changing structure of the H alpha emission line around Nova Cyg 1992 (V1974 Cyg) at regular intervals from 1996 to 1999. Between 1994 and 1996, the nebular boundary advanced to the southwest ... More
Forward seismic modelling of the pulsating magnetic B-type star HD 43317May 02 2018May 31 2018The large-scale magnetic fields detected at the surface of about 10% of hot stars extend into the stellar interior, where they may alter the structure. Deep inner regions of stars are only observable using asteroseismology. Here, we investigated the pulsating ... More
BD-19 5044L: discovery of a short-period SB2 system with a magnetic Bp primary in the open cluster IC 4725Jan 24 2017Until recently almost nothing was known about the evolution of magnetic fields found in upper main sequence Ap/Bp stars during their long main sequence lifetime. We are thus studying magnetic Ap/Bp stars in open clusters in order to obtain observational ... More
Multiscale Finite-Difference-Diffusion-Monte-Carlo Method for Simulating Dendritic SolidificationFeb 01 2000We present a novel hybrid computational method to simulate accurately dendritic solidification in the low undercooling limit where the dendrite tip radius is one or more orders of magnitude smaller than the characteristic spatial scale of variation of ... More
Multiscale Random-Walk Algorithm for Simulating Interfacial Pattern FormationJun 24 1999Feb 01 2000We present a novel computational method to simulate accurately a wide range of interfacial patterns whose growth is limited by a large scale diffusion field. To illustrate the computational power of this method, we demonstrate that it can be used to simulate ... More
Influence of interphase anisotropy on lamellar eutectic growth patternsJun 29 2015It is well documented in many experiments that crystallographic effects play an important role in the generation of two-phase patterns during the solidification of eutectic alloys. In particular, in lamellar composites, large patches of perfectly aligned ... More
Phase-field modeling of the discontinuous precipitation reactionSep 03 2008A multi-phase-field model for the description of the discontinuous precipitation reaction is formulated which takes into account surface diffusion along grain boundaries and interfaces as well as volume diffusion. Simulations reveal that the structure ... More