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297 results on '"Dupret, M.-A."'

255. g-mode pulsations in slowly pulsating B stars

Author

De Cat, P., primary, Daszyńska-Daszkiewicz, J., additional, Briquet, M., additional, Dupret, M.-A., additional, Scuflaire, R., additional, De Ridder, J., additional, Niemczura, E., additional, and Aerts, C., additional

Published
2004
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257. Seismic modelling of the $\beta\,$Cep star EN (16) Lacertae

Author

Thoul, A., primary, Aerts, C., additional, Dupret, M. A., additional, Scuflaire, R., additional, Korotin, S. A., additional, Egorova, I. A., additional, Andrievsky, S. M., additional, Lehmann, H., additional, Briquet, M., additional, De Ridder, J., additional, and Noels, A., additional

Published
2003
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261. New light on the driving mechanism in roAp stars

Author

Théado, S., Dupret, M.-A., Noels, A., Ferguson, J. W., Théado, S., Dupret, M.-A., Noels, A., and Ferguson, J. W.

Abstract

Context. Observations suggest that a relationship exists between the driving mechanism of roAp star pulsations and the heavy element distribution in these stars.

Published
2009
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265. Modeling the excitation of acoustic modes in αCentauri A

Author

Samadi, R., Belkacem, K., Goupil, M. J., Dupret, M.-A., Kupka, F., Samadi, R., Belkacem, K., Goupil, M. J., Dupret, M.-A., and Kupka, F.

Abstract

From different seismic observations we infer the energy supplied per unit of time by turbulent convection to the acoustic modes of αCentauri A (HD 128620), a star that is similar but not identical to the Sun. The inferred rates of energy supplied to the modes (i.e. mode excitation rates) are found to be significantly higher than in the Sun. They are compared with those computed with an excitation model that includes two sources of driving, the Reynolds stress contribution and the advection of entropy fluctuations. The model also uses a closure model, the Closure Model with Plumes (CMP hereafter), that takes the asymmetry between the up- and down-flows (i.e. the granules and plumes, respectively) into account. Different prescriptions for the eddy-time correlation function are also compared to observational data. Calculations based on a Gaussian eddy-time correlation underestimate excitation rates compared with the values derived from observations for αCentauri A. On the other hand, calculations based on a Lorentzian eddy-time correlation lie within the observational error bars. This confirms results in the solar case. Compared to the helioseismic data, those obtained for αCentauri A constitute an additional support for our model of excitation. We show that mode masses must be computed taking turbulent pressure into account. Finally, we emphasize the need for more accurate seismic measurements in order to distinguish between the CMP closure model and the quasi-normal approximation in the case of αCentauri A, as well as to confirm or not the need to include the excitation by the entropy fluctuations.

Published
2008
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266. Long term photometric monitoring with the Mercator telescope***

Author

De Cat, P., Briquet, M., Aerts, C., Goossens, K., Saesen, S., Cuypers, J., Yakut, K., Scuflaire, R., Dupret, M.-A., Uytterhoeven, K., Van Winckel, H., Raskin, G., Davignon, G., Le Guillou, L., Van Malderen, R., Reyniers, M., Acke, B., De Meester, W., Vanautgaerden, J., Vandenbussche, B., Verhoelst, T., Waelkens, C., Deroo, P., Reyniers, K., Ausseloos, M., Broeders, E., Daszyńska-Daskiewicz, J., Debosscher, J., De Ruyter, S., Lefever, K., Decin, G., Kolenberg, K., Mazumdar, A., Van Kerckhoven, C., De Ridder, J., Drummond, R., Barban, C., Vanhollebeke, E., Maas, T., Decin, L., De Cat, P., Briquet, M., Aerts, C., Goossens, K., Saesen, S., Cuypers, J., Yakut, K., Scuflaire, R., Dupret, M.-A., Uytterhoeven, K., Van Winckel, H., Raskin, G., Davignon, G., Le Guillou, L., Van Malderen, R., Reyniers, M., Acke, B., De Meester, W., Vanautgaerden, J., Vandenbussche, B., Verhoelst, T., Waelkens, C., Deroo, P., Reyniers, K., Ausseloos, M., Broeders, E., Daszyńska-Daskiewicz, J., Debosscher, J., De Ruyter, S., Lefever, K., Decin, G., Kolenberg, K., Mazumdar, A., Van Kerckhoven, C., De Ridder, J., Drummond, R., Barban, C., Vanhollebeke, E., Maas, T., and Decin, L.

Abstract

Aims.We selected a large sample of O-B stars that were considered as (candidate) slowly pulsating B, βCep, and Maia stars after the analysis of their hipparcosdata. We analysed our new seven passband genevadata collected for these stars during the first three years of scientific operations of the mercatortelescope. We performed a frequency analysis for 28 targets with more than 50 high-quality measurements to improve their variability classification. For the pulsating stars, we tried both to identify the modes and to search for rotationally split modes.

Published
2007
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267. Asteroseismology of the new multiperiodic γDor variable HD 239276

Author

Rodríguez, E., Costa, V., Zhou, A.-Y., Grigahcène, A., Dupret, M. A., Suárez, J. C., Moya, A., López-González, M. J., Wei, J.-Y., Fan, Y., Rodríguez, E., Costa, V., Zhou, A.-Y., Grigahcène, A., Dupret, M. A., Suárez, J. C., Moya, A., López-González, M. J., Wei, J.-Y., and Fan, Y.

Abstract

The variability of HD 239276 was suspected photometrically nearly twenty years ago, but was confirmed with new observations obtained in 2001 during a two-site photometric campaign carried out from Spain, in uvbyβStrömgren-Crawford photometry, and China, using the Johnson Vfilter. Two low-dispersion spectra were also collected. The results establish this star as a new multiperiodic γDor-type pulsator with deficiency in metallicity. Its possible λBoo nature is discussed. The frequency analysis shows three pulsational frequencies as significant, but some more are probably present among the residuals. The method based on phase shifts and amplitude ratios in multicolour photometry is used to identify the excited modes with non-adiabatic time-dependent convection models. A very good agreement between the theoretical and observed amplitude ratios is obtained and the two main modes are identified as $l=1$modes. Nevertheless, our results do not allow us to discriminate between a solar abundance and a metal deficient nature for this star. The frequency ratio method is further used for the identification of the modes. The results suggest low metallicity for this star, but a λBoo nature may be not ruled out.

Published
2006
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268. The frequency ratio method and the new multiperiodic γDoradus star HD 218427

Author

Rodríguez, E., Amado, P. J., Suárez, J. C., Moya, A., Dupret, M. A., Poretti, E., Grigahcène, A., Costa, V., López-González, M. J., Rodríguez, E., Amado, P. J., Suárez, J. C., Moya, A., Dupret, M. A., Poretti, E., Grigahcène, A., Costa, V., and López-González, M. J.

Abstract

Oscillations of γDor-type were discovered in the star HD 218427 through simultaneous uvbyphotometric observations carried out in the year 2003. A few H$_{\beta}$-Crawford measurements were also collected for calibration purposes and they locate this star well inside the γDor instability region. We find HD 218427 to be deficient in metals, similar to other well-defined γDor stars, and discuss the possibility that it has a λBoo nature. We carried out frequency analysis for different filters, including the combined “vby” filter, and five frequencies were found as significant with periods ranging between 0.3 and 0.8 days. The recently-developed frequency ratio method is used in order to identify the excited modes. The results are consistent with an $l=2$identification for all the modes and with high radial quantum numbers ($n\sim40$) for the three main observed periodicities. The possibility of multiplet structures is also discussed. However, no consistency is found when using the time-dependent convection treatment to discriminate modes. This disagreement can be due to the large rotation velocity taking place in HD 218427 and, consequently, the significant coupling between the modes.

Published
2006
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270. Non-adiabatic theoretical observables in δScuti stars

Author

Moya, A., Garrido, R., Dupret, M. A., Moya, A., Garrido, R., and Dupret, M. A.

Abstract

Phase differences and amplitude ratios at different colour photometric bands are currently being used to discriminate pulsation modes to facilitate mode identification of κ-driven non-radial pulsating stars. In addition to physical inputs (e.g., mass, Teff, etc.), these quantities depend on the non-adiabatic treatment of the atmosphere. This paper presents theoretical results concerning δScuti pulsating stars. The envelope of each of these stellar structures possesses a convection zone whose development is determined by various factors. An interacting pulsation-atmosphere physical treatment is introduced which supplies two basic non-adiabatic physical quantities: the relative effective temperature variation and the phase lag $\phi^{\rm T}$, defined as the angle between effective temperature variation and radial displacement. These quantities can be used to derive the phase differences and amplitude ratios. Numerical values for these quantities depend critically on the αMLT parameter used to calculate the convection in the envelope. The dependence on αwas analyzed and it was found that the use of colour observations may be of considerable importance in testing the MLT. Finally, examples are given of how αintroduces uncertainties in the theoretical predictions regarding phases and amplitudes of photometric variations in δScuti pulsating stars.

Published
2004
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271. Theoretical instability strips for δScuti and γDoradus stars

Author

Dupret, M.-A., Grigahcène, A., Garrido, R., Gabriel, M., Scuflaire, R., Dupret, M.-A., Grigahcène, A., Garrido, R., Gabriel, M., and Scuflaire, R.

Abstract

New theoretical instability strips for δSct and γDor stars are presented. These results have been obtained taking into account the perturbation of the convective flux following the treatment of Gabriel ([CITE]). For the first time, the red edge of the δSct instability strip for non-radial modes is obtained. The influence of this time-dependent convection (TDC) on the driving of the γDor gravity modes is investigated. The results obtained for different values of the mixing-length parameter αare compared for the γDor models. A good agreement with observations is found for models with αbetween 1.8 and 2.0.

Published
2004
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272. Influence of non-adiabatic temperature variations on line profile variations of slowly rotating βCep stars and SPBs

Author

Dupret, M.-A., De Ridder, J., Neuforge, C., Aerts, C., Scuflaire, R., Dupret, M.-A., De Ridder, J., Neuforge, C., Aerts, C., and Scuflaire, R.

Abstract

In this study, we compute theoretical line profiles of a non-radially pulsating star, taking the non-adiabatic effects into account. These non-adiabatic effects are especially important in the atmosphere, where the spectral lines are formed, and must be accounted for. In this first paper of the series, we present a new treatment of the perturbed thermal and dynamical equations in the atmosphere of a pulsating star. We apply our formalism to the computation of non-adiabatic eigenfunctions in a typical βCephei star with low order p-modes and in a typical slowly pulsating B star with high-order g-modes.

Published
2002
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273. Influence of non-adiabatic temperature variations on line profile variations of slowly rotating βCephei stars and SPBs*

Author

De Ridder, J., Dupret, M.-A., Neuforge, C., Aerts, C., De Ridder, J., Dupret, M.-A., Neuforge, C., and Aerts, C.

Abstract

We investigate to what extent non-adiabatic temperature variations at the surface of slowly rotating non-radially pulsating βCephei stars and slowly pulsating B stars affect silicon line profile variations. We use the non-adiabatic amplitudes of the effective temperature and gravity variation presented in Dupret et al. ([CITE]), together with a Kurucz intensity grid, to compute time series of line profile variations. Our simulations point out that the line shapes do not change significantly due to temperature variations. We find equivalent width variations of at most two percent of the mean equivalent width. We confront our results with observational equivalent width variations and with photometrically obtained effective temperature variations.

Published
2002
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274. Nonradial nonadiabatic stellar pulsations: A numerical method and its application to a βCephei model

Author

Dupret, M. A. and Dupret, M. A.

Abstract

A new general method for the computation of nonradial nonadiabatic oscillations of a given stellar model is presented for a linear approximation. A simple and useful modelling of the atmosphere is included, allowing to obtain credible values for the eigenfunctions in the atmosphere. Some of the results obtained for a $10 M_{\odot}$model are shown as an illustration. Our study opens the way to different applications. Better theoretical line-profile variations could be obtained from our method, allowing a more detailed comparison with observations. More generally, our study is relevant for asteroseismology, giving a way for a better knowledge of stellar interiors.

Published
2001
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275. Calibration of the Pre-Main Sequence Binary System RS Cha: Impact of the Initial Chemical Mixture.

Author

Alecian, E., Lebreton, Y., Goupil, M.-J., Dupret, M.-A., and Catala, C.

Abstract

Accurate observational data are available for the eclipsing double-lined spectroscopic binary system RS Cha, composed of two stars in the pre-main sequence stage of evolution: masses, radii, luminosities and effective temperatures of each component and metallicity of the system. This allows to build pre-main sequence stellar models representing the components of RS Cha and to constrain them in terms of physical ingredients, initial chemical composition and age.We present stellar models we have calculated using the CESAM stellar evolution code for different sets of physical inputs (opacities, nuclear reaction rates, etc.) and different initial parameters (global metallicity, helium abundance, individual abundances of heavy elements). We discuss their ability to reproduce the observational constraints simultaneously for the two components. We focus on the impact on the models of the chemical mixture adopted and we propose a calibration for the RS Cha system providing an estimate of its age and initial helium abundance. [ABSTRACT FROM PUBLISHER]

Published
2008
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276. An asteroseismic study of the β Cephei star θ Ophiuchi: constraints on global stellar parameters and core overshooting.

Author

Briquet, M., Morel, T., Thoul, A., Scuflaire, R., Miglio, A., Montalbán, J., Dupret, M.-A., and Aerts, C.

Subjects
STAR observations, THERMODYNAMIC equilibrium, SPECTRUM analysis, STELLAR activity, STAR formation
Abstract

We present a seismic study of the β Cephei star θ Ophiuchi. Our analysis is based on the observation of one radial mode, one rotationally split triplet and three components of a rotationally split quintuplet for which the m values were well identified by spectroscopy. We identify the radial mode as fundamental, the triplet as p1 and the quintuplet as g1. Our non-local thermodynamic equilibrium abundance analysis results in a metallicity and CNO abundances in full agreement with the most recent updated solar values. With and , and using the Asplund et al. mixture but with a Ne abundance about 0.3 dex larger, the matching of the three independent modes enables us to deduce constrained ranges for the mass and central hydrogen abundance of θ Oph and to prove the occurrence of core overshooting . We also derive an equatorial rotation velocity of . Moreover, we show that the observed non-equidistance of the triplet can be reproduced by the second-order effects of rotation. Finally, we show that the observed rotational splitting of two modes cannot rule out a rigid rotation model. [ABSTRACT FROM AUTHOR]

Published
2007
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278. Time-dependent convection seismic study of fiveγ Doradus stars.

Author

Dupret, M.-A., Grigahcène, A., Garrido, R., De Ridder, J., Scuflaire, R., and Gabriel, M.

Subjects
*CONVECTION (Astrophysics), *ASTROPHYSICS, *HEAT convection, *SEISMOLOGY, *STARS, *GALAXIES
Abstract

We apply for the first time the time-dependent convection (TDC) treatment of Gabriel and Grigahcène et al. to the photometric mode identification inγ Doradus (γ Dor) stars. We consider the influence of this treatment on the theoretical amplitude ratios and phase differences. Comparison with the observed amplitudes and phases of the starsγ Dor, 9 Aurigae, HD 207223= HR 8330, HD 12901 and 48501 is presented and enables us to identify the degreeℓ of the pulsation modes for four of them. We also determine the mode stability for different models of these stars. We show that our TDC models agree better with observations than with frozen convection models. Finally, we compare the results obtained with different values of the mixing-length parameterα. [ABSTRACT FROM AUTHOR]

Published
2005
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279. Stochastic excitation of nonradial modes

Author

Belkacem, K., Samadi, R., Goupil, M., Dupret, M., Brun, A., and Baudin, F.

Abstract

Context. Detection of solar gravity modes remains a major challenge to our understanding of the inner parts of the Sun. Their frequencies would enable the derivation of constraints on the core physical properties, while their amplitudes can put severe constraints on the properties of the inner convective region.Aims. Our purpose is to determine accurate theoretical amplitudes of solar g?modes and estimate the SOHO observation duration for an unambiguous detection of individual modes. We also explain differences in theoretical amplitudes derived from previous works.Methods. We investigate the stochastic excitation of modes by turbulent convection, as well as their damping. Input from a 3D?global simulation of the solar convective zone is used for the kinetic turbulent energy spectrum. Damping is computed using a parametric description of the nonlocal, time-dependent, convection-pulsation interaction. We then provide a theoretical estimation of the intrinsic, as well as apparent, surface velocity.Results. Asymptotic g-mode velocity amplitudes are found to be orders of magnitude higher than previous works. Using a 3D?numerical simulation from the ASH code, we attribute this to the temporal-correlation between the modes and the turbulent eddies, which is found to follow a Lorentzian law rather than a Gaussian one, as previously used. We also find that damping rates of asymptotic gravity modes are dominated by radiative losses, with a typical life time of 3 ?105?years for the ?=1?mode at ?=60?Hz. The maximum velocity in the considered frequency range (10-100??Hz) is obtained for the ?=1 mode at ?=60?Hz and for the ?=2 at ?=100 ?Hz. Due to uncertainties in the modeling, amplitudes at maximum i.e. for ?=1 at?60??Hz can range from?3 to?6?mm?s-1. The upper limit is too high, as g?modes would have been easily detected with SOHO, the GOLF instrument, and this sets an upper constraint mainly on the convective velocity in the Sun.

Published
2009

280. HD?203608, a quiet asteroseismic target in the old galactic disk

Author

Mosser, B., Deheuvels, S., Michel, E., Th?venin, F., Dupret, M., Samadi, R., Barban, C., and Goupil, M.

Abstract

Context. We conducted a 5-night observing run with the spectrometer harps?at the ESO 3.6-m telescope in August 2006, to continue exploring the asteroseismic properties of F-type stars. In fact, Doppler observations of F-type on the main sequence are demanding and remain currently limited to a single case (HD?49933). Comparison with photometric results obtained with the CoRoT space mission (Convection, Rotation and planetary Transits) on similar stars will be possible with an enhanced set of observations.Aims. We selected the 4th magnitude F8V star HD?203608 to investigate the oscillating properties of a low-metallicity star of the old galactic disk.Methods. We reduced the spectra with the on-line data reduction software provided by the instrument. We developed a new statistical approach for extracting the significant peaks in the Fourier domain.Results. The oscillation spectrum shows a significant excess power in the frequency range [1.5, 3.0?mHz]. It exhibits a large spacing of about 120.4??Hz at 2.5?mHz. Variations of the large spacing with frequency are clearly identified, which require an adapted asymptotic development. The modes identification is based on the unambiguous signature of 15 modes with ? = 0 and?1.Conclusions. These observations show the potential diagnostic of asteroseismic constraints. Including them in the stellar modeling significantly enhances the precision on the physical parameters of HD?203608, resulting in a much more precise position in the HR?diagram. The age of the star is now determined in the range 7.25?0.07?Gyr.

Published
2008

281. Stochastic excitation of non-radial modes

Author

Belkacem, K., Samadi, R., Goupil, M.-J., and Dupret, M.-A.

Abstract

Context.Turbulent motions in stellar convection zones generate acoustic energy, part of which is then supplied to normal modes of the star. Their amplitudes result from a balance between the efficiencies of excitation and damping processes in the convection zones. Aims.We develop a formalism that provides the excitation rates of non-radial global modes excited by turbulent convection. As a first application, we estimated the impact of non-radial effects on excitation rates and amplitudes of the high-angular-degree modes that are observed on the Sun. Methods.A model of stochastic excitation by turbulent convection was developed to compute the excitation rates and then successfully applied to solar radial modes. We generalise this approach to the case of non-radial global modes. This enables us to estimate the energy supplied to high-(?) acoustic modes. Qualitative arguments, as well as numerical calculations, are used to illustrate the results. Results.We find that non-radial effects for p?modes are non-negligible: - For high-n modes (i.e. typically n > 3) and for high values of ?, the power supplied to the oscillations depends on the mode inertia. - For low-n?modes, independent of the value of ?, the excitation is dominated by the non-radial components of the Reynolds stress term. Conclusions.Our numerical investigation of high-? p?modes shows that the validity of the present formalism is limited to ? < 500 due to the spatial separation of scale assumption. Thus, a model for very high-? p-mode excitation rates calls for further theoretical developments; however, the formalism is valid for solar g?modes, which will be investigated in a paper in preparation.

Published
2008

282. Time Dependent Convection vs. Frozen Convection Approximations

Author

Grigahc?ne, A., Dupret, M.-A., and Garrido, R.

Abstract

The approximation known as Frozen Convection has been widely used in the context of stellar oscillations due to the lack of a Time Dependent Convection theory. This approximation supposes to neglect the interaction between convection and oscillations and there are different ways to do it. The choice can affect theoretical predictions concerning the non-adiabatic treatment of the stellar oscillations. In fact, fictitious excitation or damping of the pulsation modes can be produced depending on the approximation used.

Published
2007

283. Impact of Transport and Dynamical Processes Upon Stellar Oscillation Frequencies

Author

Goupil, M. and Dupret, M.

Abstract

In order to prepare the theoretical interpretation of the oscillation frequencies detected by CoRoT, comparisons of results from standard stellar models by the ESTA group have proven to be very useful. The next issue which is briefly addressed here is ?what are the additional physical processes that must be included in stellar models computed with different evolutionary codes for the next comparison exercises?? We therefore discuss the impact on oscillation frequencies of several physical processes which are still poorly understood and/or poorly modelled but cannot be fully discarded.

Published
2007

284. Time Dependent Convection vs. Frozen Convection Approximations

Author

Grigahcène, A., Dupret, M.-A., and Garrido, R.

Abstract

The approximation known as Frozen Convection has been widely used in the context of stellar oscillations due to the lack of a Time Dependent Convection theory. This approximation supposes to neglect the interaction between convection and oscillations and there are different ways to do it. The choice can affect theoretical predictions concerning the non-adiabatic treatment of the stellar oscillations. In fact, fictitious excitation or damping of the pulsation modes can be produced depending on the approximation used.

Published
2007
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285. Non-adiabatic study of the Kepler subgiant KIC 6442183.

Author

Grosjean, M., Dupret, M. A., Belkacem, K., Benomar, O., Deheuvels, S., Samadi, R., and Grigahcene, A.

Subjects
*ASTRONOMICAL observations, *SUBGIANT stars, *POWER spectra, *SURFACE properties, *STOCHASTIC processes
Abstract

Thanks to the precision of Kepler observations, [3] were able to measure the linewidth and amplitude of individual modes (including mixed modes) in several subgiant power spectra. We perform a forward modelling of a Kepler subgiant based on surface properties and observed frequencies. Non-adiabatic computations including a time- dependent treatment of convection give the lifetimes of radial and non-radial modes. Next, combining the lifetimes and inertias with a stochastic excitation model gives the amplitudes of the modes. We can now directly compare theoretical and observed linewidths and amplitudes of mixed-modes to obtain new constraints on our theoretical models. [ABSTRACT FROM AUTHOR]

Published
2015
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286. Comprehensive stellar seismic analysis

Author

Farnir, M., Dupret, M-A., Salmon, S.J.A.J., Noels, A., and Buldgen, G.

Subjects
Asteroseismology, Astrophysics::Solar and Stellar Astrophysics, 14. Life underwater, Numerical method, Glitch, Helium abundance
Abstract

Aims: We develop a method that provides a comprehensive analysis of the oscillation spectra of solar-like pulsators. We define new seismic indicators that should be as uncorrelated and as precise as possible and should hold detailed information about stellar interiors. This is essential to improve the quality of the results obtained from asteroseismology as it will provide better stellar models which in turn can be used to refine inferences made in exoplanetology and galactic archeology. Method: The presented method – WhoSGlAd – relies on Gram-Schmidt’s orthogonalisation process. A Euclidean vector subspace of functions is defined and the oscillation frequencies are projected over an orthonormal basis in a specific order. This allows the obtention of independent coefficients that we combine to define independent seismic indicators. Results: The developed method has been shown to be stable and to converge efficiently for solar-like pulsators. Thus, detailed and precise inferences can be obtained on the mass, the age, the chemical composition and the undershooting in the interior of the studied stars. However, attention has to be paid when studying the helium glitch as there seems to be a degeneracy between the influence of the helium abundance and that of the heavy elements on the glitch amplitude. As an example, we analyse the 16CygA (HD 186408) oscillation spectrum to provide an illustration of the capabilities of the method., {"references":["Kjeldsen, H., Bedding, T. R., & Christensen-Dalsgaard, J. 2008, ApJ, 683, L175","Roxburgh, I. W. & Vorontsov, S. V. 2003, A&A, 411, 215","Verma, K., Faria, J. P., Antia, H. M., et al. 2014, ApJ, 790, 138"]}

287. Differential Seismic Modeling of Stars

Author

Ozel, N., Mosser, B., Dupret, M. -A, Bruntt, H., Barban, C., Deheuvels, S., Rafael A. García, Michel, E., Samadi, R., Baudin, F., Régulo, C., Auvergne, M., Baglin, A., Catala, C., Morel, P., and Pichon, B.

288. Comprehensive stellar seismic analysis

Author

Farnir, M., Dupret, M-A., Salmon, S.J.A.J., Noels, A., and Buldgen, G.

Subjects
Asteroseismology, Astrophysics::Solar and Stellar Astrophysics, 14. Life underwater, Numerical method, Glitch, Helium abundance
Abstract

Aims: We develop a method that provides a comprehensive analysis of the oscillation spectra of solar-like pulsators. We define new seismic indicators that should be as uncorrelated and as precise as possible and should hold detailed information about stellar interiors. This is essential to improve the quality of the results obtained from asteroseismology as it will provide better stellar models which in turn can be used to refine inferences made in exoplanetology and galactic archeology. Method: The presented method – WhoSGlAd – relies on Gram-Schmidt’s orthogonalisation process. A Euclidean vector subspace of functions is defined and the oscillation frequencies are projected over an orthonormal basis in a specific order. This allows the obtention of independent coefficients that we combine to define independent seismic indicators. Results: The developed method has been shown to be stable and to converge efficiently for solar-like pulsators. Thus, detailed and precise inferences can be obtained on the mass, the age, the chemical composition and the undershooting in the interior of the studied stars. However, attention has to be paid when studying the helium glitch as there seems to be a degeneracy between the influence of the helium abundance and that of the heavy elements on the glitch amplitude. As an example, we analyse the 16CygA (HD 186408) oscillation spectrum to provide an illustration of the capabilities of the method.

289. The Seismology Programme of CoRoT

Author

Michel, E., Baglin, A., Auvergne, M., Catala, C., Aerts, C., Alecian, G., Pedro José Amado, Appourchaux, T., Ausseloos, M., Ballot, J., Barban, C., Baudin, F., Berthomieu, G., Boumier, P., Bohm, T., Briquet, M., Charpinet, S., Cunha, M. S., Cat, P., Dupret, M. A., Fabregat, J., Floquet, M., Fremat, Y., Garrido, R., Garcia, R. A., Goupil, M. -J, Handler, G., Hubert, A. -M, Janot-Pacheco, E., Lambert, P., Lebreton, Y., Lignieres, F., Lochard, J., Martin-Ruiz, S., Mathias, P., Mazumdar, A., Mittermayer, P., Montalban, J., Monteiro, M. J. P. F. G., Morel, P., Mosser, B., Moya, A., Neiner, C., Nghiem, P., Noels, A., Oehlinger, J., Poretti, E., Provost, J., Renan Medeiros, J., Ridder, J., Rieutord, M., Roca-Cortes, T., Roxburgh, I., Samadi, R., Scuflaire, R., Suarez, J. C., Theado, S., Thoul, A., Toutain, T., Turck-Chieze, S., Uytterhoeven, K., Vauclair, G., Vauclair, S., Weiss, W. W., Zwintz, K., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Instituut voor Sterrenkunde [Leuven], Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Royal Observatory of Belgium [Brussels] (ROB), Observatorio Astronomico de Valencia, Universitat de València (UV), Observatoire de Paris - Site de Meudon (OBSPM), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Instituto de Astronomia, Geofisica e Ciencias Atmosfericas (IAGCAUSP), Universidade de São Paulo (USP), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Institute of Astronomy [Leuven], INAF - Osservatorio Astronomico di Brera (OAB), Istituto Nazionale di Astrofisica (INAF), Institut Non Linéaire de Nice Sophia-Antipolis (INLN), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), Departamento de Fisica (DFUFRG), Universidade Federal do Rio Grande do Norte [Natal] (UFRN), Centro de Investigación Geológica- Guayaquil (CIGG), Petroproducción, Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées (LATT), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Universidade de São Paulo = University of São Paulo (USP), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Royal Observatory of Belgium [Brussels], Universitat de València (UV)-Observatorio Astronomico de Valencia, PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Osservatorio Astronomico di Brera, and Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Space: photometry, pulsation, seismology, Stars: structure
Abstract

International audience; We introduce the main lines and specificities of the CoRoT Seismology Core Programme. The development and consolidation of this programme has been made in the framework of the CoRoT Seismology Working Group. With a few illustrative examples, we show how CoRoT data will help to address various problems associated with present open questions of stellar structure and evolution.

290. First unambiguous asteroseismologic modelling of a gamma Doradus star

Author

Moya, A., Grigahcene, A., Suárez, J. C., Martín-Ruiz, S., Pedro José Amado, Dupret, M. A., Garrido, R., Rodríguez, E., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

291. Are the stars of a new class of variability detected in NGC 3766 fast rotating SPB stars?

Author

Salmon, S. J. A. J., Montalbán, J., Reese, D. R., Dupret, M.-A, Eggenberger, P., Salmon, S. J. A. J., Montalbán, J., Reese, D. R., Dupret, M.-A, and Eggenberger, P.

Abstract

A recent photometric survey in the NGC 3766 cluster led to the detection of stars presenting an unexpected variability. They lie in a region of the Hertzsprung-Russell (HR) diagram where no pulsation are theoretically expected, in between the δ Scuti and slowly pulsating B (SPB) star instability domains. Their variability periods, between ~0.1-0.7 d, are outside the expected domains of these well-known pulsators. The NCG 3766 cluster is known to host fast rotating stars. Rotation can significantly affect the pulsation properties of stars and alter their apparent luminosity through gravity darkening. Therefore we inspect if the new variable stars could correspond to fast rotating SPB stars. We carry out instability and visibility analysis of SPB pulsation modes within the frame of the traditional approximation. The effects of gravity darkening on typical SPB models are next studied. We find that at the red border of the SPB instability strip, prograde sectoral (PS) modes are preferentially excited, with periods shifted in the 0.2-0.5 d range due to the Coriolis effect. These modes are best seen when the star is seen equator-on. For such inclinations, low-mass SPB models can appear fainter due to gravity darkening and as if they were located between the δ Scuti and SPB instability strips

292. Thorough characterisation of the 16 Cygni system

Author

Farnir, M., Dupret, M.-A., Buldgen, G., Salmon, S. J. A. J., Noels, A., Pinçon, C., Pezzotti, C., and Eggenberger, P.

Subjects
QB
Abstract

Context. The advent of space-based photometry observations provided high-quality asteroseismic data for a large number of stars. These observations enabled the adaptation of advanced analyses techniques, until then restricted to the field of helioseismology, to study the best asteroseismic targets. Amongst these, the 16Cyg binary system holds a special place, as they are the brightest solar twins observed by the Kepler mission. For this specific system, modellers have access to high-quality asteroseismic, spectroscopic and interferometric data, making it the perfect testbed for the limitations of stellar models.\ud \ud Aims. We aim to further constrain the internal structure and fundamental parameters of 16CygA&B using linear seismic inversion techniques of both global indicators and localised corrections of the hydrostatic structure.\ud \ud Methods. We start from the models defined by detailed asteroseismic modelling in our previous paper and extend our analysis by applying variational inversions to our evolutionary models. We carried out inversions of so-called seismic indicators and attempted to provide local corrections of the internal structure of the two stars.\ud \ud Results. Our results indicate that linear seismic inversions alone are not able to discriminate between standard and non-standard models for 16CygA&B. We confirm the results of our previous studies that used linear inversion techniques, but consider that the observed differences could be linked to small fundamental parameters variations rather than to a missing process in the models.\ud \ud Conclusions. We confirm the robustness and reliability of the results of the modelling we performed in our previous paper. We conclude that non-linear inversions are likely required to further investigate the properties of 16CygA&B from a seismic point of view, but that these inversions have to be coupled to analyses of the depletion of light elements such as lithium and beryllium to constrain the macroscopic transport of chemicals in these stars and also to constrain potential non-standard evolutionary paths.

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293. Theoretical seismic properties of pre-main sequence γDoradus pulsators

Author

Bouabid, M.-P., Montalbán, J., Miglio, A., Dupret, M.-A., Grigahcène, A., and Noels, A.

Abstract

Context.The late A and F-type γDoradus (γDor) stars pulsate with high-order gravity modes (g-modes). The existence of different evolutionary phases crossing the γDor instability strip raises the question whether pre-main sequence (PMS) γDor stars exist.

Published
2011
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294. The underlying physical meaning of the νmax− νcrelation

Author

Belkacem, K., Goupil, M. J., Dupret, M. A., Samadi, R., Baudin, F., Noels, A., and Mosser, B.

Abstract

Asteroseismology of stars that exhibit solar-like oscillations are enjoying a growing interest with the wealth of observational results obtained with the CoRoT and Kepler missions. In this framework, scaling laws between asteroseismic quantities and stellar parameters are becoming essential tools to study a rich variety of stars. However, the physical underlying mechanisms of those scaling laws are still poorly known. Our objective is to provide a theoretical basis for the scaling between the frequency of the maximum in the power spectrum (νmax) of solar-like oscillations and the cut-off frequency (νc). Using the SoHO GOLF observations together with theoretical considerations, we first confirm that the maximum of the height in oscillation power spectrum is determined by the so-called plateau of the damping rates. The physical origin of the plateau can be traced to the destabilizing effect of the Lagrangian perturbation of entropy in the upper-most layers, which becomes important when the modal period and the local thermal relaxation time-scale are comparable. Based on this analysis, we then find a linear relation between νmaxand νc, with a coefficient that depends on the ratio of the Mach number of the exciting turbulence to the third power to the mixing-length parameter.

Published
2011
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295. HAYDN - High-precision AsteroseismologY of DeNse stellar fields

Author

Giampaolo Piotto, Igor Soszyński, Marc-Antoine Dupret, Frank Grundahl, Valerio Nascimbeni, Demetrio Magrin, Andrea Miglio, Cristina Chiappini, Silvia Toonen, Arlette Noels, Gaël Buldgen, Eline Tolstoy, Eric Michel, William Chantereau, Nadège Lagarde, Amaury H. M. J. Triaud, Bill Chaplin, Karsten Brogaard, Angela Bragaglia, Ted Mackereth, Mark Gieles, Léo Girardi, Georges Meynet, Rob Izzard, Roberto Ragazzoni, Patrick Eggenberger, Benoit Mosser, Nate Bastian, Daisuke Kawata, Josefina Montalbán, Christoffer Karoff, Fiorenzo Vincenzo, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), European Commission, International Space Science Institute, Science and Technology Facilities Council (UK), Swiss National Science Foundation, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Miglio A., Girardi L., Grundahl F., Mosser B., Bastian N., Bragaglia A., Brogaard K., Buldgen G., Chantereau W., Chaplin W., Chiappini C., Dupret M.-A., Eggenberger P., Gieles M., Izzard R., Kawata D., Karoff C., Lagarde N., Mackereth T., Magrin D., Meynet G., Michel E., Montalban J., Nascimbeni V., Noels A., Piotto G., Ragazzoni R., Soszynski I., Tolstoy E., Toonen S., Triaud A., Vincenzo F., and Low Energy Astrophysics (API, FNWI)

Subjects
bulge [Galaxy], Astrophysics::Cosmology and Extragalactic Astrophysics, Globular cluster, low-mass, gGlobular clusters, galaxy: bulge, galaxies: dwarf, asteroseismology [stars], 7. Clean energy, 01 natural sciences, Asteroseismology, Galaxy: bulge, Bulge, low-mass [Stars], Globular clusters, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Stars: low-mass, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, dwarf, Physics, 010308 nuclear & particles physics, Galaxies: dwarf, bulge, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Galaxies, Stars, dwarf [Galaxies], Galaxy, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Miglio, A., et al., In the last decade, the Kepler and CoRoT space-photometry missions have demonstrated the potential of asteroseismology as a novel, versatile and powerful tool to perform exquisite tests of stellar physics, and to enable precise and accurate characterisations of stellar properties, with impact on both exoplanetary and Galactic astrophysics. Based on our improved understanding of the strengths and limitations of such a tool, we argue for a new small/medium space mission dedicated to gathering high-precision, high-cadence, long photometric series in dense stellar fields. Such a mission will lead to breakthroughs in stellar astrophysics, especially in the metal poor regime, will elucidate the evolution and formation of open and globular clusters, and aid our understanding of the assembly history and chemodynamics of the Milky Way’s bulge and a few nearby dwarf galaxies., AM, JM and FV acknowledge support from the European Research Council Consolidator Grant funding scheme (project ASTEROCHRONOMETRY, G.A. n. 772293, http://www.asterochronometry.eu). AM, BM and LG are grateful to the International Space Science Institute (ISSI) for support provided to the asteroSTEP ISSI International Team. AM and WJC acknowledge the support of the UK Science and Technology Facilities Council (STFC). GB is sponsored by the Swiss National Science Foundation (project number 200020 − 172505). WC acknowledges funding from the Swiss National Science Foundation under grant P400P2_183846. We thank G. R. Davies for providing the power spectra used in Fig. 1. N.L. acknowledges financial support from “Programme National de Physique Stellaire” (PNPS) of CNRS/INSU, France. CC acknowledges partial support from DFG Grant CH1188/2-1 and from the ChETEC COST Action (CA16117), supported by COST (European Cooperation in Science and Technology).

Published
2019

296. PLATO as it is: a legacy mission for Galactic archaeology

Author

A. Miglio, C. Chiappini, B. Mosser, G. R. Davies, K. Freeman, L. Girardi, P. Jofré, D. Kawata, B. M. Rendle, M. Valentini, L. Casagrande, W. J. Chaplin, G. Gilmore, K. Hawkins, B. Holl, T. Appourchaux, K. Belkacem, D. Bossini, K. Brogaard, M.‐J. Goupil, J. Montalbán, A. Noels, F. Anders, T. Rodrigues, G. Piotto, D. Pollacco, H. Rauer, C. Allende Prieto, P. P. Avelino, C. Babusiaux, C. Barban, B. Barbuy, S. Basu, F. Baudin, O. Benomar, O. Bienaymé, J. Binney, J. Bland‐Hawthorn, A. Bressan, C. Cacciari, T. L. Campante, S. Cassisi, J. Christensen‐Dalsgaard, F. Combes, O. Creevey, M. S. Cunha, R. S. Jong, P. Laverny, S. Degl'Innocenti, S. Deheuvels, É. Depagne, J. Ridder, P. Di Matteo, M. P. Di Mauro, M.‐A. Dupret, P. Eggenberger, Y. Elsworth, B. Famaey, S. Feltzing, R. A. García, O. Gerhard, B. K. Gibson, L. Gizon, M. Haywood, R. Handberg, U. Heiter, S. Hekker, D. Huber, R. Ibata, D. Katz, S. D. Kawaler, H. Kjeldsen, D. W. Kurtz, N. Lagarde, Y. Lebreton, M. N. Lund, S. R. Majewski, P. Marigo, M. Martig, S. Mathur, I. Minchev, T. Morel, S. Ortolani, M. H. Pinsonneault, B. Plez, P. G. Prada Moroni, D. Pricopi, A. Recio‐Blanco, C. Reylé, A. Robin, I. W. Roxburgh, M. Salaris, B. X. Santiago, R. Schiavon, A. Serenelli, S. Sharma, V. Silva Aguirre, C. Soubiran, M. Steinmetz, D. Stello, K. G. Strassmeier, P. Ventura, R. Ventura, N. A. Walton, C. C. Worley, Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Arizona State University [Tempe] (ASU), Leibniz-Institut für Astrophysik Potsdam (AIP), Department of Physics and Astronomy [Aarhus], Aarhus University [Aarhus], School of Physics and Astronomy [Birmingham], University of Birmingham [Birmingham], Heckscher-Klinikum, Danish AsteroSeismology Centre (DASC), Universidade Federal de São Paulo (UNIFESP), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Department of Astronomy [New Haven], Yale University [New Haven], Evolution et Modélisation des Bassins Sédimentaires (EMBS), Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Department of Biomedical, Metabolic and Neural Sciences [Modena], Chaire Galaxies et cosmologie, Collège de France (CdF (institution)), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universidade de Aveiro, Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Las Cumbres Observatory (LCO), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Université de Strasbourg (UNISTRA), Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universitat de Girona (UdG), Max-Planck-Institut für Extraterrestrische Physik (MPE), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, SETI Institute, University of Illinois at Urbana Champaign (UIUC), University of Illinois at Urbana-Champaign [Urbana], University of Illinois System-University of Illinois System, Universidade Federal de Santa Catarina = Federal University of Santa Catarina [Florianópolis] (UFSC), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Space Science Institute [Boulder] (SSI), Department of Astronomy (Ohio State University), Ohio State University [Columbus] (OSU), Laboratoire Univers et Particules de Montpellier (LUPM), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Astrophysical Research Institute [Liverpool], Liverpool John Moore University (ljmu), Institute of Space Sciences [Barcelona] (ICE-CSIC), Spanish National Research Council [Madrid] (CSIC), Sydney Institute for Astronomy (SIfA), The University of Sydney, M2A 2017, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - 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CRA 1.05.01.94.05, Science and Technology Facilities Council, Programme National Cosmologie et Galaxies (CNRS/INSU, France), IF/00894/2012/, Federación Española de Enfermedades Raras, CNES Fellowship, 615604, ERC Consolidator (STARKEY), Federaal Wetenschapsbeleid, ESP2015-66134-R, Ministerio de Economía y Competitividad, European Commission's Seventh Framework Programme, Swedish National Space Board, European Commission, DLR, FT1400147, Australian Research Council, NNX16AI09G, National Aeronautics and Space Administration, European Cooperation in Science and Technology, CH1188/2-1, DFG, CA16117, ChETEC COST Action, 10118, Villum Fonden, European Union FP7 program, 320360, ERC, UID/FIS/04434/2013, FCT, G1502, NYUAD Institute, Programme National de Physique Stellaire (PNPS), ITA, USA, GBR, FRA, DEU, ESP, Federal University of Sao Paulo (Unifesp), Université Paris-Saclay, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Collège de France - Chaire Galaxies et cosmologie, Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Genève = University of Geneva (UNIGE), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, University of Illinois System, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université des Antilles et de la Guyane (UAG)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles et de la Guyane (UAG)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), Miglio A., Chiappini C., Mosser B., Davies G.R., Freeman K., Girardi L., Jofre P., Kawata D., Rendle B.M., Valentini M., Casagrande L., Chaplin W.J., Gilmore G., Hawkins K., Holl B., Appourchaux T., Belkacem K., Bossini D., Brogaard K., Goupil M.-J., Montalban J., Noels A., Anders F., Rodrigues T., Piotto G., Pollacco D., Rauer H., Prieto C.A., Avelino P.P., Babusiaux C., Barban C., Barbuy B., Basu S., Baudin F., Benomar O., Bienayme O., Binney J., Bland-Hawthorn J., Bressan A., Cacciari C., Campante T.L., Cassisi S., Christensen-Dalsgaard J., Combes F., Creevey O., Cunha M.S., Jong R.S., Laverny P., Degl'Innocenti S., Deheuvels S., Depagne E., Ridder J., Matteo P.D., Mauro M.P.D., Dupret M.-A., Eggenberger P., Elsworth Y., Famaey B., Feltzing S., Garcia R.A., Gerhard O., Gibson B.K., Gizon L., Haywood M., Handberg R., Heiter U., Hekker S., Huber D., Ibata R., Katz D., Kawaler S.D., Kjeldsen H., Kurtz D.W., Lagarde N., Lebreton Y., Lund M.N., Majewski S.R., Marigo P., Martig M., Mathur S., Minchev I., Morel T., Ortolani S., Pinsonneault M.H., Plez B., Moroni P.G.P., Pricopi D., Recio-Blanco A., Reyle C., Robin A., Roxburgh I.W., Salaris M., Santiago B.X., Schiavon R., Serenelli A., Sharma S., Aguirre V.S., Soubiran C., Steinmetz M., Stello D., Strassmeier K.G., Ventura P., Ventura R., Walton N.A., Worley C.C., Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Université Nice Sophia Antipolis (... - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles et de la Guyane (UAG)-Université Pierre et Marie Curie - Paris 6 (UPMC)

Subjects
RED-GIANT STARS, Astrophysics, 01 natural sciences, COROT ASTEROSEISMOLOGY FIELDS, Astrophysics::Solar and Stellar Astrophysics, VELOCITY EXPERIMENT RAVE, Galaxy: structure, 010303 astronomy & astrophysics, SUN-LIKE STAR, QC, QB, Physics, structure - stars: abundances - stars: fundamental parameters - stars: oscillations - surveys [Galaxy], Astrophysics - Solar and Stellar Astrophysics, stars: fundamental parameters, stars: oscillations, Astrophysics::Earth and Planetary Astrophysics, SOLAR-LIKE OSCILLATIONS, THICK DISK, stars: abundances, Relation (database), DATA RELEASE, Milky Way, surveys, Astronomy and Astrophysics, Space and Planetary Science, FOS: Physical sciences, MILKY-WAY DISK, F500, Kepler, Asteroseismology, ATMOSPHERIC PARAMETERS, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Quality (philosophy), Galaxy: structure â stars: abundances â stars: fundamental parameters â stars: oscillations â surveys, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 010308 nuclear & particles physics, Galaxy: structure – stars: abundances – stars: fundamental parameters – stars: oscillations – surveys, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Data science, Astrophysics - Astrophysics of Galaxies, Galaxy, COLD DARK-MATTER, Stars, Astrophysics of Galaxies (astro-ph.GA), Stellar physics, Galaxy: structure – stars: abundances – stars: fundamental parameters – stars: oscillations – surveys, Galaxy: structure - stars: abundances - stars: fundamental parameters - stars: oscillations - surveys
Abstract

Deciphering the assembly history of the Milky Way is a formidable task, which becomes possible only if one can produce high-resolution chrono-chemo-kinematical maps of the Galaxy. Data from large-scale astrometric and spectroscopic surveys will soon provide us with a well-defined view of the current chemo-kinematical structure of the Milky Way, but will only enable a blurred view on the temporal sequence that led to the present-day Galaxy. As demonstrated by the (ongoing) exploitation of data from the pioneering photometric missions CoRoT, Kepler, and K2, asteroseismology provides the way forward: solar-like oscillating giants are excellent evolutionary clocks thanks to the availability of seismic constraints on their mass and to the tight age-initial-mass relation they adhere to. In this paper we identify five key outstanding questions relating to the formation and evolution of the Milky Way that will need precise and accurate ages for large samples of stars to be addressed, and we identify the requirements in terms of number of targets and the precision on the stellar properties that are needed to tackle such questions. By quantifying the asteroseismic yields expected from PLATO for red-giant stars, we demonstrate that these requirements are within the capabilities of the current instrument design, provided that observations are sufficiently long to identify the evolutionary state and allow robust and precise determination of acoustic-mode frequencies. This will allow us to harvest data of sufficient quality to reach a 10% precision in age. This is a fundamental pre-requisite to then reach the more ambitious goal of a similar level of accuracy, which will only be possible if we have to hand a careful appraisal of systematic uncertainties on age deriving from our limited understanding of stellar physics, a goal which conveniently falls within the main aims of PLATO's core science., 17 pages, 9 figures, accepted for publication in Astronomical Notes

Published
2017

297. Modelling displacive and diffusive phase transition in steel

Author

MARALDI, MIRKO, MOLARI, LUISA, MOLARI, PIER GABRIELE, G. N. Wells, F. DUPRET & M. PAPALEXANDRIS, M. Maraldi, L. Molari, P.G. Molari, and G.N.Wells

Subjects
FINITE ELEMENT METHOD, DISPLACIVE TRANSFORMATIONS, THERMODYNAMICS, DIFFUSIVE TRANSFORMATIONS
Abstract

The heat treatment of steels is a process of fundamental importance for manipulating the properties of the steel. We present a consistent thermodynamic framework for modelling the heat treatment process which is able to capture both displacive and diffusive mechanisms. The present formulation is applicable to the a grain size level of observation. Some salient features of the thermodynamic framework are highlighted, especially those associated with surface energies, and a number of numerical experiments are presented.

Published
2009

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