References of "Dupret, Marc-Antoine"
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See detailNon-adiabatic seismic study of the triple system DG Leo
Grigahcène, A.; Suárez, J. C.; Dupret, Marc-Antoine ULg et al

in Tidal Evolution and Oscillations in Binary Stars (2005, November 01)

The interest in studying multiple systems comes from the fact that they give a good number of constraints on their components. From the multiplicity we have constraints on mass and age. Moreover, if one ... [more ▼]

The interest in studying multiple systems comes from the fact that they give a good number of constraints on their components. From the multiplicity we have constraints on mass and age. Moreover, if one or more components of the system show oscillating properties as the DG Leo triple system, additional constraints provided by seismology can be obtained once the modes are identified. In this work, we consider an equilibrium model of the DG Leo system constrained by its multiplicity properties, we attempt to check our new Time Depending Convection treatment on the modes identification of the DG Leo system. [less ▲]

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See detailTime-dependent convection seismic study of delta Sct stars
Dupret, Marc-Antoine ULg; Grigahcène, A.; Garrido, R. et al

in Monthly Notices of the Royal Astronomical Society (2005), 361

We apply for the first time the time-dependent convection (TDC) treatment of Gabriel and Grigahcène et al. to the mode identification and seismic study of delta Sct stars. We consider the influence of ... [more ▼]

We apply for the first time the time-dependent convection (TDC) treatment of Gabriel and Grigahcène et al. to the mode identification and seismic study of delta Sct stars. We consider the influence of this treatment on the photometric amplitude ratios and phase differences, and compare our TDC results to frozen convection (FC) results. We also compare the results obtained with different values of the mixing-length (ML) parameter alpha. Finally, we identify the modes and perform a seismic study of the stars V784 Cassiopeae (Cas), 1 Monocerotis (Mon) and 28 Andromedae (And), and show that our TDC models agree better with observations than FC models. [less ▲]

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See detailTime-dependent convection seismic study of five gamma Doradus stars
Dupret, Marc-Antoine ULg; Grigahcène, A.; Garrido, R. et al

in Monthly Notices of the Royal Astronomical Society (2005), 360

We apply for the first time the time-dependent convection (TDC) treatment of Gabriel and Grigahcène et al. to the photometric mode identification in gamma Doradus (gamma Dor) stars. We consider the ... [more ▼]

We apply for the first time the time-dependent convection (TDC) treatment of Gabriel and Grigahcène et al. to the photometric mode identification in gamma Doradus (gamma 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 stars gamma Dor, 9 Aurigae, HD 207223 = HR 8330, HD 12901 and 48501 is presented and enables us to identify the degree l 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 parameter alpha. [less ▲]

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See detailAsteroseismology of delta Scuti Stars: Problems and Prospects
Goupil, Marie-José; Dupret, Marc-Antoine ULg; Samadi, R. et al

in Journal of Astrophysics & Astronomy (2005), 26

We briefly outline the state-of-the-art seismology of delta Scuti stars from a theoretical point of view: why is it so difficult a task? The recent theoretical advances in the field that these ... [more ▼]

We briefly outline the state-of-the-art seismology of delta Scuti stars from a theoretical point of view: why is it so difficult a task? The recent theoretical advances in the field that these difficulties have influenced are also discussed. [less ▲]

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See detailConvection-pulsation coupling. II. Excitation and stabilization mechanisms in delta Sct and gamma Dor stars
Dupret, Marc-Antoine ULg; Grigahcène, A.; Garrido, R. et al

in Astronomy and Astrophysics (2005), 435

We apply here the Time Dependent Convection (TDC) treatment presented in our earlier paper in this series to the study of delta Sct and gamma Dor pulsating stars. Stabilization of the delta Sct p-modes at ... [more ▼]

We apply here the Time Dependent Convection (TDC) treatment presented in our earlier paper in this series to the study of delta Sct and gamma Dor pulsating stars. Stabilization of the delta Sct p-modes at the red edge of the Instability Strip (IS) and the driving of the gamma Dor g-modes are explained by our models. Theoretical IS obtained with different values of the Mixing Length (ML) parameter alpha are compared to observations and a good agreement is obtained for alpha between 1.8 and 2. The influence of each term of our TDC treatment (perturbation of convective flux, turbulent pressure, and turbulent kinetic energy dissipation) on the eigenfrequencies and on the driving and damping mechanisms is investigated. Finally, we show that our TDC models predict the likely existence of hybrid stars with both delta Sct p-modes and gamma Dor g-modes oscillations. [less ▲]

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See detailConvection-pulsation coupling. I. A mixing-length perturbative theory
Grigahcène, A.; Dupret, Marc-Antoine ULg; Gabriel, Maurice ULg et al

in Astronomy and Astrophysics (2005), 434

We present in details a time-dependent convection treatment in the frame of the Mixing-Length Theory (MLT). Following the original ideas by Unno (1967, PASJ, 19, 140), this theory has been developed by ... [more ▼]

We present in details a time-dependent convection treatment in the frame of the Mixing-Length Theory (MLT). Following the original ideas by Unno (1967, PASJ, 19, 140), this theory has been developed by Gabriel et al. (1974, Bull. Ac. Roy. Belgique, Classe des Sciences, 60, 866) and Gabriel (1996, Bull. Astron. Soc. India, 24, 233). In this paper, we present it in a united form, we detail the basic derivations and approximations and give final improvements. A new perturbation of the energy closure equation is proposed for the first time, making it possible to avoid the occurrence of short wavelength spatial oscillations of the thermal eigenfunctions. This theory accounts for the perturbation of the convective flux, the turbulent Reynolds stress and the turbulent kinetic energy dissipation. It has been numerically implemented in a non-radial non-adiabatic pulsation code and the first results published in a Letter by Dupret et al. (2004a, A&A, 414, L17) indicate that the theory predicts the observed red border of the lower end of the instability strip and the driving mechanism of the recently discovered gamma Dor stars. [less ▲]

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See detailA study of bright southern slowly pulsating B stars. III. Mode identification for singly-periodic targets in spectroscopy
De Cat, P.; Briquet, Maryline ULg; Daszynska-Daszkiewicz, J. et al

in Astronomy and Astrophysics (2005), 432

We present the results of the mode identification for a sample of 7 bright southern slowly pulsating B stars showing one pulsation frequency in the lambdalambda 413 nm Si II profiles. We combined the ... [more ▼]

We present the results of the mode identification for a sample of 7 bright southern slowly pulsating B stars showing one pulsation frequency in the lambdalambda 413 nm Si II profiles. We combined the results from (1) the method of photometric amplitudes; (2) the moment method; and (3) the amplitude and phase variation across the profile to search for the l and m values of the modes best fitting the data. It is the first time that the applicability of these techniques is tested to a sample of main-sequence g-mode pulsators. Combining the moment method with the amplitude and phase variations across the observed line profile gives an improvement in spectroscopic identification of low degree l g-mode pulsations. Using the variations of the higher order even moments < v[SUP]4[/SUP]> and < v[SUP]6[/SUP]> of the moment method solutions can also help. For HD 181558, HD 24587, HD 140873 and HD 177863, the photometric and spectroscopic results are compatible and point towards (l,m) = (1, +1) sectoral modes. For HD 215573, HD 53921 and HD 92287, the results are inconclusive. Our proposed methodology for mode identification is also applicable to gamma Doradus stars. Based on observations collected with the CAT Telescope of the European Southern Observatory and with the Swiss Photometric Telescope of the Geneva Observatory, both situated at La Silla in Chile. [less ▲]

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See detailConvection-Oscillations Interaction in F-G Type Main Sequence Stars
Dupret, Marc-Antoine ULg; Grigahcène, A.; Garrido, R. et al

in SOHO 14 Helio- and Asteroseismology: Towards a Golden Future (2004, October 01)

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See detailTheoretical Instability Strips and Non-Adiabatic Photometric Observables for d Scut and g DOR Stars
Dupret, Marc-Antoine ULg; Grigahcène, A.; Garrido, R. et al

in SOHO 14 Helio- and Asteroseismology: Towards a Golden Future (2004, October 01)

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See detailInfluence of the convective flux perturbation on stellar oscillations: application to Delta Scuti and Gamma Doradus stars
Grigahcene, A.; Dupret, Marc-Antoine ULg; Garrido, R. et al

in Communications in Asteroseismology (2004), 145

We present a theory of convection-oscillation interaction. In our nonradial nonadiabatic pulsation code, the variation of the convective flux (radial and transversal components) is taken into account ... [more ▼]

We present a theory of convection-oscillation interaction. In our nonradial nonadiabatic pulsation code, the variation of the convective flux (radial and transversal components) is taken into account, following the theory of M. Gabriel, within the mixing length approach. We explore the influence of the convective flux variation on mode stability near the red-edge of the Delta Scuti instability strip and the excitation mechanisms of Gamma Doradus stars. [less ▲]

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See detailg-mode pulsations in slowly pulsating B stars
De Cat, P.; Daszynska-Daszkiewicz, J.; Briquet, Maryline ULg et al

in IAU Colloq. 193: Variable Stars in the Local Group (2004, May 01)

In this paper, we give an updated overview of the observed characteristics of g-mode pulsations in slowly pulsating B stars. These characteristics are based on the combined results of linear nonadiabatic ... [more ▼]

In this paper, we give an updated overview of the observed characteristics of g-mode pulsations in slowly pulsating B stars. These characteristics are based on the combined results of linear nonadiabatic analysis of the oscillations and a photometric and spectroscopic mode identification for a sample of 13 members. For 4 stars, at least one mode is stable in all the considered theoretical models. [less ▲]

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See detailNon-adiabatic seismic study of the thin convective envelope of delta Scuti stars
Dupret, Marc-Antoine ULg; Grigahcène, A.; Garrido, R. et al

in IAU Colloq. 193: Variable Stars in the Local Group (2004, May 01)

For delta Sct stars, the theoretical predictions of a non-adiabatic pulsation code are very dependent on the characteristics of the thin convective envelope of the models (Balona and Evers 1999). The ... [more ▼]

For delta Sct stars, the theoretical predictions of a non-adiabatic pulsation code are very dependent on the characteristics of the thin convective envelope of the models (Balona and Evers 1999). The treatment of the non-adiabatic interaction between convection and pulsation also has a significant impact on the results, particularly near the red edge of the instability strip. The non-adiabatic theoretical predictions can be tested upon observations by comparing them to the amplitude ratios and phase differences as observed in different color passbands (Dupret et al. 2003). In the first part of this paper, we compare the results obtained by adopting different treatments of convection in the interior and atmosphere models: mixing-length theory (MLT) and full spectrum of turbulence (FST) (Canuto et al. 1996, CGM). In the second part, we examine the problem of the interaction between convection and pulsation and compare the mode stability obtained with and without including time-dependent convection in our non-adiabatic code. [less ▲]

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See detailNon-adiabatic asteroseismology of near-main sequence variable stars
Dupret, Marc-Antoine ULg

in IAU Colloq. 193: Variable Stars in the Local Group (2004, May 01)

We present in this talk a new linear non-adiabatic pulsation code: MAD[SUP]1[/SUP]. We detail all the possible applications of it in the frame of asteroseismology. By using it, photospheric observables ... [more ▼]

We present in this talk a new linear non-adiabatic pulsation code: MAD[SUP]1[/SUP]. We detail all the possible applications of it in the frame of asteroseismology. By using it, photospheric observables such as multi-color photometric amplitude ratios, phase differences and line profile variations can be determined accurately and confronted with observations. Moreover, MAD enables the precisely analysis of the excitation mechanisms of pulsating stars. Applications to different kinds of variable stars (delta Sct, beta Cephei, Slowly Pulsating B and gamma Dor stars) are presented by Dupret et al. (these proceedings), Handler and Aerts (these proceedings), De Cat et al. (these proceedings) and De Ridder et al. (these proceedings). [less ▲]

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See detailNonadiabatic observables in main sequence delta Scuti stars
Moya, A.; Garrido, R.; Dupret, Marc-Antoine ULg

in IAU Colloq. 193: Variable Stars in the Local Group (2004, May 01)

Using a theoretical nonadiabatic pulsation model, phase differences and amplitude ratios between the relative effective temperature variation and the relative radial displacement have been calculated ... [more ▼]

Using a theoretical nonadiabatic pulsation model, phase differences and amplitude ratios between the relative effective temperature variation and the relative radial displacement have been calculated. These quantities, when compared with photometric observations in different colors, provide an efficient instrument for mode identification, the first step to understand the internal structure of the stars. The theoretical results presented in this paper show a dependence for delta Scuti stars on the mixing length parameter alpha used to treat the convection using the standard Mixing Length Theory. The nonadiabatic pulsational code developed here includes the pulsation atmosphere interaction as described by Dupret et al. (2002). The equilibrium models are provided by the CESAM evolutionary code, where a complete reconstruction of non-grey atmospheres (Kurucz models) is included. [less ▲]

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See detailMode identification using photometry and spectroscopy
De Ridder, Joris; Aerts, Conny; Dupret, Marc-Antoine ULg

in IAU Colloq. 193: Variable Stars in the Local Group (2004, May 01)

We tested a stepwise approach to combine photometry and spectroscopy for mode identificaiton where we first used the photometric amplitude ratios to restrict the degree l, then did a spectroscopic mode ... [more ▼]

We tested a stepwise approach to combine photometry and spectroscopy for mode identificaiton where we first used the photometric amplitude ratios to restrict the degree l, then did a spectroscopic mode identification, and finally fitted the photometric amplitudes to restrict the list of candidate modes. For the spectroscopic mode identification, we implemented an efficient multi-mode moment method variant. We conclude that this new variant works well, but that the photometric amplitudes are too model sensitive to do any additional mode discrimination. [less ▲]

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See detailLong-term multicolour photometry and high-resolution spectroscopy of the two gamma Doradus stars HD 12901 and HD 48501
Aerts, C.; Cuypers, J.; De Cat, P. et al

in Astronomy and Astrophysics (2004), 415

We gathered long-term multicolour Geneva UB[SUB]1[/SUB]BB[SUB]2[/SUB]V[SUB]1[/SUB]VG photometric and high-resolution (R=40 000) spectroscopic data of the two gamma Doradus stars HD 12901 and HD 48501. The ... [more ▼]

We gathered long-term multicolour Geneva UB[SUB]1[/SUB]BB[SUB]2[/SUB]V[SUB]1[/SUB]VG photometric and high-resolution (R=40 000) spectroscopic data of the two gamma Doradus stars HD 12901 and HD 48501. The photometry reveals three frequencies for each of the two stars: f[SUB]1[/SUB]=1.21563 c d[SUP]-1[/SUP], f[SUB]2[/SUB]=1.39594 c d[SUP]-1[/SUP] and f[SUB]3[/SUB]=2.18636 c d[SUP]-1[/SUP] for HD 12901 and f[SUB]1[/SUB]=1.09408 c d[SUP]-1[/SUP], f[SUB]2[/SUB]=1.29054 c d[SUP]-1[/SUP] and f[SUB]3[/SUB]=1.19924 c d[SUP]-1[/SUP] for HD 48501. The photometric amplitude is each time largest in the Geneva B[SUB]1[/SUB] filter and the variations in all the different filters are perfectly in phase within the measurement errors. Mode identification points out that the six modes are all l=1 modes and that the non-adiabatic temperature variations are extremely small, in contradiction to current theoretical predictions. Our spectra show that all the observed frequencies are intrinsic to the stars and cannot be due to binarity. We detect clear line-profile variations at low amplitude (<1 km s[SUP]-1[/SUP]) due to the oscillations of both targets. The estimated v sin i from the spectra are Ë 53 km s[SUP]-1[/SUP] for HD 12901 and Ë 29 km s[SUP]-1[/SUP] for HD 48501. It is at present unclear if the triplet-like structure for HD 48501 is the consequence of rotational splitting or of the large separation expected for high-order gravity modes in the asymptotic regime. Based on observations gathered with the Swiss 0.7 m telescope equipped with the photometer P 7 and with the Swiss 1.2 m Euler telescope equipped with the spectrograph CORALIE, both situated at La Silla, Chile. Reduced data available upon request from the first author. [less ▲]

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See detailAsteroseismology of the beta Cep star HD 129929. I. Observations, oscillation frequencies and stellar parameters
Aerts, C.; Waelkens, C.; Daszynska-Daszkiewicz, J. et al

in Astronomy and Astrophysics (2004), 415

We have gathered and analysed a timeseries of 1493 high-quality multicolour Geneva photometric data of the B3V beta Cep star HD 129929. The dataset has a time base of 21.2 years. The occurrence of a ... [more ▼]

We have gathered and analysed a timeseries of 1493 high-quality multicolour Geneva photometric data of the B3V beta Cep star HD 129929. The dataset has a time base of 21.2 years. The occurrence of a beating phenomenon is evident from the data. We find evidence for the presence of at least six frequencies, among which we see components of two frequency multiplets with an average spacing of Ë 0.0121 c d[SUP]-1[/SUP] which points towards very slow rotation. This result is in agreement with new spectroscopic data of the star and also with previously taken UV spectra. We provide the amplitudes of the six frequencies in all seven photometric filters. The metal content of the star is Z=0.018± 0.004. All these observational results will be used to perform detailed seismic modelling of this massive star in a subsequent paper. Based on data gathered with the Swiss 0.7m telescope equipped with the photometer P7 of the Geneva Observatory and with the FEROS spectrograph attached to the ESO 2.2 m telescope, both situated at La Silla in Chile; the reduced photometric multicolour data are provided in Table 1, which is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/415/241 [less ▲]

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See detailAsteroseismology of the beta Cep star HD 129929. II. Seismic constraints on core overshooting, internal rotation and stellar parameters
Dupret, Marc-Antoine ULg; Thoul, Anne ULg; Scuflaire, Richard ULg et al

in Astronomy and Astrophysics (2004), 415

We perform a detailed seismic study of the beta Cep star HD 129929. Our analysis is based on the recent derivation of six pulsation frequencies. These frequencies are unambiguously identified from the ... [more ▼]

We perform a detailed seismic study of the beta Cep star HD 129929. Our analysis is based on the recent derivation of six pulsation frequencies. These frequencies are unambiguously identified from the seismic modelling and the photometric amplitudes to be the radial fundamental, the l=1, p[SUB]1[/SUB] triplet, two consecutive components of the l=2, g[SUB]1[/SUB] quintuplet. A non-adiabatic analysis allows us to constrain the metallicity of the star to Z \in [0.016, 0.022]. In addition, the fitting of three independent frequencies, two of which correspond to axisymmetric (m=0) modes, allows us to constrain the core overshooting parameter to alpha[SUB]ov[/SUB]=0.10 ± 0.05, as well as the other global parameters of the star. Finally, from the observation of the l=1 triplet and part of the l=2 quintuplet, we derive constraints on the internal rotation of this star. [less ▲]

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See detailNon-adiabatic theoretical observables in delta Scuti stars
Moya, A.; Garrido, R.; Dupret, Marc-Antoine ULg

in Astronomy and Astrophysics (2004), 414

Phase differences and amplitude ratios at different colour photometric bands are currently being used to discriminate pulsation modes to facilitate mode identification of kappa-driven non-radial pulsating ... [more ▼]

Phase differences and amplitude ratios at different colour photometric bands are currently being used to discriminate pulsation modes to facilitate mode identification of kappa-driven non-radial pulsating stars. In addition to physical inputs (e.g., mass, T_eff, etc.), these quantities depend on the non-adiabatic treatment of the atmosphere. This paper presents theoretical results concerning delta Scuti 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[SUP]T[/SUP], defined as the angle between effective temperature variation and radial displacement. These quantities can be used to derive the phase differences and amplitude ratios. Numerivalues for these quantities depend critically on the alpha MLT parameter used to calculate the convection in the envelope. The dependence on alpha was 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 alpha introduces uncertainties in the theoretical predictions regarding phases and amplitudes of photometric variations in delta Scuti pulsating stars. [less ▲]

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See detailNon-adiabatic pulsations in delta Scuti stars
Moya, A.; Garrido, R.; Dupret, Marc-Antoine ULg

in Stellar Structure and Habitable Planet Finding (2004, January 01)

For delta Scuti stars, phase differences and amplitude ratios between the relative effective temperature variation and the relative radial displacement can be derived from multicolor photometric ... [more ▼]

For delta Scuti stars, phase differences and amplitude ratios between the relative effective temperature variation and the relative radial displacement can be derived from multicolor photometric observations. The same quantities can be also calculated from theoretical non-adiabatic pulsation models. We present here these theoretical results, which indicate that non-adiabatic quantities depend on the mixing length parameter alpha used to treat the convection in the standard Mixing Length Theory (MLT). This dependence can be used to test and to constrain, through multicolor observations, the way MLT describes convection in the outermost layers of the star. We will use the equilibrium models provided by the CESAM evolutionary code. The pulsational observables are calculated by using a non-adiabatic pulsation code developed by R. Garridon and A. Moya. In the evolutionary and pulsation codes, a complete reconstruction of the non-grey atmosphere (Kurucz models) is included. The interaction between pulsation and atmosphere, as described by Dupret et al. (2002), is also included in the code. [less ▲]

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