References of "Scuflaire, Richard"
     in
Bookmark and Share    
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 25 (7 ULiège)
Full Text
Peer Reviewed
See detailAsteroseismology of the beta Cep star HD 129929. II. Seismic constraints on core overshooting, internal rotation and stellar parameters
Dupret, Marc-Antoine ULiege; Thoul, Anne ULiege; Scuflaire, Richard ULiege 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 ▲]

Detailed reference viewed: 28 (8 ULiège)
Full Text
Peer Reviewed
See detailHe and Si surface inhomogeneities of four Bp variable stars
Briquet, Maryline ULiege; Aerts, C.; Lüftinger, T. et al

in Astronomy and Astrophysics (2004), 413

We present ground-based multi-colour Geneva photometry and high-resolution spectra of four variable B-type stars: HD 105382, HD 131120, HD 138769 and HD 55522. All sets of data reveal monoperiodic stars ... [more ▼]

We present ground-based multi-colour Geneva photometry and high-resolution spectra of four variable B-type stars: HD 105382, HD 131120, HD 138769 and HD 55522. All sets of data reveal monoperiodic stars. A comparison of moment variations of two spectral lines, one silicon line and one helium line, allows us to exclude the pulsation model as being the cause of the observed variability of the four stars. We therefore delete the four stars from the list of candidate slowly pulsating B stars. We attribute the line-profile variations to non-homogeneous distributions of elements on the stellar surface and we derive abundance maps for both elements on the stellar surface by means of the Doppler Imaging technique. We confirm HD 131120 to be a He-weak star and we classify HD 105382, HD 138769 as new He-weak stars. HD 55522 has the solar helium abundance but the mean abundance value of He varies by 0.8 dex during the stellar rotation. For HD 131120 and HD 105382, helium is enhanced in regions of the stellar surface where silicon is depleted and depleted in regions where silicon is enhanced. Based on observations obtained with the Swiss photometric telescope and ESO's CAT/CES telescope, both situated at La Silla, Chile. Appendix A, Tables 1 and 2 and Figs. 9, 11, 13 are only available in electronic form at http://www.edpsciences.org [less ▲]

Detailed reference viewed: 14 (0 ULiège)
Full Text
Peer Reviewed
See detailTheoretical instability strips for delta Scuti and gamma Doradus stars
Dupret, Marc-Antoine ULiege; Grigahcène, A.; Garrido, R. et al

in Astronomy and Astrophysics (2004), 414

New theoretical instability strips for delta Sct and gamma Dor stars are presented. These results have been obtained taking into account the perturbation of the convective flux following the treatment of ... [more ▼]

New theoretical instability strips for delta Sct and gamma Dor stars are presented. These results have been obtained taking into account the perturbation of the convective flux following the treatment of Gabriel (\cite{Gabriel1996}). For the first time, the red edge of the delta Sct instability strip for non-radial modes is obtained. The influence of this time-dependent convection (TDC) on the driving of the gamma Dor gravity modes is investigated. The results obtained for different values of the mixing-length parameter alpha are compared for the gamma Dor models. A good agreement with observations is found for models with alpha between 1.8 and 2.0. [less ▲]

Detailed reference viewed: 36 (2 ULiège)
Full Text
See detailDerivation of the rotational frequency of massive stars from seismic studies
Aerts, C.; Scuflaire, Richard ULiege; Thoul, Anne ULiege

in Stellar Rotation. 215 (2004)

In this contribution we review the current status of the determination of the rotational frequency in non-radially pulsating B stars, i.e. beta Cep stars and slowly pulsating B stars. Considerable ... [more ▼]

In this contribution we review the current status of the determination of the rotational frequency in non-radially pulsating B stars, i.e. beta Cep stars and slowly pulsating B stars. Considerable progress is currently being made in the understanding of the non-radial oscillations of main-sequence B Stars by means of high-temporal, high-spatial resolution spectroscopic time series. This has led to the detection of frequency multiplets, which are interpreted as rotationally splitted non-radial modes and which allow an accurate determination of the surface rotational frequency in some stars. We outline how our future goal, i.e. the derivation of the internal rotation frequency, can be achieved. [less ▲]

Detailed reference viewed: 16 (5 ULiège)
Full Text
See detailGeneva photometry of HD 129929 (Aerts+, 2004)
Aerts, C.; Waelkens, C.; Daszynska-Daszkiewicz, J. et al

in SIMBAD (2003), 341

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 ~0.0121c/d 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. (1 data file). [less ▲]

Detailed reference viewed: 14 (4 ULiège)
Full Text
Peer Reviewed
See detailA Hare and Hound in a BAG: Asteroseismology of Beta Cephei stars
Thoul, Anne ULiege; Ausseloos, M.; Barban, C. et al

in Communications in Asteroseismology (2003), 143

Several members of the COROT Seismology Working Group (SWG) have performed several ``hare-and-hound'' exercises to prepare the data exploitation of the mission in the past few years. These exercises ... [more ▼]

Several members of the COROT Seismology Working Group (SWG) have performed several ``hare-and-hound'' exercises to prepare the data exploitation of the mission in the past few years. These exercises consist in reproducing a theoretical model on the basis of a light curve obtained from a frequency spectrum computed from an ``unknown'' theoretical model of a solar-like or a Delta Scuti star. Members of the BAG (Belgian Asteroseismology Group) have now shown that such an exercise in the mass range of Beta Cephei stars is extremely convincing, making these stars excellent targets for asteroseismology space missions. [less ▲]

Detailed reference viewed: 35 (8 ULiège)
Full Text
Peer Reviewed
See detailSeismic modelling of the beta Cep star EN (16) Lacertae
Thoul, Anne ULiege; Aerts, C.; Dupret, Marc-Antoine ULiege et al

in Astronomy and Astrophysics (2003), 406(1), 287-292

We perform seismic modelling of the massive beta Cep star EN Lacertae. The starting point of our analysis is the spectroscopic mode identification recently performed. To this, we add a new updated ... [more ▼]

We perform seismic modelling of the massive beta Cep star EN Lacertae. The starting point of our analysis is the spectroscopic mode identification recently performed. To this, we add a new updated photometric mode identification based upon a non-adiabatic description of the eigenfunctions in the outer atmosphere. Both mode identifications agree and this allows us to fine-tune the stellar parameters of EN Lacertae with unprecedented precision. This is done by producing a huge amount of stellar models with different parameters and selecting those that fulfill the frequency values and the mode identification. Our study is the first one of its kind in which a reconcilation between observed pulsational characteristics and theoretical models can be achieved at a level that allows accurate determination of the basic stellar parameters of a massive oscillator. We derive a mass of M=9.62+/- 0.11 M[SUB]sun[/SUB] and an age of 15.7 million years if we assume that convective overshooting does not occur. [less ▲]

Detailed reference viewed: 21 (4 ULiège)
Full Text
Peer Reviewed
See detailAsteroseismology of HD 129929: Core Overshooting and Nonrigid Rotation
Aerts, C.; Thoul, Anne ULiege; Daszynska, J. et al

in Science (2003), 300

We have gathered and analyzed 1493 high-quality multicolor Geneva photometric data taken over 21 years of the B3V star HD 129929. We detect six frequencies, among which appear the effects of rotational ... [more ▼]

We have gathered and analyzed 1493 high-quality multicolor Geneva photometric data taken over 21 years of the B3V star HD 129929. We detect six frequencies, among which appear the effects of rotational splitting with a spacing of ~0.0121 cycles per day, which implies that the star rotates very slowly. A nonadiabatic analysis of the oscillations allows us to constrain the metallicity of the star to Z â [0.017,0.022], which agrees with a similar range derived from spectroscopic data. We provide evidence for the occurrence of core convective overshooting in the star, with alpha[SUB]ov[/SUB] = 0.10 +/- 0.05, and we rule out rigid rotation. [less ▲]

Detailed reference viewed: 17 (6 ULiège)
Full Text
Peer Reviewed
See detailA new seismic analysis of Alpha Centauri
Thoul, Anne ULiege; Scuflaire, Richard ULiege; Noels-Grötsch, Arlette ULiege et al

in Astronomy and Astrophysics (2003), 402(1), 293-297

Models of alpha Cen A & B have been computed using the masses determined by Pourbaix et al. (\cite{Po2002}) and the data derived from the spectroscopic analysis of Neuforge & Magain (\cite{Ne1997}). The ... [more ▼]

Models of alpha Cen A & B have been computed using the masses determined by Pourbaix et al. (\cite{Po2002}) and the data derived from the spectroscopic analysis of Neuforge & Magain (\cite{Ne1997}). The seismological data obtained by Bouchy & Carrier (\cite{Bo2001}, \cite{Bo2002}) do help improve our knowledge of the evolutionary status of the system. All the constraints are satisfied with a model which gives an age of about 6 Gyr for the binary. [less ▲]

Detailed reference viewed: 18 (5 ULiège)
Full Text
Peer Reviewed
See detailSpectroscopic mode identification for the slowly pulsating B star HD 147394
Briquet, Maryline ULiege; Aerts, C.; Mathias, P. et al

in Astronomy and Astrophysics (2003), 401

We present ground-based high-resolution high S/N spectra of the slowly pulsating B star HD 147394. Two frequencies are clearly found in the moments of the Si II 4128-4130 doublet: f[SUB]1[/SUB]=0.8008 c d ... [more ▼]

We present ground-based high-resolution high S/N spectra of the slowly pulsating B star HD 147394. Two frequencies are clearly found in the moments of the Si II 4128-4130 doublet: f[SUB]1[/SUB]=0.8008 c d[SUP]-1[/SUP] and f[SUB]2[/SUB]=0.7813 c d[SUP]-1[/SUP]. The frequency f[SUB]1[/SUB] is also found in the HIPPARCOS data. A third frequency is also present in our spectroscopic data: f[SUB]3[/SUB]=0.7175 c d[SUP]-1[/SUP] or its aliases due to the time sampling. A mode identification is performed by means of a new version of the moment method optimized for multiperiodic signals. It points towards several equivalent solutions of non-axisymmetric l <=3 for all three modes. We have too limited information to perform seismic modelling at this stage, but we do show that the different possibilities for the mode identifications are compatible with pulsational models for SPBs. Based on observations obtained with the spectrograph Aurélie attached to the 1.52-m telescope of the Observatoire de Haute-Provence, France. [less ▲]

Detailed reference viewed: 8 (0 ULiège)
Full Text
Peer Reviewed
See detailSpectroscopic mode identification for the beta Cephei star EN (16) Lacertae
Aerts, C.; Lehmann, H.; Briquet, Maryline ULiege et al

in Astronomy and Astrophysics (2003), 399

We perform for the first time spectroscopic mode identification in the eclipsing binary beta Cephei star EN (16) Lac. This mode identification is based upon a time series of 942 line profiles of the He I ... [more ▼]

We perform for the first time spectroscopic mode identification in the eclipsing binary beta Cephei star EN (16) Lac. This mode identification is based upon a time series of 942 line profiles of the He I lambda lambda 6678 Åline in its spectrum. All three known frequencies f[SUB]1[/SUB], f,SUB>2,/SUB>, f[SUB]3[/SUB] of the star are present in the line-profile variations, but we failed to find additional modes. Using different identification methods we find conclusive evidence for the radial nature of the main mode and for the l=2, m=0 identification of the mode with frequency f[SUB]2[/SUB]. A unique identification of the third mode is not possible from the spectra, but we do derive that l[SUB]3[/SUB]<3. Fits to the amplitude and phase variability of the modes imply a rotation frequency between 0.1 and 0.4 c d[SUP]-1[/SUP]. The star's rotation axis is not aligned with the orbital axis. Based on observations gathered with the coudé spectrograph attached to the 2.0 m reflector telescope at Tautenburg Observatory. [less ▲]

Detailed reference viewed: 15 (5 ULiège)
Full Text
Peer Reviewed
See detailA photometric mode identification method, including an improved non-adiabatic treatment of the atmosphere
Dupret, Marc-Antoine ULiege; De Ridder, J.; De Cat, P. et al

in Astronomy and Astrophysics (2003), 398

We present an improved version of the method of photometric mode identification of Heynderickx et al. (\cite{hey}). Our new version is based on the inclusion of precise non-adiabatic eigenfunctions ... [more ▼]

We present an improved version of the method of photometric mode identification of Heynderickx et al. (\cite{hey}). Our new version is based on the inclusion of precise non-adiabatic eigenfunctions determined in the outer stellar atmosphere according to the formalism recently proposed by Dupret et al. (\cite{dup}). Our improved photometric mode identification technique is therefore no longer dependent on ad hoc parameters for the non-adiabatic effects. It contains the complete physical conditions of the outer atmosphere of the star, provided that rotation does not play a key role. We apply our method to the two slowly pulsating B stars HD 74560 and HD 138764 and to the beta Cephei star EN (16) Lac. Besides identifying the degree l of the pulsating stars, our method is also a tool for improving the knowledge of stellar interiors and atmospheres, by imposing constraints on parameters such as the metallicity and the mixing-length parameter alpha (a procedure we label non-adiabatic asteroseismology). The non-adiabatic eigenfunctions needed for the mode identification are available upon request from the authors. [less ▲]

Detailed reference viewed: 17 (6 ULiège)
See detailVariable Blue Stragglers and the EASE Scenario
Noels-Grötsch, Arlette ULiege; Scuflaire, Richard ULiege; Magain, Pierre ULiege et al

in Thompson, M. J.; Cunha, M. S.; Monteiro, M.J.P.F.G. (Eds.) Asteroseismology Across the HR Diagram (2003)

Detailed reference viewed: 20 (3 ULiège)
Full Text
Peer Reviewed
See detailp-mode Oscillations of alpha Cen A
Thoul, Anne ULiege; Scuflaire, Richard ULiege; Vatovez, B. et al

in Astrophysics & Space Science (2003), 284

Models of alpha Cen A & B have been computed using the masses determined by Pourbaix et al. (2002) and the data derived from the spectroscopic analysis of Neuforge and Magain (1997). The seismological ... [more ▼]

Models of alpha Cen A & B have been computed using the masses determined by Pourbaix et al. (2002) and the data derived from the spectroscopic analysis of Neuforge and Magain (1997). The seismological data obtained by Bouchy and Carrier (2001, 2002) do help improve our knowledge of the evolutionary status of the system. All the constraints are satisfied with a model which gives an age of about 6 Gyr for the binary. [less ▲]

Detailed reference viewed: 32 (6 ULiège)
Full Text
See detailMode Identification and Seismic Modelling of the Cep Star EN(16)Lac
Aerts, C.; Lehmann, H.; Scuflaire, Richard ULiege et al

in Asteroseismology Across the HR Diagram (2003)

Detailed reference viewed: 15 (5 ULiège)
Full Text
See detailPhotometric Mode Identification in the Two Doradus Stars HD 12901 and HD 48501
Aerts, C.; Cuypers, J.; Dupret, Marc-Antoine ULiege et al

in Asteroseismology Across the HR Diagram (2003)

Detailed reference viewed: 10 (1 ULiège)
Full Text
Peer Reviewed
See detailAn Improved Method of Photometric Mode Identification: Applications to Slowly Pulsating B, beta Cephei, delta Scuti and gamma Doradus Stars
Dupret, Marc-Antoine ULiege; Scuflaire, Richard ULiege; Noels-Grötsch, Arlette ULiege et al

in Astrophysics & Space Science (2003), 284

We present an improved version of the method of photometric mode identification based upon the inclusion of non-adiabatic eigenfunctions determined in the stellar atmosphere, according to the formalism ... [more ▼]

We present an improved version of the method of photometric mode identification based upon the inclusion of non-adiabatic eigenfunctions determined in the stellar atmosphere, according to the formalism recently proposed by Dupret et al. (2002). We apply our method to beta Cephei, Slowly Pulsating B, delta Scuti and gamma Doradus stars. Besides identifying the degree l of the pulsating stars, our method is also a tool for improving the knowledge of stellar interiors and atmospheres, by imposing constraints on the metallicity for beta Cephei and SPBs, the characteristics of the superficial convection zone for delta Scuti and gamma Doradus stars and the limb-darkening law. [less ▲]

Detailed reference viewed: 29 (3 ULiège)
Full Text
Peer Reviewed
See detailInfluence of non-adiabatic temperature variations on line profile variations of slowly rotating beta Cep stars and SPBs. I. Non-adiabatic eigenfunctions in the atmosphere of a pulsating star
Dupret, Marc-Antoine ULiege; De Ridder, J.; Neuforge, C. et al

in Astronomy and Astrophysics (2002), 385

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 ... [more ▼]

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 beta Cephei star with low order p-modes and in a typical slowly pulsating B star with high-order g-modes. [less ▲]

Detailed reference viewed: 26 (2 ULiège)
Full Text
See detailDetailed Line-Profile Modeling of B Stars with Chemical Inhomogeneities
Briquet, Maryline ULiege; Scuflaire, Richard ULiege; Aerts, C. et al

in Radial and Nonradial Pulsations as Probes of Stellar Physics, ASP Conference Proceedings, Vol. 259. Edited by Conny Aerts, Timothy R. Bedding, and Jørgen Christensen-Dalsgaard. Also IAU Colloquium 185. San Francisco: Astronomical Society of the Pacific, 2002., p.266 (2002)

Detailed reference viewed: 6 (1 ULiège)