Références de "Salmon, Sébastien"
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Voir détailDetermining the metallicity of the solar envelope using seismic inversion techniques
Buldgen, Gaël ULiege; Salmon, Sébastien ULiege; Noels-Grötsch, Arlette ULiege et al

in Monthly Notices of the Royal Astronomical Society (2017), 472(1), 751-764

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 ... [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: 23 (3 ULiège)
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Voir détailInversions of the Ledoux discriminant: a closer look at the tachocline
Buldgen, Gaël ULiege; Salmon, Sébastien ULiege; Godart, Mélanie ULiege et al

in Monthly Notices of the Royal Astronomical Society : Letters (2017), 472(1), 70-74

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 ... [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 (7 ULiège)
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Voir détailNANESSE: a Nanosatellite for Asteroseismology of the Nearest Stellar System with Exoplanets
Salmon, Sébastien ULiege; Van Grootel, Valérie ULiege

Conférence scientifique (2017, September 15)

Visualisation de la référence détaillée: 33 (9 ULiège)
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Voir détailThe γ Dor stars as revealed by Kepler: A key to reveal deep-layer rotation in A and F stars
Salmon, Sébastien ULiege; Ouazzani, R.-M.; Antoci, V. et al

in EPJ Web of Conferences (2017, September 08), 152

Visualisation de la référence détaillée: 28 (3 ULiège)
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Voir détailPeriod–luminosity relations of fast-rotating B-type stars in the young open cluster NGC 3766
Saio, H.; Ekström, S.; Mowlavi, N. et al

in Monthly Notices of the Royal Astronomical Society (2017), 467(4), 3864-3873

We study the pulsational properties of rapidly rotating main-sequence B-type stars using linear non-adiabatic analysis of non-radial low-frequency modes taking into account the effect of rotation. We ... [plus ▼]

We study the pulsational properties of rapidly rotating main-sequence B-type stars using linear non-adiabatic analysis of non-radial low-frequency modes taking into account the effect of rotation. We compare the properties of prograde sectoral g and retrograde r modes excited by the κ mechanism at the Fe opacity peak with the newly discovered period–luminosity relation that is obeyed by a group of fast-rotating B-type stars in the young open cluster NGC 3766. The observed relation consists of two sequences in the period versus magnitude diagram, at periods shorter than 0.5 d. We find that this property is consistent with similar period–luminosity relations predicted for excited sectoral prograde g modes of azimuthal orders m = −1 and −2 in fast-rotating stars along an isochrone. We further show that some of the rapidly rotating stars that have photometric variability with periods longer than a day may be caused by r-mode pulsation predicted to be excited in these stars. One fast-rotating star, in particular, shows both short and long periods that can be explained by the simultaneous excitation of g- and r-mode pulsations in models of fast-rotating stars. [moins ▲]

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Voir détailConstraining the efficiency of angular momentum transport with asteroseismology of red giants: the effect of stellar mass
Eggenberger, P.; Lagarde, N.; Miglio, A. et al

in Astronomy and Astrophysics (2017), 599

Context: Constraints on the internal rotation of red giants are now available thanks to asteroseismic observations. Preliminary comparisons with rotating stellar models indicate that an undetermined ... [plus ▼]

Context: Constraints on the internal rotation of red giants are now available thanks to asteroseismic observations. Preliminary comparisons with rotating stellar models indicate that an undetermined additional process for the internal transport of angular momentum is required in addition to purely hydrodynamic processes. Aims: We investigate how asteroseismic measurements of red giants can help us characterize the additional transport mechanism. Methods: We first determine the efficiency of the missing transport mechanism for the low-mass red giant KIC 7341231 by computing rotating models that include an additional viscosity corresponding to this process. We then discuss the change in the efficiency of this transport of angular momentum with the mass, metallicity and evolutionary stage. Results: In the case of the low-mass red giant KIC 7341231, we find that the viscosity corresponding to the additional mechanism is constrained to the range 1 x 10^3 - 1.3 x 10^4 cm^2/s. This constraint on the efficiency of the unknown additional transport mechanism during the post-main sequence is obtained independently of any specific assumption about the modelling of rotational effects during the pre-main sequence and the main sequence (in particular, the braking of the surface by magnetized winds and the efficiency of the internal transport of angular momentum before the post-main-sequence phase). When we assume that the additional transport mechanism is at work during the whole evolution of the star together with a solar-calibrated braking of the surface by magnetized winds, the range of nu_add is reduced to 1 - 4 x 10^3 cm^2/s. In addition to being sensitive to the evolutionary stage of the star, we show that the efficiency of the unknown process for internal transport of angular momentum increases with the stellar mass. [moins ▲]

Visualisation de la référence détaillée: 40 (3 ULiège)
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Voir détailA new asteroseismic diagnostic for internal rotation in γ Doradus stars
Ouazzani, Rhita-Maria; Salmon, Sébastien ULiege; Antoci, V. et al

in Monthly Notices of the Royal Astronomical Society (2017), 465

With four years of nearly-continuous photometry from Kepler, we are finally in a good position to apply asteroseismology to $\gamma$ Doradus stars. In particular several analyses have demonstrated the ... [plus ▼]

With four years of nearly-continuous photometry from Kepler, we are finally in a good position to apply asteroseismology to $\gamma$ Doradus stars. In particular several analyses have demonstrated the possibility to detect non-uniform period spacings, which have been predicted to be directly related to rotation. In the present work, we define a new seismic diagnostic for rotation in $\gamma$ Doradus stars that are too rapidly rotating to present rotational splittings. Based on the non uniformity of their period spacings, we define the observable $\Sigma$ as the slope of the period spacing when plotted as a function of period. We provide a one-to-one relation between this observable $\Sigma$ and the internal rotation, which applies widely in the instability strip of $\gamma$ Doradus stars. We apply the diagnostic to a handful of stars observed by Kepler. Thanks to g-modes in $\gamma$ Doradus stars, we are now able to determine the internal rotation of stars on the lower main sequence, which is still not possible for Sun-like stars. [moins ▲]

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Voir détailThe IACOB project. IV. New predictions for high-degree non-radial mode instability domains in massive stars and their connection with macroturbulent broadening
Godart, Mélanie ULiege; Simón-Díaz, S.; Herrero, A. et al

in Astronomy and Astrophysics (2016), 597

Context. Asteroseismology is a powerful tool to access the internal structure of stars. Apart from the important impact of theoretical developments, progress in this field has been commonly associated ... [plus ▼]

Context. Asteroseismology is a powerful tool to access the internal structure of stars. Apart from the important impact of theoretical developments, progress in this field has been commonly associated with the analysis of time-resolved observations. Recently, the so-called macroturbulent broadening has been proposed as a complementary and less expensive way - in terms of observational time - to investigate pulsations in massive stars. <BR /> Aims: We assess to what extent this ubiquitous non-rotational broadening component which shapes the line profiles of O stars and B supergiants is a spectroscopic signature of pulsation modes driven by a heat mechanism. <BR /> Methods: We compute stellar main-sequence and post-main-sequence models from 3 to 70 M[SUB]⊙[/SUB] with the ATON stellar evolution code, and determine the instability domains for heat-driven modes for degrees ℓ = 1-20 using the adiabatic and non-adiabatic codes LOSC and MAD. We use the observational material compiled in the framework of the IACOB project to investigate possible correlations between the single snapshot line-broadening properties of a sample of ≈260 O and B-type stars and their location inside or outside the various predicted instability domains. <BR /> Results: We present an homogeneous prediction for the non-radial instability domains of massive stars for degree ℓ up to 20. We provide a global picture of what to expect from an observational point of view in terms of the frequency range of excited modes, and we investigate the behavior of the instabilities with respect to stellar evolution and the degree of the mode. Furthermore, our pulsational stability analysis, once compared to the empirical results, indicates that stellar oscillations originated by a heat mechanism cannot explain alone the occurrence of the large non-rotational line-broadening component commonly detected in the O star and B supergiant domain. Based on observations made with the Nordic Optical Telescope, operated by NOTSA, and the Mercator Telescope, operated by the Flemish Community, both at the Observatorio del Roque de los Muchachos (La Palma, Spain) of the Instituto de Astrofísica de Canarias. [moins ▲]

Visualisation de la référence détaillée: 15 (2 ULiège)
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Voir détailIn-depth study of 16CygB using inversion techniques
Buldgen, Gaël ULiege; Salmon, Sébastien ULiege; Reese, D. R. et al

in Astronomy and Astrophysics (2016), 596

Context. The 16Cyg binary system hosts the solar-like Kepler targets with the most stringent observational constraints. Indeed, we benefit from very high quality oscillation spectra, as well as ... [plus ▼]

Context. The 16Cyg binary system hosts the solar-like Kepler targets with the most stringent observational constraints. Indeed, we benefit from very high quality oscillation spectra, as well as spectroscopic and interferometric observations. Moreover, this system is particularly interesting since both stars are very similar in mass but the A component is orbited by a red dwarf, whereas the B component is orbited by a Jovian planet and thus could have formed a more complex planetary system. In our previous study, we showed that seismic inversions of integrated quantities could be used to constrain microscopic diffusion in the A component. In this study, we analyse the B component in the light of a more regularised inversion. <BR /> Aims: We wish to analyse independently the B component of the 16Cyg binary system using the inversion of an indicator dedicated to analyse core conditions, denoted t[SUB]u[/SUB]. Using this independent determination, we wish to analyse any differences between both stars due to the potential influence of planetary formation on stellar structure and/or their respective evolution. <BR /> Methods: First, we recall the observational constraints for 16CygB and the method we used to generate reference stellar models of this star. We then describe how we improved the inversion and how this approach could be used for future targets with a sufficient number of observed frequencies. The inversion results were then used to analyse the differences between the A and B components. <BR /> Results: The inversion of the t[SUB]u[/SUB] indicator for 16CygB shows a disagreement with models including microscopic diffusion and sharing the chemical composition previously derived for 16CygA. We show that small changes in chemical composition are insufficient to solve the problem but that extra mixing can account for the differences seen between both stars. We use a parametric approach to analyse the impact of extra mixing in the form of turbulent diffusion on the behaviour of the t[SUB]u[/SUB] values. We conclude on the necessity of further investigations using models with a physically motivated implementation of extra mixing processes including additional constraints to further improve the accuracy with which the fundamental parameters of this system are determined. [moins ▲]

Visualisation de la référence détaillée: 29 (2 ULiège)
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Voir détailModels of rotating stars constrained by asteroseismic measurements of red giants
Eggenberger, P.; Lagarde, N.; Miglio, A. et al

in Astronomische Nachrichten (2016, September 01), 337(8-9), 832-836

Solar-like oscillations have now been characterized for a large number of stars, thanks to asteroseismic data obtained recently by space missions. This has led to the determination of the global and ... [plus ▼]

Solar-like oscillations have now been characterized for a large number of stars, thanks to asteroseismic data obtained recently by space missions. This has led to the determination of the global and internal properties of these stars. In particular, core rotation rates have been obtained for red-giant stars, which is of prime importance to progress in the modelling of the dynamical processes at work in stellar interiors. In this presentation, we discuss which constraints can be brought by these asteroseismic measurements on stellar models that include rotational effects. Similarly to the solar case, we show that an efficient mechanism is required for the transport of angular momentum in the radiative zones of red giants. The efficiency of this transport process can be determined by asteroseismic observations of red-giant stars. [moins ▲]

Visualisation de la référence détaillée: 31 (7 ULiège)
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Voir détailAsteroseismic hare & hound exercises: the case of β Cephei stars
Salmon, Sébastien ULiege; Montalbán, J.; Miglio, A. et al

in Martins, F.; Boissier, S.; Buat, V. (Eds.) et al SF2A-2015: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics. Eds.: F. Martins, S. Boissier, V. Buat, L. Cambrésy, P. Petit, pp.423-428 (2015, December 01)

The β Cephei pulsating stars present a unique opportunity to test and probe our knowledge of the interior of massive stars. The information that we can get depends on the quality and number of ... [plus ▼]

The β Cephei pulsating stars present a unique opportunity to test and probe our knowledge of the interior of massive stars. The information that we can get depends on the quality and number of observational constraints, both seismic and classical ones. The asteroseismology of β Cephei stars proceeds by a forward approach, which can result in multiple solutions, without clear indication on the level of confidence. We seek a method to derive confidence intervals on stellar parameters and investigate how these latter behave depending on the seismic data accessible to the observer. We realise forward modelling with the help of a grid of pre-computed models. We also use Monte-Carlo simulations to build confidence intervals on the inferred stellar parameters. We apply and test this method in a series of hare and hound exercises on a subset of theoretical models simulating observed stars. Results show that a set of 5 frequencies (with knowledge of their associated angular degree) yields precise seismic constraints. Significant errors on the determination of the extent of the central mixed region may result when the theoretical models do not present the same chemical mixture as the observed star. [moins ▲]

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Voir détailFirst New Solar Models With Opas Opacity Tables
Le Pennec, Maëlle; Turck-Chièze, Sylvaine; Salmon, Sébastien ULiege et al

in Astrophysical Journal Letters (2015), 813(2), 42

Stellar seismology appears more and more as a powerful tool for a better determination of the fundamental properties of solar-type stars. However, the particular case of the Sun is still challenging. For ... [plus ▼]

Stellar seismology appears more and more as a powerful tool for a better determination of the fundamental properties of solar-type stars. However, the particular case of the Sun is still challenging. For about a decade now, the helioseismic sound-speed determination has continued to disagree with the standard solar model (SSM) prediction, questioning the reliability of this model. One of the sources of uncertainty could be in the treatment of the transport of radiation from the solar core to the surface. In this Letter, we use the new OPAS opacity tables, recently available for solar modeling, to address this issue. We discuss first the peculiarities of these tables, then we quantify their impact on the solar sound-speed and density profiles using the reduced OPAS tables taken on the grids of the OPAL ones. We use the two evolution codes, Modules for Experiments in Stellar Astrophysics and Code Liégeois d'Evolution Stellaire, that led to similar conclusions in the solar radiative zone. In comparison to commonly used OPAL opacity tables, the new solar models are computed for the most recent photospheric composition with OPAS tables and present improvements to the location of the base of the convective zone and to the description of the solar radiative zone in comparison to the helioseismic observations, even if the differences in the Rosseland mean opacity do not exceed 6%. We finally carry out a comparison to a solar model computed with the OP opacity tables. [moins ▲]

Visualisation de la référence détaillée: 32 (9 ULiège)
Voir détailOpacities in the massive stellar envelopes
Le Pennec, Maëlle; TURCK-CHIEZE, Sylvaine; Salmon, Sébastien ULiege et al

Communication orale (2015, August 01)

Helio and asteroseismology (SoHo, CoRoT, KEPLER...) have produced observed acoustic oscillations of thousands of stars. The characteristics of these oscillations are deeply linked to the transport of ... [plus ▼]

Helio and asteroseismology (SoHo, CoRoT, KEPLER...) have produced observed acoustic oscillations of thousands of stars. The characteristics of these oscillations are deeply linked to the transport of radiation inside the stars. However, the comparisons of seismic data of Sun and stars with model predictions have led to significant discrepancies, which could be due to a bad knowledge of production and transport of energy.We will focus here on the case of β-Cephei.β-Cephei are pulsating stars, progenitor of supernovae and thus deeply linked to our understanding of stellar medium enrichment. Their study has shown some difficulty to predict the observed oscillation modes, which are directly linked to a bump of the opacity of the elements of the iron group (Cr, Fe, Ni) at log T=5.25 through their pulsating mechanism called the κ-mechanism. We will show that the different parameters of the stars (mass, age, metallicity) have a great influence on the amplitude of the bump, and then on the structure of the considered star.The mastery of the κ-mechanism that produces the pulsation of these stars supposes a fine determination of the peak opacity of the iron group in their envelope. We will present the final results of an experiment conducted at LULI 2000 in 2011 on Cr, Fe and Ni and compare them to OP and ATOMIC, SCO-RCG codes. We will show how to improve the opacity in the range of temperature around log T= 5.3. [moins ▲]

Visualisation de la référence détaillée: 42 (0 ULiège)
Voir détailTesting stellar opacities with laser facilities
Le Pennec, Maëlle; TURCK-CHIEZE, Sylvaine; RIBEYRE, Xavier et al

Communication orale (2015, August 01)

Helio and asteroseismology (SoHo, KEPLER...) have produced observed acoustic oscillations of thousands of stars which characteristics are deeply linked to the transport of radiation inside the stars ... [plus ▼]

Helio and asteroseismology (SoHo, KEPLER...) have produced observed acoustic oscillations of thousands of stars which characteristics are deeply linked to the transport of radiation inside the stars. However, the comparisons of seismic data with model predictions have led to significant discrepancies, which could be due to a bad knowledge of production and transport of energy.β-Cephei are pulsating stars, progenitor of supernovae and thus deeply linked to our understanding of stellar medium enrichment. Their study has shown some difficulty to predict the observed oscillation modes, which are directly linked to an opacity bump of the elements of the iron group (Cr, Fe, Ni) at log T=5.25 (κ-mechanism). We will show that several parameters of the stars (mass, age, metallicity) have a great influence on the amplitude of the bump, which impact their structure. We will then present the final results of an experiment conducted at LULI 2000 in 2011 on Cr, Fe and Ni compared to several opacity codes. We will show how to improve the opacity in the range of temperature around log T= 5.3.The Sun is a privilege place to test and validate physics. Since the recent update of the solar composition, there is a well established large discrepancy (Turck-Chièze et al. 2001) between solar models and seismic data, visible on the solar sound speed profile comparison.An explanation could be that the calculations of energy transport are not correctly taken into account.Unfortunately, there are very few experiments to validate these calculations (Bailey et al. 2014). That's why we are proposing an opacity experiment on a high-energy laser like LMJ, in the conditions of the radiative zone. We are exploiting in that purpose an approach called the Double Ablation Front to reach these high temperatures and densities at LTE and validate or not plasma effects and line widths. We will show the principle of this technique and the results of our simulations on several elements.In the mean time, we are also exploiting new opacity calculations thanks to the OPAS code (Blancard et al. 2012) at the conditions of the solar radiative zone. We will show the impact of these calculations on the solar model. [moins ▲]

Visualisation de la référence détaillée: 46 (1 ULiège)
Voir détailWhat can we learn from asteroseismology of beta Cephei stars?
Salmon, Sébastien ULiege; Montalban, J.; Miglio, A. et al

Poster (2015, June 01)

Visualisation de la référence détaillée: 15 (0 ULiège)
Voir détailEx Parrot: The Aarhus-Sydney gamma Dor experiment on pulsations and rotation
Antoci, V.; Ouazzani, R.; Murphy, S. et al

Poster (2015, June 01)

γ Doradus stars, exhibiting pure gravity modes pulsations, occupy the region between the solar-like oscillators and the delta Sct stars in the HRD. The Kepler mission delivered data of unprecedented ... [plus ▼]

γ Doradus stars, exhibiting pure gravity modes pulsations, occupy the region between the solar-like oscillators and the delta Sct stars in the HRD. The Kepler mission delivered data of unprecedented quality spanning up to 4 years, allowing to resolve closely spaced modes to measure, e.g., period spacings and to infer internal rotation profiles. Here we present an ensemble study of all γ Doradus stars observed with the Kepler mission. We investigate among others the range of excited modes, their amplitudes and the impact of rotation on these quantities. Our aim is to better understand the pulsation excitation as well as the mode selection mechanism in these stars. Our results may help to also explain the lack of solar-like oscillators exhibiting g-modes pulsations on the main sequence, although the instability domains of γ Doradus and solar-like stars overlap. [moins ▲]

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Voir détailPLATO Simulator: Realistic simulations of expected observations
Marcos-Arenal, P.; Zima, W.; De Ridder, J. et al

Logiciel (2015)

PLATO Simulator is an end-to-end simulation software tool designed for the performance of realistic simulations of the expected observations of the PLATO mission but easily adaptable to similar types of ... [plus ▼]

PLATO Simulator is an end-to-end simulation software tool designed for the performance of realistic simulations of the expected observations of the PLATO mission but easily adaptable to similar types of missions. It models and simulates photometric time-series of CCD images by including models of the CCD and its electronics, the telescope optics, the stellar field, the jitter movements of the spacecraft, and all important natural noise sources. [moins ▲]

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Voir détailAnalyser et contraindre les opacités stellaires via les pulsations des étoiles B de séquence
Salmon, Sébastien ULiege; Truck-Chièze, S.; Le Pennec, M.

Communication orale (2015, June)

Les étoiles B de séquence principale, bien que peu nombreuses, présentent un intérêt particulier puisque les plus massives d'entre elles termineront leur évolution par un évènement de type effondrement du ... [plus ▼]

Les étoiles B de séquence principale, bien que peu nombreuses, présentent un intérêt particulier puisque les plus massives d'entre elles termineront leur évolution par un évènement de type effondrement du coeur. Parmis les diverses étoiles pulsantes du diagramme d'Hertzsprung-Russell, nous avons la chance de trouver deux types de pulsation au sein des étoiles B de séquence : d'une part celles de type beta Cephei, correspondant à des modes de gravité et acoustiques d'ordres faibles, et d'autre part celles de type SPB (Slowly Pulsating B stars), correspondant à des modes de gravité d'ordres élevés. En étudiant ces pulsations, nous pouvons ainsi améliorer notre connaissance des processus physiques internes des étoiles B de séquence. Nous nous intéressons au cas récent de la détection d'étoiles B pulsantes au sein des Nuages de Magellan, galaxies de si faible métallicité que de telles pulsations n'y étaient pas attendues d'un point de vue théorique. Les pulsations de ces étoiles B sont en effet sensibles à la composition chimique car elles sont activées par le mécanisme kappa, lié à la présence d'un pic d'opacité des éléménts du groupe du fer à une température d'environ 200 000K. Dès lors nous étudions le rôle de la composition chimique et des opacités sur ces pulsations, et mettons en évidence une possible sous-estimation des opacités théoriques. Dans ce cadre, nous présentons les efforts récents du projet OPAC portant sur l'étude des opacités des éléments du groupe du fer, pour des conditions similaires aux enveloppes radiatives des étoiles B. [moins ▲]

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Voir détailWhat can we learn about gamma Doradus star internal structure from Kepler?
Ouazzani, R-M.; Antoci, V.; Salmon, Sébastien ULiege et al

Communication orale (2015, June)

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Voir détailAsteroseismology of Massive Stars: Some Words of Caution
Noels-Grötsch, Arlette ULiege; Godart, M.; Salmon, Sébastien ULiege et al

in Meynet, Georges; Georgy, Cyril; Groh, Jose (Eds.) et al Proceedings of the International Astronomical Union S307 (2015, January 01)

Although playing a key role in the understanding of the supernova phenomenon, the evolution of massive stars still suffers from uncertainties in their structure, even during their ``quiet'' main sequence ... [plus ▼]

Although playing a key role in the understanding of the supernova phenomenon, the evolution of massive stars still suffers from uncertainties in their structure, even during their ``quiet'' main sequence phase and later on during their subgiant and helium burning phases. What is the extent of the mixed central region? In the local mixing length theory (LMLT) frame, are there structural differences using Schwarzschild or Ledoux convection criterion? Where are located the convective zone boundaries? Are there intermediate convection zones during MS and post-MS phase, and what is their extent and location? We discuss these points and show how asteroseismology could bring some light on these questions. [moins ▲]

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