Author name code: provost ADS astronomy entries on 2022-09-14 author:"Provost, Janine" ------------------------------------------------------------------------ Title: Detection of g modes in the asymptotic frequency range: evidence for a rapidly rotating core Authors: Ulrich, Roger K.; Fossat, Eric; Boumier, Patrick; Corbard, Thierry; Provost, Janine; Salabert, David; Schmider, François-Xavier; Gabriel, Alan; Grec, Gerard; Renaud, Catherine; Robillot, Jean-Maurice; Roca Cortés, Teodoro; Turck-Chièze, Sylvaine Bibcode: 2017SPD....4810906U Altcode: We present the identification of very low frequency g modes, in the asymptotic regime, and two important parameters: the core rotation rate and the asymptotic equidistant period spacing of these g modes. The GOLF instrument on the SOHO space observatory has provided two decades of full disk helioseismic data. The search for g modes in GOLF measurements has been extremely difficult, due to solar and instrumental noise. In the present study, the p modes of the GOLF signal are analyzed differently, searching for possible collective frequency modulations produced by periodic changes in the deep solar structure. Such modulations provide access to only very low frequency g modes, thus allowing statistical methods to take advantage of their asymptotic properties. For oscillatory periods in the range between 9 and nearly 48 hours, almost 100 g modes of spherical harmonic degree 1 and more than 100 g modes of degree 2 are predicted. They are not observed individually, but when combined, they unambiguously provide their asymptotic period equidistance and rotational splittings, in excellent agreement with the requirements of the asymptotic approximations. P0, the g-mode period equidistance parameter, is measured to be 34 min 01 s, with a 1 s uncertainty. The previously unknown g-mode splittings have now been measured from a non synodic reference with a very high accuracy, and they imply a mean weighted rotation of 1277 ± 10 nHz (9-day period) of their kernels, resulting in a rapid rotation frequency of 1644 ± 23 nHz (period of one week) of the solar core itself, which is a factor 3:8 ± 0:1 faster than the rotation of the radiative envelope.Acknowledgements. Ulrich is first author on this abstract due to AAS rules, Fossat is the actual first author. SOHO is a project of international collaboration between ESA and NASA. We would like to acknowledge the support received continuously during more than 3 decades from CNES. DS acknowledges the financial support from the CNES GOLF grant and the Observatoire de la Côte d’Azur for support during his stays. RKU acknowledges support from NASA for his participation in this project and thanks John Bahcall for enthusiastic encouragement for the g-mode search. Title: Asymptotic g modes: Evidence for a rapid rotation of the solar core Authors: Fossat, E.; Boumier, P.; Corbard, T.; Provost, J.; Salabert, D.; Schmider, F. X.; Gabriel, A. H.; Grec, G.; Renaud, C.; Robillot, J. M.; Roca-Cortés, T.; Turck-Chièze, S.; Ulrich, R. K.; Lazrek, M. Bibcode: 2017A&A...604A..40F Altcode: 2017arXiv170800259F Context. Over the past 40 years, helioseismology has been enormously successful in the study of the solar interior. A shortcoming has been the lack of a convincing detection of the solar g modes, which are oscillations driven by gravity and are hidden in the deepest part of the solar body - its hydrogen-burning core. The detection of g modes is expected to dramatically improve our ability to model this core, the rotational characteristics of which have, until now, remained unknown.
Aims: We present the identification of very low frequency g modes in the asymptotic regime and two important parameters that have long been waited for: the core rotation rate, and the asymptotic equidistant period spacing of these g modes.
Methods: The GOLF instrument on board the SOHO space observatory has provided two decades of full-disk helioseismic data. The search for g modes in GOLF measurements has been extremely difficult because of solar and instrumental noise. In the present study, the p modes of the GOLF signal are analyzed differently: we search for possible collective frequency modulations that are produced by periodic changes in the deep solar structure. Such modulations provide access to only very low frequency g modes, thus allowing statistical methods to take advantage of their asymptotic properties.
Results: For oscillatory periods in the range between 9 and nearly 48 h, almost 100 g modes of spherical harmonic degree 1 and more than 100 g modes of degree 2 are predicted. They are not observed individually, but when combined, they unambiguously provide their asymptotic period equidistance and rotational splittings, in excellent agreement with the requirements of the asymptotic approximations. When the period equidistance has been measured, all of the individual frequencies of each mode can be determined. Previously, p-mode helioseismology allowed the g-mode period equidistance parameter P0 to be bracketed inside a narrow range, between approximately 34 and 35 min. Here, P0 is measured to be 34 min 01 s, with a 1 s uncertainty. The previously unknown g-mode splittings have now been measured from a non-synodic reference with very high accuracy, and they imply a mean weighted rotation of 1277 ± 10 nHz (9-day period) of their kernels, resulting in a rapid rotation frequency of 1644 ± 23 nHz (period of one week) of the solar core itself, which is a factor 3.8 ± 0.1 faster than the rotation of the radiative envelope.
Conclusions: The g modes are known to be the keys to a better understanding of the structure and dynamics of the solar core. Their detection with these precise parameters will certainly stimulate a new era of research in this field. Title: Evolution of lithium abundance in the Sun and solar twins Authors: Thévenin, F.; Oreshina, A. V.; Baturin, V. A.; Gorshkov, A. B.; Morel, P.; Provost, J. Bibcode: 2017A&A...598A..64T Altcode: 2016arXiv161201331T Evolution of the 7Li abundance in the convection zone of the Sun during different stages of its life time is considered to explain its low photospheric value in comparison with that of the solar system meteorites. Lithium is intensively and transiently burned in the early stages of evolution (pre-main sequence, pMS) when the radiative core arises, and then the Li abundance only slowly decreases during the main sequence (MS). We study the rates of lithium burning during these two stages. In a model of the Sun, computed ignoring pMS and without extra-convective mixing (overshooting) at the base of the convection zone, the lithium abundance does not decrease significantly during the MS life time of 4.6 Gyr. Analysis of helioseismic inversions together with post-model computations of chemical composition indicates the presence of the overshooting region and restricts its thickness. It is estimated to be approximately half of the local pressure scale height (0.5HP) which corresponds to 3.8% of the solar radius. Introducing this extra region does not noticeably deplete lithium during the MS stage. In contrast, at the pMS stage, an overshooting region with a value of approximately 0.18HP is enough to produce the observed lithium depletion. If we conclude that the dominant lithium burning takes place during the pMS stage, the dispersion of the lithium abundance in solar twins is explained by different physical conditions, primarily during the early stage of evolution before the MS. Title: a Brief History of the Energy-Momentum Tensor: 1900-1912 Authors: Provost, J. -P. Bibcode: 2015mgm..conf.2054P Altcode: A critical look at the history of relativistic dynamics. Title: Asymptotic and measured large frequency separations Authors: Mosser, B.; Michel, E.; Belkacem, K.; Goupil, M. J.; Baglin, A.; Barban, C.; Provost, J.; Samadi, R.; Auvergne, M.; Catala, C. Bibcode: 2013A&A...550A.126M Altcode: 2012arXiv1212.1687M Context. With the space-borne missions CoRoT and Kepler, a large amount of asteroseismic data is now available and has led to a variety of work. So-called global oscillation parameters are inferred to characterize the large sets of stars, perform ensemble asteroseismology, and derive scaling relations. The mean large separation is such a key parameter, easily deduced from the radial-frequency differences in the observed oscillation spectrum and closely related to the mean stellar density. It is therefore crucial to measure it with the highest accuracy in order to obtain the most precise asteroseismic indices.
Aims: As the conditions of measurement of the large separation do not coincide with its theoretical definition, we revisit the asymptotic expressions used for analyzing the observed oscillation spectra. Then, we examine the consequence of the difference between the observed and asymptotic values of the mean large separation.
Methods: The analysis is focused on radial modes. We use series of radial-mode frequencies in published analyses of stars with solar-like oscillations to compare the asymptotic and observational values of the large separation. This comparison relies on the proper use of the second-order asymptotic expansion.
Results: We propose a simple formulation to correct the observed value of the large separation and then derive its asymptotic counterpart. The measurement of the curvature of the radial ridges in the échelle diagram provides the correcting factor. We prove that, apart from glitches due to stellar structure discontinuities, the asymptotic expansion is valid from main-sequence stars to red giants. Our model shows that the asymptotic offset is close to 1/4, as in the theoretical development, for low-mass, main-sequence stars, subgiants and red giants.
Conclusions: High-quality solar-like oscillation spectra derived from precise photometric measurements are definitely better described with the second-order asymptotic expansion. The second-order term is responsible for the curvature observed in the échelle diagrams used for analyzing the oscillation spectra, and this curvature is responsible for the difference between the observed and asymptotic values of the large separation. Taking it into account yields a revision of the scaling relations, which provides more accurate asteroseismic estimates of the stellar mass and radius. After correction of the bias (6% for the stellar radius and 3% for the mass), the performance of the calibrated relation is about 4% and 8% for estimating, respectively, the stellar radius and the stellar mass for masses less than 1.3 M⊙; the accuracy is twice as bad for higher mass stars and red giants.

Table 1 is available in electronic form at http://www.aanda.org Title: Low frequency signal in the GOLF measurements Authors: Grec, G.; Provost, J.; Renaud, C. Bibcode: 2011JPhCS.271a2050G Altcode: This paper shows the results obtained using a revisited method to normalize the velocity evaluation extracted from the measurements, for roughly 14 years of GOLF data. For the search of g modes, we calculate the low frequency power spectrum of the signal with 2 different approaches: • The classical calculation of the power spectrum of the velocity signal. • An alternative calculation, extracting first the variations along the time of the p-mode frequencies, then calculating the power spectrum of those frequency modulation [4]. Both spectra are compared to the g-mode frequency spectrum calculated for a solar model. Several observed frequencies are in close agreement with the calculated g modes. A careful statistical analysis of this result should now follow. Title: Open issues in probing interiors of solar-like oscillating main sequence stars: 2. Diversity in the HR diagram Authors: Goupil, M. J.; Lebreton, Y.; Marques, J. P.; Deheuvels, S.; Benomar, O.; Provost, J. Bibcode: 2011JPhCS.271a2032G Altcode: 2011arXiv1102.0252G We review some major open issues in the current modelling of low and intermediate mass, main sequence stars based on seismological studies. The solar case was discussed in a companion paper, here several issues specific to other stars than the Sun are illustrated with a few stars observed with CoRoT and expectations from Kepler data. Title: Implications of a new triple-α nuclear reaction rate. Consequences for Cepheids Authors: Morel, P.; Provost, J.; Pichon, B.; Lebreton, Y.; Thévenin, F. Bibcode: 2010A&A...520A..41M Altcode: Context. Recently the triple-α reaction rate has been re-evaluated. In the temperature range, 107-108 K, with respect to the NACRE rate, the new rate is enhanced by up to 20 orders-magnitude.
Aims: To validate this new rate, we investigate its consequences for the evolution of Cepheid models.
Methods: The stellar evolutionary tracks are calculated with the CESAM code and displayed in the domain 4-10 M_⊙.
Results: With the new rate, the first dredge-up does not occur. For masses larger than gse 4.5 M_⊙ each evolutionary track crosses the instability strip only once. The luminosities are higher than with the previous rate, then leading to smaller theoretical masses that better agree with the pulsational mass. Conversely, and inconsistently with one century of observations of more than two hundred Cepheids, the temporal derivative of the period keeps a positive sign. Moreover the observed depletions of atmospheric lithium and C/N ratio do not occur. A slight modification of only a few percents of the new nuclear rate allows us however to restore the loops inside the instability strip and the changes of sign of the temporal derivative of periods.
Conclusions: This preliminary work indicates that the new rate may solve some of the long-lasting unsolved theoretical problems of Cepheids. Yet indisputable observations argue against its pertinence. Nonetheless, with regard to its theoretical importance, the triple-α new reaction rate still needs to be confirmed or revisited. Title: Sensitivity of the sub-photospheric flow fields inferred from ring-diagram analysis to the change on the solar model Authors: Zaatri, A.; Provost, J.; Corbard, T.; Roth, M. Bibcode: 2010Ap&SS.328..135Z Altcode: 2007arXiv0704.2294Z; 2009Ap&SS.tmp..200Z We study the effect of the change of solar model parameters on the measurements of the horizontal velocity flow components based on the analysis of high-degree modes using the ring-diagram local helioseismic technique. We show that changing the equation of state, opacities, surface heavy-element abundances or the modeling of convection do not affect the sub-photospheric flow field measurements. However, the modeling of outermost layers can affect the measurements if an important amount of high radial order modes (high-frequency modes) are included in the analysis. Title: A Multi-Site Campaign to Measure Solar-Like Oscillations in Procyon. II. Mode Frequencies Authors: Bedding, Timothy R.; Kjeldsen, Hans; Campante, Tiago L.; Appourchaux, Thierry; Bonanno, Alfio; Chaplin, William J.; Garcia, Rafael A.; Martić, Milena; Mosser, Benoit; Butler, R. Paul; Bruntt, Hans; Kiss, László L.; O'Toole, Simon J.; Kambe, Eiji; Ando, Hiroyasu; Izumiura, Hideyuki; Sato, Bun'ei; Hartmann, Michael; Hatzes, Artie; Barban, Caroline; Berthomieu, Gabrielle; Michel, Eric; Provost, Janine; Turck-Chièze, Sylvaine; Lebrun, Jean-Claude; Schmitt, Jerome; Bertaux, Jean-Loup; Benatti, Serena; Claudi, Riccardo U.; Cosentino, Rosario; Leccia, Silvio; Frandsen, Søren; Brogaard, Karsten; Glowienka, Lars; Grundahl, Frank; Stempels, Eric; Arentoft, Torben; Bazot, Michaël; Christensen-Dalsgaard, Jørgen; Dall, Thomas H.; Karoff, Christoffer; Lundgreen-Nielsen, Jens; Carrier, Fabien; Eggenberger, Patrick; Sosnowska, Danuta; Wittenmyer, Robert A.; Endl, Michael; Metcalfe, Travis S.; Hekker, Saskia; Reffert, Sabine Bibcode: 2010ApJ...713..935B Altcode: 2010arXiv1003.0052B We have analyzed data from a multi-site campaign to observe oscillations in the F5 star Procyon. The data consist of high-precision velocities that we obtained over more than three weeks with 11 telescopes. A new method for adjusting the data weights allows us to suppress the sidelobes in the power spectrum. Stacking the power spectrum in a so-called échelle diagram reveals two clear ridges, which we identify with even and odd values of the angular degree (l = 0 and 2, and l = 1 and 3, respectively). We interpret a strong, narrow peak at 446 μHz that lies close to the l = 1 ridge as a mode with mixed character. We show that the frequencies of the ridge centroids and their separations are useful diagnostics for asteroseismology. In particular, variations in the large separation appear to indicate a glitch in the sound-speed profile at an acoustic depth of ~1000 s. We list frequencies for 55 modes extracted from the data spanning 20 radial orders, a range comparable to the best solar data, which will provide valuable constraints for theoretical models. A preliminary comparison with published models shows that the offset between observed and calculated frequencies for the radial modes is very different for Procyon than for the Sun and other cool stars. We find the mean lifetime of the modes in Procyon to be 1.29+0.55 -0.49 days, which is significantly shorter than the 2-4 days seen in the Sun. Title: The quest for the solar g modes Authors: Appourchaux, T.; Belkacem, K.; Broomhall, A. -M.; Chaplin, W. J.; Gough, D. O.; Houdek, G.; Provost, J.; Baudin, F.; Boumier, P.; Elsworth, Y.; García, R. A.; Andersen, B. N.; Finsterle, W.; Fröhlich, C.; Gabriel, A.; Grec, G.; Jiménez, A.; Kosovichev, A.; Sekii, T.; Toutain, T.; Turck-Chièze, S. Bibcode: 2010A&ARv..18..197A Altcode: 2010A&ARv.tmp....1A; 2009arXiv0910.0848A Solar gravity modes (or g modes)—oscillations of the solar interior on which buoyancy acts as the restoring force—have the potential to provide unprecedented inference on the structure and dynamics of the solar core, inference that is not possible with the well-observed acoustic modes (or p modes). The relative high amplitude of the g-mode eigenfunctions in the core and the evanesence of the modes in the convection zone make the modes particularly sensitive to the physical and dynamical conditions in the core. Owing to the existence of the convection zone, the g modes have very low amplitudes at photospheric levels, which makes the modes extremely hard to detect. In this article, we review the current state of play regarding attempts to detect g modes. We review the theory of g modes, including theoretical estimation of the g-mode frequencies, amplitudes and damping rates. Then we go on to discuss the techniques that have been used to try to detect g modes. We review results in the literature, and finish by looking to the future, and the potential advances that can be made—from both data and data-analysis perspectives—to give unambiguous detections of individual g modes. The review ends by concluding that, at the time of writing, there is indeed a consensus amongst the authors that there is currently no undisputed detection of solar g modes. Title: GOLF: Analysis of the Low Frequency Spectrum and Comparison with a Calculated Solar g-Mode Spectrum Authors: Grec, G.; Provost, J.; Renaud, C. Bibcode: 2009ASPC..416..209G Altcode: The detection and identification of the g-mode frequency spectrum has not really been achieved even after 13 yr of continuous measurement. We use here the Global Oscillations at Low Frequencies (GOLF) data to evaluate several types of an analysis using cross spectra. One provides an averaged value of the g-mode splitting, resulting in a core rotation faster than the surface rotation, with Rc < 2Rs. A g-mode frequency table is calculated from a solar model, with the assumption of uniform solar rotation in the radiative zone. We show the results of a template of phase-dependent analysis of the cross spectrum and discuss the comparison of the observations and the model. >From a statistical point of view, the search for a single mode faces serious ambiguities. A global approach seems to be the only realistic approach, but today we remain far from a conclusive measurement of g-mode frequencies. Title: Had the planet Mars not existed: Kepler's equant model and its physical consequences Authors: Bracco, C.; Provost, J. -P. Bibcode: 2009EJPh...30.1085B Altcode: 2009arXiv0906.0484B We examine the equant model for the motion of planets, which was the starting point of Kepler's investigations before he modified it because of Mars observations. We show that, up to first order in eccentricity, this model implies for each orbit a velocity, which satisfies Kepler's second law and Hamilton's hodograph, and a centripetal acceleration with an r-2 dependence on the distance to the Sun. If this dependence is assumed to be universal, Kepler's third law follows immediately. This elementary exercise in kinematics for undergraduates emphasizes the proximity of the equant model coming from ancient Greece with our present knowledge. It adds to its historical interest a didactical relevance concerning, in particular, the discussion of the Aristotelian or Newtonian conception of motion. Title: First asteroseismic results from CoRoT Authors: Michel, E.; Baglin, A.; Weiss, W. W.; Auvergne, M.; Catala, C.; Aerts, C.; Appourchaux, T.; Barban, C.; Baudin, F.; Briquet, M.; Carrier, F.; Degroote, P.; De Ridder, J.; Garcia, R. A.; Garrido, R.; Gutiérrez-Soto, J.; Kallinger, T.; Lefevre, L.; Neiner, C.; Poretti, E.; Samadi, R.; Sarro, L.; Alecian, G.; Andrade, L.; Ballot, J.; Benomar, O.; Berthomieu, G.; Boumier, P.; Charpinet, S.; de Batz, B.; Deheuvels, S.; Dupret, M. -A.; Emilio, M.; Fabregat, J.; Facanha, W.; Floquet, M.; Frémat, Y.; Fridlund, M.; Goupil, M. -J.; Grotsch-Noels, A.; Handler, G.; Huat, A. -L.; Hubert, A. -M.; Janot-Pacheco, E.; Kjeldsen, H.; Lebreton, Y.; Leroy, B.; Martayan, C.; Mathias, P.; Miglio, A.; Montalban, J.; Monteiro, M. J. P. F. G.; Mosser, B.; Provost, J; Regulo, C.; Renan de Medeiros, J.; Ribas, I.; Roca Cortés, T.; Roxburgh, I.; Suso, J.; Thoul, A.; Toutain, T.; Tiphene, D.; Turck-Chieze, S.; Vauclair, S.; Vauclair, G.; Zwintz, K. Bibcode: 2008CoAst.156...73M Altcode: About one year after the end of the first observational run and six months after the first CoRoT data delivery, we comment the data exploitation progress for different types of stars. We consider first results to illustrate how these data of unprecedented quality shed a new light on the field of stellar seismology. Title: A Multisite Campaign to Measure Solar-like Oscillations in Procyon. I. Observations, Data Reduction, and Slow Variations Authors: Arentoft, Torben; Kjeldsen, Hans; Bedding, Timothy R.; Bazot, Michaël; Christensen-Dalsgaard, Jørgen; Dall, Thomas H.; Karoff, Christoffer; Carrier, Fabien; Eggenberger, Patrick; Sosnowska, Danuta; Wittenmyer, Robert A.; Endl, Michael; Metcalfe, Travis S.; Hekker, Saskia; Reffert, Sabine; Butler, R. Paul; Bruntt, Hans; Kiss, László L.; O'Toole, Simon J.; Kambe, Eiji; Ando, Hiroyasu; Izumiura, Hideyuki; Sato, Bun'ei; Hartmann, Michael; Hatzes, Artie; Bouchy, Francois; Mosser, Benoit; Appourchaux, Thierry; Barban, Caroline; Berthomieu, Gabrielle; Garcia, Rafael A.; Michel, Eric; Provost, Janine; Turck-Chièze, Sylvaine; Martić, Milena; Lebrun, Jean-Claude; Schmitt, Jerome; Bertaux, Jean-Loup; Bonanno, Alfio; Benatti, Serena; Claudi, Riccardo U.; Cosentino, Rosario; Leccia, Silvio; Frandsen, Søren; Brogaard, Karsten; Glowienka, Lars; Grundahl, Frank; Stempels, Eric Bibcode: 2008ApJ...687.1180A Altcode: 2008arXiv0807.3794A We have carried out a multisite campaign to measure oscillations in the F5 star Procyon A. We obtained high-precision velocity observations over more than three weeks with 11 telescopes, with almost continuous coverage for the central 10 days. This represents the most extensive campaign so far organized on any solar-type oscillator. We describe in detail the methods we used for processing and combining the data. These involved calculating weights for the velocity time series from the measurement uncertainties and adjusting them in order to minimize the noise level of the combined data. The time series of velocities for Procyon shows the clear signature of oscillations, with a plateau of excess power that is centered at 0.9 mHz and is broader than has been seen for other stars. The mean amplitude of the radial modes is 38.1 +/- 1.3 cm s-1 (2.0 times solar), which is consistent with previous detections from the ground and by the WIRE spacecraft, and also with the upper limit set by the MOST spacecraft. The variation of the amplitude during the observing campaign allows us to estimate the mode lifetime to be 1.5+ 1.9-0.8 days. We also find a slow variation in the radial velocity of Procyon, with good agreement between different telescopes. These variations are remarkably similar to those seen in the Sun, and we interpret them as being due to rotational modulation from active regions on the stellar surface. The variations appear to have a period of about 10 days, which presumably equals the stellar rotation period or, perhaps, half of it. The amount of power in these slow variations indicates that the fractional area of Procyon covered by active regions is slightly higher than for the Sun. Title: Oscillations in Procyon A: First results from a multi-site campaign Authors: Hekker, S.; Arentoft, T.; Kjeldsen, H.; Bedding, T. R.; Christensen-Dalsgaard, J.; Reffert, S.; Bruntt, H.; Butler, R. P.; Kiss, L. L.; O'Toole, S. J.; Kambe, E.; Ando, H.; Izumiura, H.; Sato, B.; Hartmann, M.; Hatzes, A. P.; Appourchaux, T.; Barban, C.; Berthomieu, G.; Bouchy, F.; García, R. A.; Lebrun, J. -C.; Martić, M.; Michel, E.; Mosser, B.; Nghiem, P. A. P.; Provost, J.; Samadi, R.; Thévenin, F.; Turck-Chièze, S.; Bonanno, S. A.; Benatti, S.; Claudi, R. U.; Cosentino, R.; Leccia, S.; Frandsen, S.; Brogaard, K.; Grundahl, F.; Stempels, H. C.; Bazot, M.; Dall, T. H.; Karoff, C.; Carrier, F.; Eggenberger, P.; Sosnowska, D.; Wittenmyer, R. A.; Endl, M.; Metcalfe, T. S. Bibcode: 2008JPhCS.118a2059H Altcode: 2007arXiv0710.3772H Procyon A is a bright F5IV star in a binary system. Although the distance, mass and angular diameter of this star are all known with high precision, the exact evolutionary state is still unclear. Evolutionary tracks with different ages and different mass fractions of hydrogen in the core pass, within the errors, through the observed position of Procyon A in the Hertzsprung-Russell diagram. For more than15 years several different groups have studied the solar-like oscillations in Procyon A to determine its evolutionary state. Although several studies independently detected power excess in the periodogram, there is no agreement on the actual oscillation frequencies yet. This is probably due to either insufficient high-quality data (i.e., aliasing) or due to intrinsic properties of the star (i.e., short mode lifetimes). Now a spectroscopic multi-site campaign using 10 telescopes world-wide (minimizing aliasing effects) with a total time span of nearly 4 weeks (increase the frequency resolution) is performed to identify frequencies in this star and finally determine its properties and evolutionary state. Title: CoRoT Measures Solar-Like Oscillations and Granulation in Stars Hotter Than the Sun Authors: Michel, Eric; Baglin, Annie; Auvergne, Michel; Catala, Claude; Samadi, Reza; Baudin, Frédéric; Appourchaux, Thierry; Barban, Caroline; Weiss, Werner W.; Berthomieu, Gabrielle; Boumier, Patrick; Dupret, Marc-Antoine; Garcia, Rafael A.; Fridlund, Malcolm; Garrido, Rafael; Goupil, Marie-Jo; Kjeldsen, Hans; Lebreton, Yveline; Mosser, Benoît; Grotsch-Noels, Arlette; Janot-Pacheco, Eduardo; Provost, Janine; Roxburgh, Ian W.; Thoul, Anne; Toutain, Thierry; Tiphène, Didier; Turck-Chieze, Sylvaine; Vauclair, Sylvie D.; Vauclair, Gérard P.; Aerts, Conny; Alecian, Georges; Ballot, Jérôme; Charpinet, Stéphane; Hubert, Anne-Marie; Lignières, François; Mathias, Philippe; Monteiro, Mario J. P. F. G.; Neiner, Coralie; Poretti, Ennio; Renan de Medeiros, José; Ribas, Ignasi; Rieutord, Michel L.; Roca Cortés, Teodoro; Zwintz, Konstanze Bibcode: 2008Sci...322..558M Altcode: 2008arXiv0812.1267M Oscillations of the Sun have been used to understand its interior structure. The extension of similar studies to more distant stars has raised many difficulties despite the strong efforts of the international community over the past decades. The CoRoT (Convection Rotation and Planetary Transits) satellite, launched in December 2006, has now measured oscillations and the stellar granulation signature in three main sequence stars that are noticeably hotter than the sun. The oscillation amplitudes are about 1.5 times as large as those in the Sun; the stellar granulation is up to three times as high. The stellar amplitudes are about 25% below the theoretic values, providing a measurement of the nonadiabaticity of the process ruling the oscillations in the outer layers of the stars. Title: NOSC: Nice OScillations Code Authors: Provost, J. Bibcode: 2008Ap&SS.316..135P Altcode: 2007Ap&SS.tmp..432P A short presentation of the Nice OScillations Code (NOSC) and of its general properties is given here. We described the physics and the various numerical tools, that we have developed to check the validity and the internal consistency of the frequency calculations for a given model. We present different examples of adiabatic calculations, with an estimation of the achieved internal consistency and numerical accuracy. Title: The CoRoT evolution and seismic tools activity. Goals and tasks Authors: Lebreton, Y.; Monteiro, M. J. P. F. G.; Montalbán, J.; Moya, A.; Baglin, A.; Christensen-Dalsgaard, J.; Goupil, M. -J.; Michel, E.; Provost, J.; Roxburgh, I. W.; Scuflaire, R.; ESTA Team Bibcode: 2008Ap&SS.316....1L Altcode: 2008arXiv0805.0977L; 2008Ap&SS.tmp..157L The forthcoming data expected from space missions such as CoRoT require the capacity of the available tools to provide accurate models whose numerical precision is well above the expected observational errors. In order to secure that these tools meet the specifications, a team has been established to test and, when necessary, to improve the codes available in the community. The CoRoT Evolution and Seismic Tool Activity (ESTA) has been set up with this mission. Several groups have been involved. The present paper describes the motivation and the organisation of this activity, providing the context and the basis for the presentation of the results that have been achieved so far. This is not a finished task as future even better data will continue to demand more precise and complete tools for asteroseismology. Title: Inter-comparison of the g-, f- and p-modes calculated using different oscillation codes for a given stellar model Authors: Moya, A.; Christensen-Dalsgaard, J.; Charpinet, S.; Lebreton, Y.; Miglio, A.; Montalbán, J.; Monteiro, M. J. P. F. G.; Provost, J.; Roxburgh, I. W.; Scuflaire, R.; Suárez, J. C.; Suran, M. Bibcode: 2008Ap&SS.316..231M Altcode: 2007arXiv0711.2587M; 2008Ap&SS.tmp...49M In order to make asteroseismology a powerful tool to explore stellar interiors, different numerical codes should give the same oscillation frequencies for the same input physics. Any differences found when comparing the numerical values of the eigenfrequencies will be an important piece of information regarding the numerical structure of the code. The ESTA group was created to analyze the non-physical sources of these differences. The work presented in this report is a part of Task 2 of the ESTA group. Basically the work is devoted to test, compare and, if needed, optimize the seismic codes used to calculate the eigenfrequencies to be finally compared with observations. The first step in this comparison is presented here. The oscillation codes of nine research groups in the field have been used in this study. The same physics has been imposed for all the codes in order to isolate the non-physical dependence of any possible difference. Two equilibrium models with different grids, 2172 and 4042 mesh points, have been used, and the latter model includes an explicit modelling of semiconvection just outside the convective core. Comparing the results for these two models illustrates the effect of the number of mesh points and their distribution in particularly critical parts of the model, such as the steep composition gradient outside the convective core. A comprehensive study of the frequency differences found for the different codes is given as well. These differences are mainly due to the use of different numerical integration schemes. The number of mesh points and their distribution are crucial for interpreting the results. The use of a second-order integration scheme plus a Richardson extrapolation provides similar results to a fourth-order integration scheme. The proper numerical description of the Brunt-Väisälä frequency in the equilibrium model is also critical for some modes. This influence depends on the set of the eigenfunctions used for the solution of the differential equations. An unexpected result of this study is the high sensitivity of the frequency differences to the inconsistent use of values of the gravitational constant ( G) in the oscillation codes, within the range of the experimentally determined ones, which differ from the value used to compute the equilibrium model. This effect can provide differences for a given equilibrium model substantially larger than those resulting from the use of different codes or numerical techniques; the actual differences between the values of G used by the different codes account for much of the frequency differences found here. Title: Update on g-mode research Authors: García, R. A.; Jiménez, A.; Mathur, S.; Ballot, J.; Eff-Darwich, A.; Jiménez-Reyes, S. J.; Pallé, P. L.; Provost, J.; Turck-Chièze, S. Bibcode: 2008AN....329..476G Altcode: 2008arXiv0802.4296G Since the beginning of this century we have attended a blooming of the gravity-mode research thanks to the unprecedented quality of the data available, either from space with SoHO, or from the ground-based networks as BiSON or GONG. From the first upper limit of the gravity-mode amplitudes fixed at 10 mm/s at 200 μHz given by Appourchaux et al. (2000), on one hand, a peak was supposed to be a component of the ℓ = 1, n = 1 mixed mode (García et al. 2001a, 2001b; Gabriel et al. 2002) and, on the other hand, a couple of patterns - multiplets - were attributed to gravity modes (Turck-Chièze et al. 2004; Mathur et al. 2007). One of these patterns, found around 220 μHz, could be labeled as the ℓ = 2, n =-3 g mode, which is expected to be the one with the highest surface amplitude (Cox & Guzik 2004). Finally, in 2007, García et al. were able to measure the fingertips of the dipole gravity modes looking for their asymptotic properties. In the present paper we present an update of the recent developments on this subject with special attention to the 220 μHz region, the dipole asymptotic properties and the impact of the incoming g-mode observations on the knowledge of the solar structure and rotation profile. Title: Asteroseismology of Procyon with SOPHIE Authors: Mosser, B.; Bouchy, F.; Martić, M.; Appourchaux, T.; Barban, C.; Berthomieu, G.; Garcia, R. A.; Lebrun, J. C.; Michel, E.; Provost, J.; Thévenin, F.; Turck-Chièze, S. Bibcode: 2008A&A...478..197M Altcode: 2007arXiv0712.1368M Context: This paper reports a 9-night asteroseismic observation program conducted in January 2007 with the new spectrometer sophie at the OHP 193-cm telescope, on the F5 IV-V target Procyon A.
Aims: This first asteroseismic program with sophie was intended to test the performance of the instrument with a bright but demanding asteroseismic target and was part of a multisite network.
Methods: The sophie spectra have been reduced with the data reduction software provided by OHP. The Procyon asteroseismic data were then analyzed with statistical tools. The asymptotic analysis has been conducted considering possible curvature in the échelle diagram analysis.
Results: These observations have proven the efficient performance of sophie used as an asteroseismometer, and succeed in a clear detection of the large spacing. An échelle diagram based on the 54-μHz spacing shows clear ridges. Identification of the peaks exhibits large spacings varying from about 52 μHz to 56 μHz. Outside the frequency range [0.9, 1.0 mHz] where the identification is confused, the large spacing increases at a rate of about dΔν/dn ≃ 0.2 μHz. This may explain some of the different values of the large spacing obtained by previous observations.

Based on observations collected with the sophie échelle spectrometer mounted on the 1.93-m telescope at OHP, France (program 06B.PNPS.BOU); http://www.obs-hp.fr/www/guide/ sophie/sophie-eng.html Table of radial velocity measurements 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/478/197 Title: Abundance Analysis of α, Centauri A Authors: Bigot, L.; Thévenin, F.; Provost, J.; Berthomieu, G. Bibcode: 2008psa..conf..259B Altcode: The α centauri system is a reference in stellar physics. The two components, α Cen A (G2V) and α Cen B (K1V), have been extensively studied because of their proximity (1.3pc) and similarity to the Sun. The discovery of solar-like oscillations (Bouchy & Carrier 2002) and the recent interferometric measurements (Kervella et al. 2003) make this system one of the best constrained and therefore one of the most interesting to test both stellar evolution and atmospheric models. The chemical composition of this metal-rich system is still debated ([Fe/H] ≈ +0.1 to +0.2 dex) and is a source of uncertainty in asteroseismic diagnostics. In this work, we propose to improve the Iron abundance by the use of realistic 3D radiative hydrodynamical (RHD) simulations. We present preliminary results for α Cen A and found significant smaller overabundance. This result agrees well with pulsation data. Title: VizieR Online Data Catalog: Procyon (alpha CMi) radial velocities (Mosser+, 2008) Authors: Mosser, B.; Bouchy, F.; Martic, M.; Appourchaux, T.; Barban, C.; Berthomieu, G.; Garcia, R. A.; Lebrun, J. C.; Michel, E.; Provost, J.; Thevenin, F.; Turck-Chieze, S. Bibcode: 2007yCat..34780197M Altcode: Time series of the radial velocities of Procyon recorder with the echelle spectrometer SOPHIE at Observatoire de Haute Provence in January 2007.

(1 data file). Title: Sensitivity of low degree oscillations to the change in solar abundances Authors: Zaatri, A.; Provost, J.; Berthomieu, G.; Morel, P.; Corbard, T. Bibcode: 2007A&A...469.1145Z Altcode: Context: The most recent determination of the solar chemical composition, using a time-dependent, 3D hydrodynamical model of the solar atmosphere, exhibits a significant decrease of C, N, O abundances compared to their previous values. Solar models that use these new abundances are not consistent with helioseismological determinations of the sound speed profile, the surface helium abundance and the convection zone depth.
Aims: We investigate the effect of changes of solar abundances on low degree p-mode and g-mode characteristics which are strong constraints of the solar core. We consider particularly the increase of neon abundance in the new solar mixture in order to reduce the discrepancy between models using new abundances and helioseismology.
Methods: The observational determinations of solar frequencies from the GOLF instrument are used to test solar models computed with different chemical compositions. We consider in particular the normalized small frequency spacings in the low degree p-mode frequency range.
Results: Low-degree small frequency spacings are very sensitive to changes in the heavy-element abundances, notably neon. We show that by considering all the seismic constraints, including the small frequency spacings, a rather large increase of neon abundance by about (0.5±0.05) dex can be a good solution to the discrepancy between solar models that use new abundances and low degree helioseismology, subject to adjusting slightly the solar age and the highest abundances. We also show that the change in solar abundances, notably neon, considerably affects g-mode frequencies, with relative frequency differences between the old and the new models higher than 1.5%. Title: Tracking Solar Gravity Modes: The Dynamics of the Solar Core Authors: García, Rafael A.; Turck-Chièze, Sylvaine; Jiménez-Reyes, Sebastian J.; Ballot, Jérôme; Pallé, Pere L.; Eff-Darwich, Antonio; Mathur, Savita; Provost, Janine Bibcode: 2007Sci...316.1591G Altcode: Solar gravity modes have been actively sought because they directly probe the solar core (below 0.2 solar radius), but they have not been conclusively detected in the Sun because of their small surface amplitudes. Using data from the Global Oscillation at Low Frequency instrument, we detected a periodic structure in agreement with the period separation predicted by the theory for gravity dipole modes. When studied in relation to simulations including the best physics of the Sun determined through the acoustic modes, such a structure favors a faster rotation rate in the core than in the rest of the radiative zone. Title: Asteroseismology and evolutionary status of Procyon A Authors: Provost, J.; Berthomieu, G.; Martić, M.; Morel, P. Bibcode: 2006A&A...460..759P Altcode: Models of Procyon A satisfying the actual observational constraints, particularly the asteroseismic ones, are discussed. The oscillations of these models were computed and analysed. We looked for seismic signatures of the evolutionary status of Procyon A. We show that the behavior of the small frequency spacings, particularly δν01 allows us to distinguish between main sequence and post-main sequence models, all satisfying the observational constraints on mass, effective temperature, radius, and surface metallicity of Procyon A. We also introduce a new seismic evolution criterion, varepsilon, based on the comparison of the low and high frequency parts of the power spectrum. The comparison of the seismic properties of the models with the available asteroseismic observations does not allow us to definitely decide on the stage of evolution of Procyon A. Much more accurate frequencies must be obtained especially in the low-frequency domain to distinguish between the models. Title: Evaluation of the Scientific Performances for the Seismology Programme Authors: Appourchaux, T.; Berthomieu, G.; Michel, E.; Ballot, J.; Barban, C.; Baudin, F.; Boumier, P.; De Ridder, J.; Floquet, M.; Garcia, R. A.; Garrido, R.; Goupil, M. -J.; Lambert, P.; Lochard, J.; Mazumdar, A.; Neiner, C.; Poretti, E.; Provost, J.; Roxburgh, I.; Samadi, R.; Toutain, T. Bibcode: 2006ESASP1306..429A Altcode: The Data Analysis Team of the Seismology Working Group of COROT performed several hare-and-hound exercises. These exercises aimed at putting the team in a situation as if they would analyze data coming out of the COROT spacecraft. In total the team performed five different exercises simulating solar-like stars (HH#1, HH#2, HH#3), classical pulsators (HH#5), validating seismic calibration of stellar model (HH#2, HH#3) and pushing the limit of detection (HH#4). This paper tries both to serve as a summary and as a portal to other publications of the DAT. Title: Data Analysis Tools for the Seismology Programme Authors: Appourchaux, T.; Berthomieu, G.; Michel, E.; Aerts, C.; Ballot, J.; Barban, C.; Baudin, F.; Boumier, P.; De Ridder, J.; Floquet, M.; Garcia, R. A.; Garrido, R.; Goupil, M. -J.; Lambert, P.; Lochard, J.; Neiner, C.; Poretti, E.; Provost, J.; Roxburgh, I.; Samadi, R.; Toutain, T. Bibcode: 2006ESASP1306..377A Altcode: Tools developed by helioseismologists and by classical-pulsator astronomers have been used in the hare-and-hound exercises for having a several different ways of deriving the oscillation mode parameters such as frequency or amplitude. These tools are used for deriving what we call recipes that will allow us to obtain the mode parameters from light curves either for solar-like stars or for classical pulsators. The recipes are used for tagging the mode parameters as being those of COROT. They will be used as reference or yardstick for other fitting strategies. We will also address the issue of mode detection. Additional tools such as time-frequency analysis will be presented. Title: Report on the CoRoT Evolution and Seismic Tools Activity Authors: Monteiro, M. J. P. F. G.; Lebreton, Y.; Montalban, J.; Christensen-Dalsgaard, J.; Castro, M.; Degl'Innocenti, S.; Moya, A.; Roxburgh, I. W.; Scuflaire, R.; Baglin, A.; Cunha, M. S.; Eggenberger, P.; Fernandes, J.; Goupil, M. J.; Hui-Bon-Hoa, A.; Marconi, M.; Marques, J. P.; Michel, E.; Miglio, A.; Morel, P.; Pichon, B.; Prada Moroni, P. G.; Provost, J.; Ruoppo, A.; Suarez, J. -C.; Suran, M.; Teixeira, T. C. Bibcode: 2006ESASP1306..363M Altcode: 2006astro.ph..5685M We present the work undertaken by the Evolution and Seismic Tools Activity (ESTA) team of the CoRoT Seismology Working Group. We have focused on two main tasks: Task 1 now finished has aimed at testing, comparing and optimising seven stellar evolution codes which will be used to model the internal structure and evolution of the CoRoT target stars. Task 2, still underway, aims at testing, comparing and optimising different seismic codes used to calculate the oscillations of models for different types of stars. The results already obtained are quite satisfactory, showing minor differences between the different numerical tools provided the same assumptions on the physical parameters are made. This work gives us confidence on the numerical tools that will be available to interpret the future CoRoT seismic data. Title: The Seismology Programme of CoRoT Authors: Michel, E.; Baglin, A.; Auvergne, M.; Catala, C.; Aerts, C.; Alecian, G.; Amado, P.; Appourchaux, T.; Ausseloos, M.; Ballot, J.; Barban, C.; Baudin, F.; Berthomieu, G.; Boumier, P.; Bohm, T.; Briquet, M.; Charpinet, S.; Cunha, M. S.; De 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 de Medeiros, J.; De 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. Bibcode: 2006ESASP1306...39M Altcode: 2008arXiv0811.1080M 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. Title: Seismic Determination of Stellar Parameters Authors: Provost, J.; Berthomieu, G.; Gonczi, G.; Morel, P.; Toutain, T.; Barban, C.; Goupil, M. -J.; Lebreton, Y.; Michel, E.; Roxburgh, I. Bibcode: 2006ESASP1306..443P Altcode: In the context of the preparation for CoRoT, we have studied some theoretical properties of the frequencies of solar-like stars. In order to prepare for the interpretation of future data, we have defined between Meudon (LESIA) and Nice (Cassini) an hare and hounds exercise as follows: from a set of frequencies provided by each group and given to the other group, find the characteristics of the corresponding stellar model. Here are reported preliminary results obtained by the Nice group. A discussion on the numerical accuracy of theoretical frequencies is also given. Title: The DynaMICS perspective Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.624E..24T Altcode: 2006soho...18E..24T No abstract at ADS Title: How does the change on solar abundances affect low degree modes? Authors: Zaatri, A.; Provost, J.; Berthomieu, G.; Morel, P.; Corbard, T. Bibcode: 2006ESASP.624E..92Z Altcode: 2006soho...18E..92Z No abstract at ADS Title: Detection of periodic signatures in the solar power spectrum On the track of l=1 gravity modes Authors: García, R. A.; Turck-Chièze, S.; Jiménez-Reyes, S. J.; Ballot, J.; Pallé, P. L.; Eff-Darwich, A.; Mathur, S.; Provost, J. Bibcode: 2006ESASP.624E..23G Altcode: 2006astro.ph.11806G; 2006soho...18E..23G In the present work we show robust indications of the existence of g modes in the Sun using 10 years of GOLF data. The present analysis is based on the exploitation of the collective properties of the predicted low-frequency (25 to 140 microHz) g modes: their asymptotic nature, which implies a quasi equidistant separation of their periods for a given angular degree (l). The Power Spectrum (PS) of the Power Spectrum Density (PSD), reveals a significant structure indicating the presence of features (peaks) in the PSD with near equidistant periods corresponding to l=1 modes in the range n=-4 to n=-26. The study of its statistical significance of this feature was fully undertaken and complemented with Monte Carlo simulations. This structure has a confidence level better than 99.86% not to be due to pure noise. Furthermore, a detailed study of this structure suggests that the gravity modes have a much more complex structure than the one initially expected (line-widths, magnetic splittings...). Compared to the latest solar models, the obtained results tend to favor a solar core rotating significantly faster than the rest of the radiative zone. In the framework of the Phoebus group, we have also applied the same methodology to other helioseismology instruments on board SoHO and ground based networks. Title: The internal structure of the Sun inferred from g modes and low-frequency p modes Authors: Elsworth, Y. P.; Baudin, F.; Chaplin, W; Andersen, B; Appourchaux, T.; Boumier, P.; Broomhall, A. -M.; Corbard, T.; Finsterle, W.; Fröhlich, C.; Gabriel, A.; García, R. A.; Gough, D. O.; Grec, G.; Jiménez, A.; Kosovichev, A.; Provost, J.; Sekii, T.; Toutain, T.; Turck-Chièze, S. Bibcode: 2006ESASP.624E..22E Altcode: 2006soho...18E..22E The Phoebus group is an international collaboration of helioseismologists, its aim being to detect low-frequency solar g modes. Here, we report on recent work, including the development and application of new techniques based on the detection of coincidences in contemporaneous datasets and the asymptotic properties of the g-mode frequencies. The length of the time series available to the community is now more than ten years, and this has reduced significantly the upper detection limits on the g-mode amplitudes. Furthermore, low-degree p modes can now be detected clearly at frequencies below 1000 μHz. Title: Knowledge of the solar core dynamics through g modes Authors: Garcia, R. A.; Turck-Chièze, S.; Jimenez-Reyes, S. J.; Ballot, J.; Pallé, P. L.; Eff-Darwich, A.; Mathur, S.; Provost, J. Bibcode: 2006IAUJD..17E...8G Altcode: Helioseismology is able to study the solar interior through the observation of the solar oscillation modes propagating inside the Sun. Pressure-driven modes (p modes) provide a very detailed picture of the external convective zone above 0.7 R[⊙]and the radiative zone down to ~0.2 R[⊙] where only a few of such modes penetrate so far. To study deeper layers, still containing more than 40% of the totals mass, another type of oscillations are needed: the gravity-driven modes (g modes). Since the early 19 80s, this type of mode has been looked for. Only very recently have we have found some structures that are compatible with some global properties of these modes in the GOLF/ SOHO data. In this contribution we will show these signals. By explaining them as the signature of the asymptotic properties of the ℓ = 1 g modes, we could start constraining the solar core dynamics. Title: Scientific Objectives of the Novel Formation Flying Mission Aspiics Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.164L Altcode: 2006soho...17E.164L No abstract at ADS Title: The EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Science Plan and Instrument Overview Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.165W Altcode: 2006soho...17E.165W No abstract at ADS Title: Detection of the Periodic Signatures of l=1 Solar g Modes with 10 Years of GOLF/SOHO Data Authors: Garcia, Rafael A.; Turck-Chiéze, Sylvaine; Jiménez-Reyes, Sebastián J.; Ballot, Jerome; Palle, Pere L.; Eff-Darwich, Antonio; Mathur, Savita; Provost, Janine Bibcode: 2006ESASP.617E...3G Altcode: 2006soho...17E...3G No abstract at ADS Title: Recent Progresses on g-Mode Search Authors: Appourchaux, T.; Andersen, B.; Baudin, F.; Boumier, P.; Broomhall, A. -M.; Chaplin, W.; Corbard, T.; Elsworth, Y.; Finsterle, W.; Fröhlich, C.; Gabriel, A.; Garcia, R.; Gough, D. O.; Grec, G.; Jiménez, A.; Kosovichev, A.; Provost, J.; Sekii, T.; Toutain, T.; Turck-Chièze, S. Bibcode: 2006ESASP.617E...2A Altcode: 2006soho...17E...2A No abstract at ADS Title: The Dynamics Project Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.162T Altcode: 2006soho...17E.162T No abstract at ADS Title: About Procyon modeling Authors: Provost, J.; Berthomieu, G.; Martić, M. Bibcode: 2006MmSAI..77..474P Altcode: Models of Procyon satisfying the actual observational constraints, particularly the asteroseismic ones, are discussed. It is shown that much more accurate frequencies must be obtained by asteroseismic observations especially in the low frequency domain below 800 mu Hertz to determine the Procyon evolutionary stage. Title: Effect of microscopic diffusion on asteroseismic properties of intermediate-mass stars Authors: Provost, J.; Berthomieu, G.; Bigot, L.; Morel, P. Bibcode: 2005A&A...432..225P Altcode: Results on the effects of microscopic diffusion on the modeling and oscillations of

solar-like stars are discussed. Comparisons between models with and without microscopic diffusion, subjected to observational constraints, namely effective temperature, luminosity, surface metallicity and mass

derived from photometry, spectroscopy and astrometry, are presented. We point out and discuss a signature of microscopic diffusion on the oscillation frequencies. Title: JISCO: Jovian Interferometric Seismometer at Concordia Observatory Authors: Schmider, F. X.; Jacob, C.; Fossat, E.; Abe, L.; Gay, J.; Valtier, J. -C.; Guillot, T.; Provost, J.; Mosser, B.; Gaulme, P. Bibcode: 2005EAS....14..285S Altcode: Seismology is the only way to investigate the internal structure of the giant planets, with a lot of scientific implications such as high pressure physics and huge constraints on the scenario of solar system formation. As compared to other existing possibilities (ground based network, spacecraft), seismology of Jupiter will take a maximum benefit from the peculiarities of the Concordia station as an astronomical observatory. Indeed, the continuous temporal coverage for all the winter season, and the quality of the atmospheric seeing, are crucial parameters for this program. The jovian seismometer SYMPA, already used for network observations, is perfectly suitable for Dome C conditions. With the already existing small telescopes deployed in the frame of site testing program, seismology of Jupiter will constitute a excellent intermediate project with high scientific return, before the installation of large telescopes. In a second step, such an instrument could be a first light instrument for a 1.5 m class automatic telescope, which is to be developed as an individual stone for a large interferometer. With this diameter, the same scientific program on Saturn could also be achieved. Title: About Models and Oscillations of the Solar-Like Star Procyon a Authors: Provost, J.; Martic, M.; Berthomieu, G. Bibcode: 2004ESASP.559..594P Altcode: 2004soho...14..594P No abstract at ADS Title: GOLF : Probing the Observed Low Frequency Spectrum with a Numerical Model Authors: Grec, G.; Provost, J.; Renaud, C.; Berthomieu, G. Bibcode: 2004ESASP.559..452G Altcode: 2004soho...14..452G No abstract at ADS Title: New values of gravitational moments J2 and J4 deduced from helioseismology Authors: Mecheri, R.; Abdelatif, T.; Irbah, A.; Provost, J.; Berthomieu, G. Bibcode: 2004SoPh..222..191M Altcode: 2009arXiv0911.5055R By applying the theory of slowly rotating stars to the Sun, the solar quadrupole and octopole moments J2 and J4 were computed using a solar model obtained from CESAM stellar evolution code (Morel, 1997) combined with a recent model of solar differential rotation deduced from helioseismology (Corbard et al., 2002). This model takes into account a near-surface radial gradient of rotation which was inferred and quantified from MDI f-mode observations by Corbard and Thompson (2002). The effect of this observational near-surface gradient on the theoretical values of the surface parameters J2, J4 is investigated. The results show that the octopole moment J4 is much more sensitive than the quadrupole moment J2 to the subsurface radial gradient of rotation. Title: Erratum: ``Looking for Gravity-Mode Multiplets with the GOLF Experiment aboard SOHO'' (ApJ, 604, 455 [2004]) Authors: Turck-Chièze, S.; García, R. A.; Couvidat, S.; Ulrich, R. K.; Bertello, L.; Varadi, F.; Kosovichev, A. G.; Gabriel, A. H.; Berthomieu, G.; Brun, A. S.; Lopes, I.; Pallé, P.; Provost, J.; Robillot, J. M.; Roca Cortés, T. Bibcode: 2004ApJ...608..610T Altcode: As a result of an error at the Press, the second panel of Figure 9 was repeated twice in the top row of the printed, black-and-white version of this figure, and the first panel was omitted. This error appears in the print edition and the PDF and postscript (PS) versions available with the electronic edition of the journal, although the panels of the color figure displayed in the electronic article itself are correct. Please see below for the corrected print version of Figure 9. The Press sincerely regrets the error. Title: Looking for Gravity-Mode Multiplets with the GOLF Experiment aboard SOHO Authors: Turck-Chièze, S.; García, R. A.; Couvidat, S.; Ulrich, R. K.; Bertello, L.; Varadi, F.; Kosovichev, A. G.; Gabriel, A. H.; Berthomieu, G.; Brun, A. S.; Lopes, I.; Pallé, P.; Provost, J.; Robillot, J. M.; Roca Cortés, T. Bibcode: 2004ApJ...604..455T Altcode: This paper is focused on the search for low-amplitude solar gravity modes between 150 and 400 μHz, corresponding to low-degree, low-order modes. It presents results based on an original strategy that looks for multiplets instead of single peaks, taking into consideration our knowledge of the solar interior from acoustic modes. Five years of quasi-continuous measurements collected with the helioseismic GOLF experiment aboard the SOHO spacecraft are analyzed. We use different power spectrum estimators and calculate confidence levels for the most significant peaks. This approach allows us to look for signals with velocities down to 2 mm s-1, not far from the limit of existing instruments aboard SOHO, amplitudes that have never been investigated up to now. We apply the method to series of 1290 days, beginning in 1996 April, near the solar cycle minimum. An automatic detection algorithm lists those peaks and multiplets that have a probability of more than 90% of not being pure noise. The detected patterns are then followed in time, considering also series of 1768 and 2034 days, partly covering the solar cycle maximum. In the analyzed frequency range, the probability of detection of the multiplets does not increase with time as for very long lifetime modes. This is partly due to the observational conditions after 1998 October and the degradation of these observational conditions near the solar maximum, since these modes have a ``mixed'' character and probably behave as acoustic modes. Several structures retain our attention because of the presence of persistent peaks along the whole time span. These features may support the idea of an increase of the rotation in the inner core. There are good arguments for thinking that complementary observations up to the solar activity minimum in 2007 will be decisive for drawing conclusions on the presence or absence of gravity modes detected aboard the SOHO satellite. Title: The diameter and evolutionary state of Procyon A. Multi-technique modeling using asteroseismic and interferometric constraints Authors: Kervella, P.; Thévenin, F.; Morel, P.; Berthomieu, G.; Bordé, P.; Provost, J. Bibcode: 2004A&A...413..251K Altcode: 2003astro.ph..9148K We report the angular diameter measurement obtained with the VINCI/VLTI instrument on the nearby star Procyon A (α CMi A, F5IV-V), at a relative precision of ± 0.9%. We obtain a uniform disk angular diameter in the K band of θUD = 5.376±0.047 mas and a limb darkened value of θLD = 5.448±0.053 mas. Together with the HIPPARCOS parallax, this gives a linear diameter of 2.048±0.025 D⊙. We use this result in combination with spectroscopic, photometric and asteroseismic constraints to model this star with the CESAM code. One set of modeling parameters that reproduces the observations within their error bars are an age of 2314 Myr, an initial helium mass fraction Y_i=0.301 and an initial mass ratio of heavy elements to hydrogen (Z/X)i=0.0314. We also computed the adiabatic oscillation spectrum of our model of Procyon A, giving a mean large frequency separation of /line{Δν0}≈ 54.7 μHz. This value is in agreement with the seismic observations by Martić et al. (\cite{martic}, \cite{martic01}). The interferometric diameter and the asteroseismic large frequency spacing together suggest a mass closer to 1.4 M⊙ than to 1.5 M⊙. We conclude that Procyon is currently ending its life on the main sequence, as its luminosity class indicates. Title: VINCI/VLTI Observations of Main Sequence Stars Authors: Kervella, P.; Thévenin, F.; Morel, P.; Provost, J.; Berthomieu, G.; Sé Gransan, D.; Queloz, D.; Bordé, P.; di Folco, E.; Forveille, T. Bibcode: 2004IAUS..219...80K Altcode: 2003astro.ph..9784K; 2003IAUS..219E.127K The Main Sequence (MS) stars are by far the most numerous class in the Universe. They are often somewhat neglected as they are relatively quiet objects (but exceptions exist) though they bear testimony of the past and future of our Sun. An important characteristic of the MS stars particularly the solar-type ones is that they host the large majority of the known extrasolar planets. Moreover at the bottom of the MS the red M dwarfs pave the way to understanding the physics of brown dwarfs and giant planets themselves. We have measured very precise angular diameters from recent VINCI/VLTI observations of a number of MS stars with spectral types between A1 and M5.5 which already cover a wide range of effective temperatures and radii. Combined with precise Hipparcos parallaxes photometry spectroscopy as well as the asteroseismic information available for some of these stars the angular diameters put strong constraints on the detailed models of these stars and therefore on the physical processes at play. Title: The diameters of alpha Centauri A and B. A comparison of the asteroseismic and VINCI/VLTI views Authors: Kervella, P.; Thévenin, F.; Ségransan, D.; Berthomieu, G.; Lopez, B.; Morel, P.; Provost, J. Bibcode: 2003A&A...404.1087K Altcode: 2003astro.ph..3634K We compare the first direct angular diameter measurements obtained on our closest stellar neighbour, alpha Centauri, to recent model diameters constrained by asteroseismic observations. Using the VINCI instrument installed at ESO's VLT Interferometer (VLTI), the angular diameters of the two main components of the system, alpha Cen A and B, were measured with a relative precision of 0.2% and 0.6% respectively. Particular care has been taken in the calibration of these measurements, considering that VINCI is estimating the fringe visibility using a broadband K filter. We obtain uniform disk angular diameters for alpha Cen A and B of thetaUD [A] = 8.314 +/- 0.016 mas and thetaUD [B] = 5.856 +/- 0.027 mas, and limb darkened angular diameters of thetaLD [A] = 8.511 +/- 0.020 mas and thetaLD [B] = 6.001 +/- 0.034 mas. Combining these values with the parallax from Söderhjelm (\cite{soderhjelm}), we derive linear diameters of D[A] = 1.224 +/- 0.003 Dsun and D[B] = 0.863 +/- 0.005 Dsun. These values are compatible with the masses published by Thévenin et al. (\cite{thevenin02}) for both stars. Title: Solar oblateness induced by its differential rotation Authors: Mecheri, R.; Provost, J.; Abdelatif, T.; Irbah, A. Bibcode: 2003EAEJA....14676M Altcode: By using the theory of Solar gravitational figure, the solar quadrupole moment J2 was computed combined with a recent analytical model of differential solar rotation (Corbard et al. 2002) taking into account a near-surface radial gradient of rotation inferred and quantified from MDI f-modes observations. This value of J2 obtained permits to evaluate the solar oblateness and its induced latitudinal variation of solar diameter. This variation was compared to those obtained from observations. Title: Asteroseismology of alpha Centauri from Concordia Authors: Grec, G.; Renaud, C.; Berthomieu, G.; Provost, J. Bibcode: 2003MSAIS...2..162G Altcode: Following the significative progress in the knowledge of the solar interior due to the analysis of the acoustical eigen modes, the observationnal chalenge is presently to obtain similar data for several other solar-like dwarf stars, leading to a new determination of their fundamental data as mass and age. On a southern site, the bright binary star alpha Centauri is the higher priority. Our group works on the concept and realisation of an automated photometer usable for long observations covering the antarctic night. An evolution to the measurement of the variations of radial velocity of bright stars is also considered. Title: New Determination of Solar Gravitational Moments j2 and J4. Authors: Mecheri, Redouane; Provost, Janine; Abdelatif, Toufik E.; Irbah, Abdenour Bibcode: 2003IAUJD..12E..11M Altcode: By using the theory of Solar gravitational figure the solar quadrupole and octopole moment respectively J2 and J4 were computed using Nice Observatory solar model (P.Morel et al. (1997)) combined with a new analytical model of solar differential rotation (Corbard et al. 2002) taking into account a near-surface radial gradient of rotation inferred and quantified from MDI f-modes observations. The values of J2 and J4 obtained permit to evaluate the solar oblateness and it's induced latitudinal variations of solar diameter in order to compare them to those obtained from observations. We also use J2 to calculate its contribution to the advance of the perihelion of Mercury for which the found value is in agreement with the theory of General Relativity and the measurements of Mercury's orbit by means of planetary ranging radar. Title: Revisited Calibration of Cen Binary System Authors: Provost, J.; Berthomieu, G.; Thévenin, F.; Morel, P.; Bouchy, F.; Carrier, F. Bibcode: 2003aahd.conf..557P Altcode: No abstract at ADS Title: SYMPA: A Dedicated Instrument and a Network for Seismology of Giant Planets Authors: Schmider, F. -X.; Gay, J.; Jacob, C.; Fossat, E.; Valtier, J. -C.; Mosser, B.; Mekarnia, D.; Guillot, T.; Provost, J. Bibcode: 2003aahd.conf..449S Altcode: No abstract at ADS Title: Asteroseismology and calibration of alpha Cen binary system Authors: Thévenin, F.; Provost, J.; Morel, P.; Berthomieu, G.; Bouchy, F.; Carrier, F. Bibcode: 2002A&A...392L...9T Altcode: 2002astro.ph..6283T Using the oscillation frequencies of alpha Cen A recently discovered by Bouchy & Carrier (\cite{bc01}, \cite{bc02}), the available astrometric, photometric and spectroscopic data, we tried to improve the calibration of the visual binary system alpha Cen. With the revisited masses of Pourbaix et al. (\cite{pnm02}) we did not succeed in obtaining a solution satisfying all the seismic observational constraints. Relaxing the constraints on the masses, we have found an age talpha Cen=4850+/-500 Myr, an initial helium mass fraction Yi = 0.300+/-0.008, and an initial metallicity (Z/X)i=0.0459+/-0.0019, with MA=1.100+/-0.006 Msun and MB= 0.907+/-0.006 Msun for alpha Cen A & B. Title: A search for solar g modes in the GOLF data Authors: Gabriel, A. H.; Baudin, F.; Boumier, P.; García, R. A.; Turck-Chièze, S.; Appourchaux, T.; Bertello, L.; Berthomieu, G.; Charra, J.; Gough, D. O.; Pallé, P. L.; Provost, J.; Renaud, C.; Robillot, J. -M.; Roca Cortés, T.; Thiery, S.; Ulrich, R. K. Bibcode: 2002A&A...390.1119G Altcode: With over 5 years of GOLF data having some 90% continuity, a new attempt has been made to search for possible solar g modes. Statistical methods are used, based on the minimum of assumptions regarding the solar physics; namely that mode line-widths are small compared with the inverse of the observing time, and that modes are sought in the frequency interval 150 to 400 mu Hz. A number of simulations are carried out in order to understand the expected behaviour of a system consisting principally of a solar noise continuum overlaid with some weak sharp resonances. The method adopted is based on the FFT analysis of a time series with zero-padding by a factor of 5. One prominent resonance at 284.666 mu Hz coincides with a previous tentative assignment as one member of an n=1, l=1, p-mode multiplet. Components of two multiplets, previously tentatively identified as possible g-mode candidates from the GOLF data in 1998, continue to be found, although their statistical significance is shown to be insufficient, within the present assumption regarding the nature of the signal. An upper limit to the amplitude of any g mode present is calculated using two different statistical approaches, according to either the assumed absence (H0 hypothesis) or the assumed presence (H1 hypothesis) of a signal. The former yields a slightly lower limit of around 6 mm/s. Title: Global low frequency acoustic modes after half a solar cycle aboard SOHO: an improved view of the nuclear core Authors: Turck-Chièze, S.; Garcí, R. A.; Couvidat, S.; Kosovichev, A. G.; Bertello, L.; Corbad, T.; Berthomieu, G.; Provost, J.; Eff-Darwich, A. Bibcode: 2002ESASP.508..593T Altcode: 2002soho...11..593T Solar global oscillations have now been measured for more than 20 years. The study of these modes has contributed to improve, along time, the description of the solar core. We have now a proper access to this part of the Sun, with ground networks observing for more than 10 years and the three instruments aboard SOHO in a quasi continuous mode for now half a cycle. In this talk, we show the advantages of the global acoustic modes measured at low frequency. They are due to their longer lifetime and the reduced influence of the turbulent and variable surface effects. As a consequence, we have converged last year, after 30 years of unsuccess, to a boron-8 emitted neutrino flux in perfect agreement with the better understood detection of these neutrinos on earth. The splitting at low frequency is also now properly determined but the extracted rotation information is still limited in the core. It contains nevertheless the first dynamical vision of this part of the radiative zone. We will focus on it up to the end of the SOHO mission, together with the gravity mode region and the possible internal signature of the magnetic field. Some limits are given on these observables. Further improvements of their detectability are under study and will be mentioned. Title: SYMPA: A Specified Instrument and a Dedicated Network for Giant Planets' Sismology Authors: Schmider, F. X.; Gay, Jean; Jacob, Cedric; Fossat, Eric; Valtier, Jean-Claude; Mossier, Benoît; Mekarnia, Djamel; Guillot, Tristan; Provost, Janine Bibcode: 2002sf2a.conf..611S Altcode: The poster I will propose is about the 'SYMPA' project, an instrument dedicated to the study of giant planets interiors, in paricular Jupiter, based on principles of asterosismology. This instrument, developped in collaboration between the department Fresnel of the Observatoire de la Cote d'Azur, and the Laboratoire d'Astrophysique of Nice University, is a Mach-Zender interferometer allowing observations of radial velocities on jovien surface. The poster presents the contribution of sismology to knowledge of planetary interiors, the principle of this new imaging instrument and its performances, and some results from first observations in february and march 2002. Title: Constraints derived from binary systems calibration: some examples Authors: Berthomieu, G.; Morel, P.; Provost, J.; Thevenin, F. Bibcode: 2002ASPC..274..199B Altcode: 2002ohds.conf..199B No abstract at ADS Title: On the properties of solar-like oscillations: application to Procyon Authors: Provost, J.; Martić, M.; Berthomieu, G.; Morel, P. Bibcode: 2002ESASP.485..309P Altcode: 2002sshp.conf..309P In order to interpret the ground-based observations of solar-like stellar oscillations and prepare the scientific exploitation of future spatial asteroseismic observations, we have studied the theoretical properties of the frequencies of possible models for a given stellar target, taking into account its observational constraints in the Hertzsprung-Russell diagram. We have computed a set of "calibrated" stellar models satisfying these constraints for a star of solar metallicity. We present some results on the sensitivity of the oscillation frequencies to the description of the convective transport and to physical processes entering in the stellar modeling, like core overshoot. We compare the seismic properties of our models with the observations of Procyon by Martić et al. (2001). Title: P-Mode Observations on α Cen A with CORALIE Authors: Carrier, F.; Bouchy, F.; Meynet, G.; Maeder, A.; Provost, J.; Berthomieu, G.; Morel, P.; Thévenin, F. Bibcode: 2002ASPC..259..460C Altcode: 2002rnpp.conf..460C; 2002IAUCo.185..460C No abstract at ADS Title: The zeta Herculis binary system revisited. Calibration and seismology Authors: Morel, P.; Berthomieu, G.; Provost, J.; Thévenin, F. Bibcode: 2001A&A...379..245M Altcode: 2001astro.ph.10004M We have revisited the calibration of the visual binary system zeta Herculis with the goal to give the seismological properties of the G0 IV sub-giant zeta Her A. The sum of masses and the mass fraction are derived from the most recent astrometric data mostly based on the HIPPARCOS ones. We have derived the effective temperatures, the luminosities and the metallicities from available spectroscopic data and TYCHO photometric data and calibrations. For the calculations of evolutionary models we have used updated physics and the most recent physical data. A chi 2 minimization is performed to approach the most reliable modeling parameters which reproduce the observations within their error bars. For the age of the zeta Her binary system we have obtained tzeta Her=3387 Myr, for the masses mzeta Her A=1.45 Msun and mzeta Her B=0.98 Msun, for the initial helium mass fraction Yi=0.243, for the initial mass ratio of heavy elements to hydrogen (Z/X)i= 0.0269 and for the mixing-length parameters Lambda zeta Her A=0.92 and Lambda zeta Her B=0.90 using the Canuto & Mazitelli (\cite{cm91}, \cite{cm92}) convection theory. Our results do not exclude that zeta Her A is itself a binary sub-system as has been suspected many times in the past century; the mass of the hypothetical unseen companion would be mzeta Her Aloa 0.05 Msun, a value significantly smaller than previous determinations. A calibration made with an overshoot of the convective core of zeta Her A leads to similar results but with a slight increase of ~+250 Myr for the age. The adiabatic oscillation spectrum of zeta Her A is found to be a complicated superposition of acoustic and gravity modes. Some of these waves have a dual character. This greatly complicates the classification of the non-radial modes. For l=1 the modes all have both energy in the core and in the envelope; they are mixed modes. For l=2,3 there is a succession of modes with energy either in the core or in the envelope with a few mixed modes. The echelle diagram used by the observers to extract the frequencies will work for l=0, 2, 3. The large difference is found to be of the order of /line{Delta nu0 }~ 42 mu Hz, in agreement with the Martić et al. (\cite{mlsab01}) seismic observations. Title: Solar Neutrino Emission Deduced from a Seismic Model Authors: Turck-Chièze, S.; Couvidat, S.; Kosovichev, A. G.; Gabriel, A. H.; Berthomieu, G.; Brun, A. S.; Christensen-Dalsgaard, J.; García, R. A.; Gough, D. O.; Provost, J.; Roca-Cortes, T.; Roxburgh, I. W.; Ulrich, R. K. Bibcode: 2001ApJ...555L..69T Altcode: Three helioseismic instruments on the Solar and Heliospheric Observatory have observed the Sun almost continuously since early 1996. This has led to detailed study of the biases induced by the instruments that measure intensity or Doppler velocity variation. Photospheric turbulence hardly influences the tiny signature of conditions in the energy-generating core in the low-order modes, which are therefore very informative. We use sound-speed and density profiles inferred from GOLF and MDI data including these modes, together with recent improvements to stellar model computations, to build a spherically symmetric seismically adjusted model in agreement with the observations. The model is in hydrostatic and thermal balance and produces the present observed luminosity. In constructing the model, we adopt the best physics available, although we adjust some fundamental ingredients, well within the commonly estimated errors, such as the p-p reaction rate (+1%) and the heavy-element abundance (+3.5%); we also examine the sensitivity of the density profile to the nuclear reaction rates. Then, we deduce the corresponding emitted neutrino fluxes and consequently demonstrate that it is unlikely that the deficit of the neutrino fluxes measured on Earth can be explained by a spherically symmetric classical model without neutrino flavor transitions. Finally, we discuss the limitations of our results and future developments. Title: PICARD: solar diameter measure and g-mode search Authors: Damé, L.; Appourchaux, T.; Berthomieu, G.; Boumier, P.; Cugnet, D.; Gelly, B.; Provost, J.; Toutain, T. Bibcode: 2001ESASP.464..321D Altcode: 2001soho...10..321D The PICARD microsatellite mission will provide 3 to 4 years simultaneous measurements of the solar diameter, differential rotation and solar constant to investigate the nature of their relations and variabilities. The major instrument, SODISM, is a whole Sun imaging telescope of Ø 110 mm which will deliver an absolute measure (better than 4 mas) of the solar diameter and solar shape. Now in Phase B, PICARD is expected to be launched by 2005. We recall the scientific goals linked to the diameter measurement with emphasis on the helioseismology g-mode interest, present the instrument optical concept and present design, and give a brief overview of the program aspects. Title: α Centauri binary system: calibration and oscillations Authors: Provost, J.; Berthomieu, G.; Morel, P.; Lebreton, Y.; Thévenin, F. Bibcode: 2001ESASP.464..439P Altcode: 2001soho...10..439P The two members of the visual binary α Centauri A & B provide a great potentiality of testing stellar physics in conditions slightly different from the solar ones and then deserve undivided attention for internal structure modeling and oscillation frequencies calculations. Detailed evolutionary models, including pre main-sequence evolution have been performed using the recently determined masses of Pourbaix et al. (1999). Models have been constructed with updated physics including microscopic diffusion, different convection theories and possible convective core overshoot. A χ2 minimization is empolyed to derive the age of the system, the initial helium content, the initial mass ratio of heavy elements to hydrogen and the convection parameters of each star model. A seismological analysis of our calibrated models has been performed. Title: About structure inversions of simulated COROT data for a solar like star Authors: Berthomieu, G.; Toutain, T.; Gonczi, G.; Corbard, T.; Provost, J.; Morel, P. Bibcode: 2001ESASP.464..411B Altcode: 2001soho...10..411B We study the potential of exploring the internal structure of solar like stars which could be observed by COROT. We consider a solar like star of mass and age which allows stochastically excited oscillations according to the results of Houdek et al (1999). Taking into account COROT observational constraints we estimate a set of observable modes with the uncertainties on their frequencies; then, in the same way followed by Gough and Kosovichev (1993), we evaluate the possibility of inferring structure properties of the star using inversion techniques. Title: g-mode detection: Where do we stand? Authors: Appourchaux, T.; Andersen, B.; Berthomieu, G.; Chaplin, W.; Elsworth, Y.; Finsterle, W.; Frölich, C.; Gough, D. O.; Hoeksema, T.; Isaak, G.; Kosovichev, A.; Provost, J.; Scherrer, P.; Sekii, T.; Toutain, T. Bibcode: 2001ESASP.464..467A Altcode: 2001soho...10..467A We review the recent developments in determining the upper limits to g-mode amplitudes obtained by SOHO instruments, GONG and BiSON. We address how this limit can be improved by way of new helioseismic instruments and/or new collaborations, hopefully providing in the not too distant future unambiguous g-mode detection. Title: Calibrations of alpha Centauri A & B Authors: Morel, P.; Provost, J.; Lebreton, Y.; Thévenin, F.; Berthomieu, G. Bibcode: 2000A&A...363..675M Altcode: 2000astro.ph.10180M Detailed evolutionary models of the visual binary alpha Centauri, including pre main-sequence evolution, have been performed using the masses recently determined by Pourbaix et al. (\cite{pnn99}). Models have been constructed using the CEFF equation of state, OPAL opacities, NACRE thermonuclear reaction rates and microscopic diffusion. A chi 2-minimization is performed to derive the most reliable set of modeling parameters wp = {talpha Cen,Yi,[frac {FeH]i},alphaA ,alphaB }, where talpha Cen is the age of the system, Yi the initial helium content, [frac {FeH]i} the initial metallicity and, alphaA and alphaB the convection parameters of the two components. Using the basic Böhm-Vitense (\cite{b58}) mixing-length theory of convection, we derive wpBV =2710 Myr, 0.284,0.257,1.53,1.57. We obtain a noticeably smaller age than estimated previously, in agreement with Pourbaix et al. (\cite{pnn99}), mainly because of the larger masses. If convective core overshoot is considered we get wpov =3530 Myr, 0.279,0.264,1.64,1.66\. The use of Canuto & Mazitelli (\cite{cm91,cm92}) convection theory leads to the set wpCM =4086 Myr, 0.271,0.264,0.964,0.986\. Using the observational constraints adopted by Guenther & Demarque (\cite{gd00}), and the basic mixing-length theory, we obtain wpGD =5640 Myr, 0.300,0.296,1.86,1.97 and surface lithium depletions close to their observed values. A seismological analysis of our calibrated models has been performed. The determination of large and small spacings between the frequencies of acoustic oscillations from seismic observations would help to discriminate between the models of alpha Cen computed with different masses and to confirm or rule out the new determination of masses. Title: Observational Upper Limits to Low-Degree Solar g-Modes Authors: Appourchaux, T.; Fröhlich, C.; Andersen, B.; Berthomieu, G.; Chaplin, W. J.; Elsworth, Y.; Finsterle, W.; Gough, D. O.; Hoeksema, J. T.; Isaak, G. R.; Kosovichev, A. G.; Provost, J.; Scherrer, P. H.; Sekii, T.; Toutain, T. Bibcode: 2000ApJ...538..401A Altcode: Observations made by the Michelson Doppler Imager (MDI) and Variability of solar IRradiance and Gravity Oscillations (VIRGO) on the Solar and Heliospheric Observatory (SOHO) and by the ground-based Birmingham Solar Oscillations Network (BiSON) and Global Oscillations Network Group (GONG) have been used in a concerted effort to search for solar gravity oscillations. All spectra are dominated by solar noise in the frequency region from 100 to 1000 μHz, where g-modes are expected to be found. Several methods have been used in an effort to extract any g-mode signal present. These include (1) the correlation of data-both full-disk and imaged (with different spatial-mask properties)-collected over different time intervals from the same instrument, (2) the correlation of near-contemporaneous data from different instruments, and (3) the extraction-through the application of complex filtering techniques-of the coherent part of data collected at different heights in the solar atmosphere. The detection limit is set by the loss of coherence caused by the temporal evolution and the motion (e.g., rotation) of superficial structures. Although we cannot identify any g-mode signature, we have nevertheless set a firm upper limit to the amplitudes of the modes: at 200 μHz, they are below 10 mm s-1 in velocity, and below 0.5 parts per million in intensity. The velocity limit corresponds very approximately to a peak-to-peak vertical displacement of δR/Rsolar=2.3×10-8 at the solar surface. These levels which are much lower than prior claims, are consistent with theoretical predictions. Title: Structure of the Solar Core: Effect of Asymmetry of Peak Profiles Authors: Basu, S.; Turck-Chièze, S.; Berthomieu, G.; Brun, A. S.; Corbard, T.; Gonczi, G.; Christensen-Dalsgaard, J.; Provost, J.; Thiery, S.; Gabriel, A. H.; Boumier, P. Bibcode: 2000ApJ...535.1078B Altcode: 2000astro.ph..1208B Recent studies have established that peaks in solar oscillation power spectra are not Lorentzian in shape but have a distinct asymmetry. Fitting a symmetric Lorentzian profile to the peaks, therefore, produces a shift in frequency of the modes. Accurate determination of low-frequency modes is essential to infer the structure of the solar core by inversion of the mode frequencies. In this paper we investigate how the changes in frequencies of low-degree modes obtained by fitting symmetric and asymmetric peak profiles change the inferred properties of the solar core. We use data obtained by the Global Oscillations at Low Frequencies (GOLF) project on board the SOHO spacecraft. Two different solar models and inversion procedures are used to invert the data in order to determine the sound speed in the solar core. We find that for a given set of modes no significant difference in the inferred sound speed results from taking asymmetry into account when fitting the low-degree modes. Title: Non-axisymmetric oscillations of roAp stars Authors: Bigot, L.; Provost, J.; Berthomieu, G.; Dziembowski, W. A.; Goode, P. R. Bibcode: 2000A&A...356..218B Altcode: We calculate the effect of a strong dipole magnetic field on non-axisymmetric oscillations for roAp stars, with a typical range of photospheric magnetic fields B_p [0.5-1.5] kG. As Dziembowski & Goode (1996), we find that the oscillations are strongly affected by such magnetic fields in two different ways. The first one concerns the stability of modes, which are damped due to dissipation by Alfvénic waves. It leads to a small imaginary part of the frequency, about (1-15mu Hz). The real part of the frequencies is also affected and is greater in the presence of magnetic field, with a shift of about 1-20 mu Hz. We find that these shifts are strongly influenced by the geometry of the mode, i.e. the value of the degree l, as it has already been shown by Dziembowski & Goode (1996), and also by m, the azimuthal degree, with a significant amplitude. The magnetic field, because it breaks the spherical symmetry of the problem, raises partially the (2 l +1) degeneracy of frequency in m. We find that the shift of both the real and imaginary parts is always greater than in the case of axisymmetric oscillations (m=0), except for sectoral modes (l=m), for which the imaginary part is smaller. The second effect of large magnetic fields is to complicate the mode identification. The perturbations cannot be represented by pure single spherical harmonic, but by a series of harmonics due to the angular dependence of the Lorentz force. It is shown that this mixing of spherical harmonics also depends on the value of m. However, our calculations do not explain the observed selection of dipole modes in roAp stars, aligned with the magnetic axis, since they do not minimize energy losses due to Alfvénic waves. Title: Calibration of iota Pegasi system Authors: Morel, P.; Morel, Ch.; Provost, J.; Berthomieu, G. Bibcode: 2000A&A...354..636M Altcode: 1999astro.ph.12307M Recent observations provide determinations of individual masses, chemical composition and metallicity of the components of the spectroscopic and interferometric binary iota Peg (Boden et al. \cite{bkb99}). Using updated physics, to calibrate the system, we have computed using the stellar evolutionary code CESAM (Morel \cite{m97}), evolutionary sequences of stellar models with the masses of iota Peg A 1.326 M_sun and iota Peg B 0.819 M_sun (Boden et al. loc. cit) and with different values of the mixing-length parameter alpha , the helium Y and the heavy element Z initial mass fraction with the constraint of the observed metallicity. Adopting effective temperatures and luminosities, as derived from observations with the bolometric corrections, and the empirical scale of temperatures of Alonso et al. (\cite{aam95}, \cite{aam96}), we find alpha_A =1.46, alpha_B =1.36, Y=0.278, Z=0.017. The evolution time, including pre-main sequence, is found within ~ 40 My<~ t_ev<~ 0.5 Gy. The calibrated models of iota Peg. A and B are non homogeneous zero age main sequence stars with the evolutionary time t_ev=56 My. Due to the large uncertainties of their determinations, the values derived for the mixing-length parameters are smaller than the solar one but however marginally compatible with it. Our results ought to be improved as soon as a more accurate value of the magnitude difference in the V filter will be available. Detailed spectroscopic analysis for both components looks practicable, so it is urgently needed. Title: Low-frequency p- and g-mode solar oscillations Authors: Provost, J.; Berthomieu, G.; Morel, P. Bibcode: 2000A&A...353..775P Altcode: In order to help the detection and identification of low-frequency p- and g-modes in the solar spectrum observed by ground-based networks and SoHO experiments, we study the properties of low degree (l=0 - 6) low-frequency (100 - 2000 mu Hz) solar oscillations. The frequencies of p- and g-modes have been computed for a set of solar models with updated physics. We point out the specific properties of the oscillations of mixed character, with noticeable amplitude both in central and external layers. We analyze the sensitivity of low-frequency oscillations to solar parameters like age, metallicity and luminosity, and to various physical processes, like convective core overshoot and mass loss during the beginning of solar evolution. We estimate the sensitivity of the splittings of these low-frequency oscillations to the core rotation. Title: About the time of evolution of a solar model Authors: Morel, P.; Provost, J.; Berthomieu, G. Bibcode: 2000A&A...353..771M Altcode: 1999astro.ph.10388M The evolution of a solar model is initialized with homogeneous models of either, pre-main sequence (P-models) or, zero-age main sequence (Z-models). The zero-age of a solar model is conventionally referenced as the time where the nuclear reactions just begin to dominate gravitation as the primary source of energy. Fixing the physics, we found that the structure of P- and Z-models computed with the same physics are almost similar soon after the exhaustion of their convective core. This similarity gives a connection between the age of the Sun t_sun and the time t_cal elapsed in the calculation of calibrated solar models. We found that a Z-model calibrated with t_cal=t_sun and a P-model calibrated with t_cal=t_sun+25 My, are indistinguishable at the relative accuracy level of a few 10-4. Title: Solar models and NACRE thermonuclear reaction rates Authors: Morel, P.; Pichon, B.; Provost, J.; Berthomieu, G. Bibcode: 1999A&A...350..275M Altcode: 1999astro.ph..7381M Using the most recent updated physics, calibrated solar models have been computed with the new thermonuclear reaction rates of NACRE, the recently available European compilation. Comparisons with models computed with the reaction rates of Caughlan & Fowler (\cite{cf88}) and of Adelberger et al. (\cite{a98}) are made for global structure, expected neutrinos fluxes, chemical composition and sound speed profiles, helioseismological properties of p-modes and g-modes. Title: Non linear regularization for helioseismic inversions. Application for the study of the solar tachocline Authors: Corbard, T.; Blanc-Féraud, L.; Berthomieu, G.; Provost, J. Bibcode: 1999A&A...344..696C Altcode: 1999astro.ph..1112C Inversions of rotational splittings have shown that there exists at the base of the solar convection zone a region called the tachocline in which high radial gradients of the rotation rate occur. The usual linear regularization methods tend to smooth out any high gradients in the solution, and may not be appropriate for the study of this zone. In this paper we use, in the helioseismic context of rotation inversions, regularization methods that have been developed for edge-preserving regularization in computed imaging. It is shown from Monte-Carlo simulations that this approach can lead directly to results similar to those reached by linear inversions which however required some assumptions on the shape of the transition in order to be deconvolved. The application of this method to LOWL data leads to a very thin tachocline. From the discussions on the parameters entering the inversion and the Monte-Carlo simulations, our conclusion is that the tachocline width is very likely below 0.05R_sun which lowers our previous estimate of 0.05+/- 0.03R_sun obtained from the same dataset (Corbard et al. 1998). Title: Light perturbation from stellar nonradial oscillations: an application to solar oscillations Authors: Toutain, T.; Berthomieu, G.; Provost, J. Bibcode: 1999A&A...344..188T Altcode: We derive analytical expressions for the emerging intensity and flux perturbations due to stellar nonradial oscillations taking into account the sphericity of the emitting layers. These expressions are derived using both the Eulerian and Lagrangian formulations. We show, analytically and numerically, that these formulations are equivalent and that they lead, in the limit of a plane-parallel atmosphere, to analytical expressions derived in previous works. As an example, we compute for a grey atmosphere intensity perturbations for low-degree solar oscillations and show that some p and g modes can produce large variations of intensity on the very limb of the solar disk. We also compute the corresponding flux perturbations showing that differences between spherical and plane-parallel computations for modes below 4 mHz do not exceed 15 percents, the better agreement being for low frequencies. Title: Magnetic Effects on Stellar Oscillations Authors: Bigot, L.; Provost, J.; Berthomieu, G.; Dziembowski, W. A.; Goode, P. R. Bibcode: 1999RoAJ....9S.129B Altcode: We calculate the effect of a strong dipole magnetic field (0.5-1.5 kG) on stellar oscillations. To do this, we adopt a boundary layer approach, by taking into account the dynamical effect of the magnetic field only in a very thin layer, at the star surface. The magnetic field leads to a damping of oscillations due to Alfvénic wave losses of energy. It appears then an imaginary part of the frequency (~1-15 ?Hz) and a shift of the real part (~1-15 ?Hz). The mode identification is complicated: since the Lorentz force depends on the colatitude, one must represent the oscillations by a linear combination of. We tackled non-axisymmetric oscillations (m0) and then generalized the result of Dziembowski and Goode (1996). These magnetic effects strongly depend on the geometric nature of the mode (degree and azimuthal order m). We apply our calculatio ns to roAp stars, whose oscillations appear essentially as dipole modes ( = 1, m = 0) aligned with the magnetic axis. This work does not explain this geometrical preference, since it does not minimize Alfvénic losses of energy. However, it shows that one must take into account the magnetic field to identify modes in roAp stars. Title: The acoustic cut-off frequency of roAp stars Authors: Audard, N.; Kupka, F.; Morel, P.; Provost, J.; Weiss, W. W. Bibcode: 1998A&A...335..954A Altcode: 1997astro.ph.12126A Some of the rapidly oscillating (roAp) stars, have frequencies which are larger than the acoustic cut-off frequency determined from published stellar models which usually assume a grey atmosphere. As the cut-off frequency depends on the T(tau ) relation, we have computed models and adiabatic frequencies for pulsating Ap stars with more realistic atmospheres which include a frequency dependent treatment of radiative transfer, take blanketing effects into account, and which have a better treatment of the radiative pressure. In addition, we are using opacity distribution functions specific to the atmospheric composition. With these improvements over the classical stellar models the theoretical acoustic cut-off frequency for roAp stars are increased by about 200 mu Hz, which brings them close to the observations. We restrict the comparison of our computations with observations to those two `pathological' roAp stars for which more reliable astrophysical parameters are available, HD 24712 and alpha Cir, and comment briefly on a third one, HD 134214. For alpha Cir we find models which have indeed a cut-off frequency beyond the largest observed frequency and which are well within the Teff - L/L_⊙ error box. For HD 24712 only models which are hotter by about 100 K and less luminous by nearly 10% than what is actually the most probable value derived by spectroscopy would have an acoustic cut-off frequency large enough. HD 134214 fits our models best, however, the error box for Teff - L/L_⊙ is the largest of all three stars. One may thus speculate that the old controversy about a mismatch between observed largest frequencies and theoretical cut-off frequencies of roAp star models is resolved. Based on hipparcos data. Title: Sensitivity of Low Frequency Oscillations to Updated Solar Models Authors: Provost, J.; Berthomieu, G.; Morel, P. Bibcode: 1998SSRv...85..117P Altcode: A large number of acoustic frequencies have already been detected, leading to a "seismic" model of the Sun rather close to the actual standard solar models. The core however is not yet well constrained by these observations and frequencies of low degree, low frequency modes which penetrate deeply into the solar core are needed. We present here a study on the sensitivity of low degree low frequency (50 - 900 µHz) modes to the structure of the solar interior, in order to help their detection and identification in the low frequency spectrum observed by SoHO experiments like VIRGO and GOLF. The frequencies of p and g modes have been computed for a set of solar models with updated physics (Morel et al., 1997). We analyze their sensitivity to solar parameters like age and metallicity, and to various physical processes, like convective core overshoot and mass loss during the beginning of solar evolution. Title: Atmospheric structure and acoustic cut-off frequency of roAp stars Authors: Audard, N.; Kupka, F.; Morel, P.; Provost, J.; Weiss, W. W. Bibcode: 1998CoSka..27..304A Altcode: 1998astro.ph..5091A Some of the rapidly oscillating (CP2) stars, have frequencies which are larger than the theoretical acoustic cut-off frequency. As the cut-off frequency depends on the T(tau) relation in the atmosphere, we have computed models and adiabatic frequencies for pulsating Ap stars with T(tau) laws based on Kurucz model atmospheres and on Hopf's purely radiative relation. The frequency-dependent treatment of radiative transfer as well as an improved calculation of the radiative pressure in Kurucz model atmospheres increase the theoretical acoustic cut-off frequency by about 200 microHz, which is closer to the observations. For alpha Cir we find models with Kurucz atmospheres which have indeed a cut-off frequency beyond the largest observed frequency and which are well within the T(eff) - L error box. For HD 24712 only models which are hotter by about 100 K and less luminous by nearly 10% than what is actually the most probable value would have an acoustic cut-off frequency large enough. One may thus speculate that the old controversy about a mismatch between observed largest frequencies and theoretical cut-off frequencies of roAp star models is resolved. However, the observational errors for the astrophysical fundamental parameters have to be reduced further and the model atmospheres refined. Title: Inferring the equatorial solar tachocline from frequency splittings Authors: Corbard, T.; Berthomieu, G.; Provost, J.; Morel, P. Bibcode: 1998A&A...330.1149C Altcode: 1997astro.ph.10319C Helioseismic inversions, carried out for several years on various ground-based and spatial observations, have shown that the solar rotation rate presents two principal regimes: a quasi-rigid rotation in the radiative interior and a latitude-dependent rotation in the whole convection zone. The thin layer, named solar tachocline, between these two regimes is difficult to infer through inverse techniques because of the ill-posed nature of the problem that requires regularization techniques which, in their global form, tend to smooth out any high gradient in the solution. Thus, most of the previous attempts to study the rotation profile of the solar tachocline have been carried out through forward modeling. In this work we show that some appropriate inverse techniques can also be used and we compare the ability of three 1D inverse techniques combined with two automatic strategies for the choice of the regularization parameter, to infer the solar tachocline profile in the equatorial plane. Our work, applied on LOWL (LOWL is an abbreviation for low degree denoted by L) two years dataset, argue in favor of a very sharp (0.05+/-0.03R_sun) transition zone located at 0.695+/-0.005R_sun which is in good agreement with the previous forward analysis carried out on Global Oscillations Network Group (GONG), Big Bear Solar Observatory (BBSO) and LOWL datasets. Title: Sensitivity of the Sound Speed to the Physical Processes Included in the Standard Solar Model Authors: Turck-Chièze, S.; Basu, S.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Gabriel, M.; Morel, P.; Provost, J.; Turcotte, S.; GOLF Team Bibcode: 1998ESASP.418..555T Altcode: 1998soho....6..555T The accuracy of the present seismic data allows us to check the solar internal sound speed down to the core. This is a great support to check the hypothesis of the classical stellar evolution and to predict the neutrino fluxes. The interpretation of these measurements supposes an accurate determination of the structure of the standard solar model as a first step. It is why a continuing effort has been devoted to the knowledge of the physical quantities included in this framework. In this poster we present 6 different solar models calculated by different groups of the GOLF consortium. These models include the most recent progress in atomic physics and nuclear physics. Then, we discuss the sensitivity of the sound speed difference, between GOLF+MDI observations and models, to different ingredients, in peculiar to the opacity coefficients and the determination of the solar age. Title: Solar Sound Speed Inferred from SOHO Helioseismic Data Authors: Gonczi, G.; Berthomieu, G.; Corbard, T.; Provost, J.; Morel, P.; GOLF Team Bibcode: 1998ESASP.418..461G Altcode: 1998soho....6..461G Inversions of the GOLF frequencies complemented with the 144 days MDI data have been performed to obtain the solar sound speed and density. We discuss the behavior of the sound speed in the solar core and in the tachocline relatively to the parameters of the inversion and to the solar model used. Title: Sounding solar and stellar interiors, IAU Symposium 181 (Posters) Authors: Provost, Janine; Schmider, Francois-Xavier Bibcode: 1998IAUS..181P....P Altcode: No abstract at ADS Title: The acoustic cut-off frequency of A to F stars Authors: Audard, N.; Kupka, F.; Morel, P.; Provost, J.; Weiss, W. W. Bibcode: 1998IAUS..185..299A Altcode: For some Ap stars, frequencies are observed which are larger than the theoretical acoustic cut-off frequency, which strongly depends on the T tau relation in the atmosphere. We have computed models and eigenmodes for pulsating Ap stars. The internal stellar structure is obtained with the CESAM code, and improved model atmospheres are constructed with T tau laws derived from Kurucz's model atmospheres. These models are compared to models whose atmospheres are derived from the purely radiative Hopf's T tau law. Our main result is that the frequency-dependent treatment of radiative transfer in Kurucz's model atmospheres induces an increase of the theoretical acoustic cut-off frequency, which brings us closer to the observations. As the cut-off frequency is determined by the very outer layers, we point out the necessity to compute very accurate model atmospheres. Title: Sensitivity of Low-frequency Oscillations to Updated Solar Models Authors: Provost, J.; Berthomieu, G.; Morel, P. Bibcode: 1998sce..conf..117P Altcode: No abstract at ADS Title: Observational Upper Limits for Low-Degree Solar g-modes Authors: Fröhlich, C.; Finsterle, W.; Andersen, B.; Appourchaux, T.; Chaplin, W. J.; Elsworth, Y.; D. O. Gough; Hoeksema, J. T.; Isaak, G. R.; Kosovichev, A. G.; Provost, J.; Scherrer, P. H.; Sekii, T.; Toutain, T. Bibcode: 1998ESASP.418...67F Altcode: 1998soho....6...67F No abstract at ADS Title: On the Use of Nonlinear Regularization in Inverse Methods for the Solar Tachocline Profile Determination Authors: Corbard, T.; Berthomieu, G.; Provost, J.; Blanc-Feraud, L. Bibcode: 1998ESASP.418..747C Altcode: 1998soho....6..747C; 1998astro.ph..6359C Inferring the solar rotation from observed frequency splittings represents an ill-posed problem in the sense of Hadamard and the traditional approach used to override this difficulty consists in regularizing the problem by adding some a priori information on the global smoothness of the solution defined as the norm of its first or second derivative. Nevertheless, inversions of rotational splittings (e.g. Corbard et al., 1998; Schou et al., 1998) have shown that the surface layers and the so-called solar tachocline (Spiegel & Zahn 1992) at the base of the convection zone are regions in which high radial gradients of the rotation rate occur. %there exist high gradients in the solar rotation profile near %the surface and at the base of the convection zone (e.g. Corbard et al. 1998) %in the so-called solar tachocline (Spiegel & Zahn 1992). Therefore, the global smoothness a-priori which tends to smooth out every high gradient in the solution may not be appropriate for the study of a zone like the tachocline which is of particular interest for the study of solar dynamics (e.g. Elliot 1997). In order to infer the fine structure of such regions with high gradients by inverting helioseismic data, we have to find a way to preserve these zones in the inversion process. Setting a more adapted constraint on the solution leads to non-linear regularization methods that are in current use for edge-preserving regularization in computed imaging (e.g. Blanc-Feraud et al. 1995). In this work, we investigate their use in the helioseismic context of rotational inversions. Title: How Solar Models Fit the SoHO Observations? Authors: Morel, P.; Provost, J.; Berthomieu, G. Bibcode: 1998ESASP.418..499M Altcode: 1998soho....6..499M Solar models are computed with CESAM code using different physical assumptions concerning the description of the surface layers, of the convection, of the screening and of the mass loss during the first stages of the evolution. The effect of the primeval evolution and of the uncertainties in the global constraints (age, present-days Z/X and radius values , protosolar abundances) are discussed. The agreement with the observations is estimated by comparison with seismic models derived from SoHO observations. Title: Comparative Studies of Low-Order and Low-Degree Solar p Modes Authors: Appourchaux, T.; Andersen, B.; Chaplin, W.; Elsworth, Y.; Finsterle, W.; Frohlich, C.; Gough, D.; Hoeksema, J. T.; Isaak, G.; Kosovichev, A.; Provost, J.; Scherrer, P.; Sekii, T.; Toutain, T. Bibcode: 1998ESASP.418...95A Altcode: 1998soho....6...95A The amplitudes of solar p-modes decrease steeply with decreasing radial order below about 17. The background solar signal (solar noise) in general increases steadily with decreasing frequency. For the irradiance and radiance measurements with VIRGO or SOI/MDI on SOHO this combination makes it difficult to detect low degree modes below about 1.8 mHz. The solar noise as observed in velocity with SOI/MDI or the ground based BISON network is significantly lower in this region than in intensity measurements. This allows low degree modes to be observed close to 1 mHz. We present results of detection and charaterization of the lowest order observable p-modes both in velocity and intensity measurements. Where applicable the properties of the modes observed with the two methods are compared. Title: Updated solar models. Authors: Morel, P.; Provost, J.; Berthomieu, G. Bibcode: 1997A&A...327..349M Altcode: 1997astro.ph..5251M Solar models computed with mass loss, microscopic diffusion of helium and heavy element, and with updated physics have been evolved from the pre-main sequence to present day; they are compared to the observational constraints including lithium depletion and to the seismic reference model of Basu et al. (1996ApJ...460.1064B), derived by inversion. Microscopic diffusion significantly improves the agreement with the observed solar frequencies and agree with the seismic reference model within +/-0.2% for the sound velocity and +/-1% for the density, but slightly worsens the neutrino problem. Neither microscopic diffusion nor overshooting explain the observed lithium depletion consistently with helioseismological constraints, while a mass loss process does it. Models computed with OPAL equation of state and opacities are in a better agreement with the seismic sound speed. To reach the level of precision of helioseismological observations the accuracy of solar models still needs to be improved by one order of magnitude; any such improvement will necessitate equation of state and opacity data taking into account of detailed changes in the mixture. Title: First View of the Solar Core from GOLF Acoustic Modes Authors: Turck-Chièze, S.; Basu, S.; Brun, A. S.; Christensen-Dalsgaard, J.; Eff-Darwich, A.; Lopes, I.; Pérez Hernández, F.; Berthomieu, G.; Provost, J.; Ulrich, R. K.; Baudin, F.; Boumier, P.; Charra, J.; Gabriel, A. H.; Garcia, R. A.; Grec, G.; Renaud, C.; Robillot, J. M.; Roca Cortés, T. Bibcode: 1997SoPh..175..247T Altcode: After 8 months of nearly continuous measurements the GOLF instrument, aboard SOHO, has detected acoustic mode frequencies of more than 100 modes, extending from 1.4 mHz to 4.9 mHz. In this paper, we compare these results with the best available predictions coming from solar models. To verify the quality of the data, we examine the asymptotic seismic parameters; this confirms the improvements achieved in solar models during the last decade. Title: Solar internal rotation from LOWL data. A 2D regularized least-squares inversion using B-splines. Authors: Corbard, T.; Berthomieu, G.; Morel, P.; Provost, J.; Schou, J.; Tomczyk, S. Bibcode: 1997A&A...324..298C Altcode: Observations of surface oscillations of the Sun can be analyzed to probe the solar interior. We use data obtained by the LOWL instrument (LOWL is an abbreviation for low degree with degree denoted by L) installed on Mauna Loa, Hawaii, since 1994 to investigate solar internal rotation. A 2 Dimensional Regularized Least-Squares (2D RLS) inverse method based on an expansion of the solution on B-splines of arbitrary order is presented and applied to a 2 year dataset. This method insures the regularity of the solution in the center and introduces surface constraints. The choice of trade-off parameters in the regularization term is discussed using an L-curves analysis and we discuss the influence of the choice of the order of derivatives in the regularization terms for the description of the deep interior. We study the latitudinal resolution of the inversion of a-coefficients compared to that of the inversion of individual splittings built from these coefficients. Compared to the previous inversion of the first three months of LOWL data made by Tomczyk et al. (1995ApJ...448L..57T), our solution is extended up to the surface by adding high degree modes and constraining the rotation to fit the spectrographic observations (Snodgrass, 1984SPh....94...13S). In the radiative zone we obtain more rigid rotation and our solution is compatible with a rotation of the solar core of the order or smaller than the surface rotation at mid latitude. Title: Theoretical solar models Authors: Provost, J. Bibcode: 1997IAUS..181..121P Altcode: No abstract at ADS Title: First results from VIRGO on SoHO Authors: Frohlich, C.; Andersen, B. N.; Appourchaux, T.; Berthomieu, G.; Crommelynck, D. A.; Domingo, V.; Fichot, A.; Finsterle, W.; Gómez, M. F.; Gough, D.; Jiménez, A.; Leifsen, T.; Lombaerts, M.; Pap, J. M.; Provost, J.; Roca Cortés, T.; Romero, J.; Roth, H. -J.; Sekii, T.; Telljohann, U.; Toutain, T.; Wehrli, C. Bibcode: 1997IAUS..181...67F Altcode: No abstract at ADS Title: Three years of ANTENA: what we have done! Authors: Belmonte, J. A.; Hernández, M. M.; Pérez Hernández, F.; Vidal, I.; Roca Cortés, T.; Michel, E.; Auvergne, M.; Chevreton, M.; Goupil, M. J.; Soufi, F.; Baglin, A.; Frandsen, S.; Viskum, M.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Schmider, F. X.; Fossat, E.; Delache, Ph.; Provost, J.; Audard, N.; Berthomieu, G.; Paparó, M.; Kovács, G.; Szabados, L. Bibcode: 1997IAUS..181..357B Altcode: No abstract at ADS Title: Sounding solar and stellar interiors Authors: Provost, Janine; Schmider, Francois-Xavier Bibcode: 1997IAUS..181.....P Altcode: No abstract at ADS Title: First Results from VIRGO, the Experiment for Helioseismology and Solar Irradiance Monitoring on SOHO Authors: Fröhlich, Claus; Andersen, Bo N.; Appourchaux, Thierry; Berthomieu, Gabrielle; Crommelynck, Dominique A.; Domingo, Vicente; Fichot, Alain; Finsterle, Wolfgang; Gómez, Maria F.; Gough, Douglas; Jiménez, Antonio; Leifsen, Torben; Lombaerts, Marc; Pap, Judit M.; Provost, Janine; Roca Cortés, Teodoro; Romero, José; Roth, Hansjörg; Sekii, Takashi; Telljohann, Udo; Toutain, Thierry; Wehrli, Christoph Bibcode: 1997SoPh..170....1F Altcode: First results from the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) on the ESA/NASA Mission SOHO (Solar and Heliospheric Observatory) are reported. The observations started mid-January 1996 for the radiometers and sunphotometers and near the end of March for the luminosity oscillation imager. The performance of all the instruments is very good, and the time series of the first 4-6 months are evaluated in terms of solar irradiance variability, solar background noise characteristics and p-mode oscillations. The solar irradiance is modulated by the passage of active regions across the disk, but not all of the modulation is straightforwardly explained in terms of sunspot flux blocking and facular enhancement. Helioseismic inversions of the observed p-mode frequencies are more-or-less in agreement with the latest standard solar models. The comparison of VIRGO results with earlier ones shows evidence that magnetic activity plays a significant role in the dynamics of the oscillations beyond its modulation of the resonant frequencies. Moreover, by comparing the amplitudes of different components ofp -mode multiplets, each of which are influenced differently by spatial inhomogeneity, we have found that activity enhances excitation. Title: The Current State of Solar Modeling Authors: Christensen-Dalsgaard, J.; Dappen, W.; Ajukov, S. V.; Anderson, E. R.; Antia, H. M.; Basu, S.; Baturin, V. A.; Berthomieu, G.; Chaboyer, B.; Chitre, S. M.; Cox, A. N.; Demarque, P.; Donatowicz, J.; Dziembowski, W. A.; Gabriel, M.; Gough, D. O.; Guenther, D. B.; Guzik, J. A.; Harvey, J. W.; Hill, F.; Houdek, G.; Iglesias, C. A.; Kosovichev, A. G.; Leibacher, J. W.; Morel, P.; Proffitt, C. R.; Provost, J.; Reiter, J.; Rhodes, E. J., Jr.; Rogers, F. J.; Roxburgh, I. W.; Thompson, M. J.; Ulrich, R. K. Bibcode: 1996Sci...272.1286C Altcode: Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations. Title: Differential Rotation and Dynamics of the Solar Interior Authors: Thompson, M. J.; Toomre, J.; Anderson, E. R.; Antia, H. M.; Berthomieu, G.; Burtonclay, D.; Chitre, S. M.; Christensen-Dalsgaard, J.; Corbard, T.; De Rosa, M.; Genovese, C. R.; Gough, D. O.; Haber, D. A.; Harvey, J. W.; Hill, F.; Howe, R.; Korzennik, S. G.; Kosovichev, A. G.; Leibacher, J. W.; Pijpers, F. P.; Provost, J.; Rhodes, E. J., Jr.; Schou, J.; Sekii, T.; Stark, P. B.; Wilson, P. R. Bibcode: 1996Sci...272.1300T Altcode: Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within the solar interior. The nearly uninterrupted observations by the Global Oscillation Network Group (GONG) yield oscillation power spectra with high duty cycles and high signal-to-noise ratios. Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths. A distinctive shear layer just below the surface is discernible at low to mid-latitudes. Title: VIRGO: Experiment for Helioseismology and Solar Irradiance Monitoring Authors: Fröhlich, Claus; Romero, José; Roth, Hansjörg; Wehrli, Christoph; Andersen, Bo N.; Appourchaux, Thierry; Domingo, Vicente; Telljohann, Udo; Berthomieu, Gabrielle; Delache, Philippe; Provost, Janine; Toutain, Thierry; Crommelynck, Dominique A.; Chevalier, André; Fichot, Alain; Däppen, Werner; Gough, Douglas; Hoeksema, Todd; Jiménez, Antonio; Gómez, Maria F.; Herreros, José M.; Cortés, Teodoro Roca; Jones, Andrew R.; Pap, Judit M.; Willson, Richard C. Bibcode: 1995SoPh..162..101F Altcode: The scientific objective of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) is to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations, to measure the solar total and spectral irradiance and to quantify their variability over periods of days to the duration of the mission. With these data helioseismological methods can be used to probe the solar interior. Certain characteristics of convection and its interaction with magnetic fields, related to, for example, activity, will be studied from the results of the irradiance monitoring and from the comparison of amplitudes and phases of the oscillations as manifest in brightness from VIRGO, in velocity from GOLF, and in both velocity and continuum intensity from SOI/MDI. The VIRGO experiment contains two different active-cavity radiometers for monitoring the solar `constant', two three-channel sunphotometers (SPM) for the measurement of the spectral irradiance at 402, 500 and 862 nm, and a low-resolution imager (LOI) with 12 pixels, for the measurement of the radiance distribution over the solar disk at 500 um. In this paper the scientific objectives of VIRGO are presented, the instruments and the data acquisition and control system are described in detail, and their measured performance is given. Title: Seismological comparison of giant planet interior models. Authors: Gudkova, T.; Mosser, B.; Provost, J.; Chabrier, G.; Gautier, D.; Guillot, T. Bibcode: 1995A&A...303..594G Altcode: We investigate the possibility to characterize the differences between interior models of Jupiter and Saturn with the help of seismological criteria. For both planets we consider two groups of models: first, models based on different descriptions of the hydrogen equation of state (plasma phase transition (PPT) or interpolated EOS) and second, models with different descriptions of the energy transport mechanism (fully convective models and radiative-convective models). The acoustic modes eigenfrequency patterns of both planets are calculated for the different models for degrees up to 30 (Jupiter) or 15 (Saturn), and for frequencies up to the tropospheric cutoff frequency. The different treatments of the hydrogen pressure ionization lead to substantial differences in the oscillation frequencies, up to 120μHz for Jupiter and 40μHz for Saturn. These variations come partly from the fact that the location of the rock/ice core depends strongly on the equation of state in the fluid envelope. The differences between the oscillation frequencies corresponding respectively to fully and non fully adiabatic models vary from 0 to 80μHz for Jupiter and to 40μHz for Saturn. This stems from the fact that the location of the PPT in the planetary interior and the core size depend strongly on the characteristics of the models. The amplitudes of the calculated variations suggest that future seismological observations should provide stringent tests to discriminate between various planetary interior models. Jupiter or Saturn may in fact be used as natural high-pressure laboratories to characterize the very nature of hydrogen pressure-metallization. Title: Predicted Intensity/velocity Amplitude and Phase Lag of Gravity Modes Authors: Toutain, T.; Berthomieu, J.; Provost, J.; Gouttebrouze, P. Bibcode: 1995ESASP.376b.419T Altcode: 1995soho....2..419T; 1995help.confP.419T No abstract at ADS Title: Nonadiabatic Computations of Solar P-Modes Authors: Gouttebroze, P.; Provost, J.; Berthomieu, G.; Toutain, T.; Morel, P. Bibcode: 1995ESASP.376b..53G Altcode: 1995soho....2...53G; 1995help.confP..53G A set of p-mode eigenfrequencies and eigenfunctions is computed both in adiabatic and nonadiabatic case, using different solar models. Concerning the treatment of radiation for the p-mode computations, the effects diffusion and Eddington approximations are compared. Convection effects are neglected, but the different formulations of the "frozen" convection approximation (e.g. Unno et al. 1989) are investigated. From the eigenfunctions so computed, the authors deduce the phase difference between intensity and Doppler shift variations integrated on the solar disk. The ratio of intensity to velocity amplitudes is also determined. Eigenfrequencies, phase differences and amplitude ratios are compared to available observations. Title: Solar Rotation from 2d Inversion Authors: Corbard, Th.; Berthomieu, G.; Gonczi, G.; Provost, J.; Morel, P. Bibcode: 1995ESASP.376b.289C Altcode: 1995soho....2..289C; 1995help.confP.289C No abstract at ADS Title: Seismological effects of convective-core overshooting in stars of intermediate mass. Authors: Audard, N.; Provost, J.; Christensen-Dalsgaard, J. Bibcode: 1995A&A...297..427A Altcode: We study the effects of convective-core overshooting on acoustic and gravity modes of low degree l for stars of intermediate mass. Using the CESAM code (Morel 1993) we have computed sequences of stars of 1.7 and 2Msun_ along the main sequence; both "classical" models, without overshooting, and models including convective overshooting from the core over 0.1 and 0.2 pressure scale-height are considered. We compare the structure and the oscillation properties of models of the same effective temperature. At given effective temperature, overshooting increases the stellar radius, and the main effect on oscillations is therefore to decrease the frequencies. This could give rise to a problem of the identification of the radial order of modes. The effects of overshooting on the deep stellar structure can be examined through different frequency combinations. In particular, the ratio (ν_n,0_+ν_n-1,0_-2ν_n-1,1_)/(ν_n,0_-ν_n-1,2_) (where ν_n,l_ is the cyclic frequency of a mode of radial order n and degree l) is very sensitive to the structure of the stellar core throughout the whole main sequence, and could therefore be a good indicator of the stellar age and of the extent of overshooting. The estimation of stellar mass and age from seismological observations is modified by convective core penetration, which must thus be taken into account for asteroseismological calibration. We furthermore study the evolution of p and g modes of low radial order along the main sequence, and exhibit the exchange of physical nature between pairs of modes whose frequencies approach very closely, related to the so-called avoided crossing. Convective core penetration makes avoided crossing occur at lower effective temperature, substantially changing the distribution of the kinetic-energy density of mixed modes throughout the stellar interior at a given effective temperature. Independently of overshooting, these modes have kinetic energy both in the central and external parts, and their observation would provide a powerful tool for probing the deep interior of stars and for investigating the importance of convective-core overshooting. Title: Neutrino Capture Rates Predicted by Standard Solar Models Authors: Berthomieu, G.; Provost, J.; Morel, P. Bibcode: 1995ASPC...76..109B Altcode: 1995gong.conf..109B No abstract at ADS Title: A New TEchnology Network for Asteroseismology - A.N.T.E.N.A. Authors: Roca Cortes, T.; Belmonte, J. A.; Delache, P.; Michel, E.; Frandsen, S.; Schmider, F. X.; Auvergne, M.; Fossat, E.; Vidal, I.; Kjeldsen, H.; Douglas, N.; Lelievre, G.; Chevreton, M.; Vauclair, G.; Audard, N.; Baglin, A.; Berthomieu, G.; Christensen-Dalsgaard, J.; Dolez, N.; Goupil, M. J.; Perez Hernandez, F.; Pfeiffer, B.; Provost, J.; Viskum, M. Bibcode: 1995ASPC...76..630R Altcode: 1995gong.conf..630R No abstract at ADS Title: Low Temperature Opacities Applied to Solar Calibrated Models Authors: Neuforge, C.; Provost, J.; Berthomieu, G.; Morel, P. Bibcode: 1995ASPC...78...75N Altcode: 1995aapn.conf...75N No abstract at ADS Title: Lithium Depletion in the Sun Authors: Morel, P.; Provost, J.; Berthomieu, G.; Matias, J.; Zahn, J. P. Bibcode: 1995LIACo..32..395M Altcode: 1995sews.book..395M No abstract at ADS Title: On the Solar Core Rotation - IRIS Results Authors: Fossat, E.; Loudagh, S.; Gelly, B.; Grec, G.; Pantel, A.; Provost, J.; Berthomieu, G.; Ehgamberdiev, S.; Khalikov, S.; Lazrek, M.; Palle, P. L.; Regulo, C. Bibcode: 1995ASPC...76...24F Altcode: 1995gong.conf...24F No abstract at ADS Title: Probing Convective-Core Overshooting through Seismology of Intermediate-Mass Stars Authors: Audard, N.; Provost, J. Bibcode: 1995ASPC...76..645A Altcode: 1995gong.conf..645A No abstract at ADS Title: On the Solar Core Rotation - IRIS Results Authors: Fossat, E.; Loudagh, S.; Gelly, B.; Grec, G.; Panel, A.; Provost, J.; Berthomieu, G.; Ehgamberdiev, S.; Khalikov, S.; Lazrek, M.; Palle, P. L.; Regulo, C. Bibcode: 1995ASPC...76....4F Altcode: No abstract at ADS Title: Diffusion phenomena and probabilistic methods Authors: Provost, J. -P. Bibcode: 1995cdhs.conf....1P Altcode: No abstract at ADS Title: About solar model calibration. Authors: Morel, P.; Berthomieu, G.; Provost, J.; Lebreton, Y. Bibcode: 1995LNP...458..197M Altcode: A new value of the ratio of the heavy elements content to hydrogen abundance Z/X has been recently estimated in the solar atmosphere. The authors present the consequences of this result on the solar standard model and examine the sensitivity to Z/X of the solar neutrinos flux predictions and of the oscillation frequencies. Title: Convective Penetration in the Sun in Presence of Microscopic Diffusion Authors: Provost, J.; Morel, P.; Berthomieu, G.; Zahn, J. P. Bibcode: 1995LIACo..32..201P Altcode: 1995sews.book..201P No abstract at ADS Title: On P-mode oscillations in stars from 1M ⊙ to 2M ⊙ Authors: Audard, N.; Provost, J. Bibcode: 1994SoPh..152..316A Altcode: 1994IAUCo.143..316A; 1994svs..coll..316A The structure of stars more massive than about 1.2M⊙ is characterized by a convective core. We have studied the evolution with age and mass of acoustic frequencies if high radial ordern and low degree ℓ for models of stars of 1, 1.5 and 2M⊙. Using a polynomial approximation for the frequency, the p-mode spectrum can be characterized by derived global asteroseimic coefficients, i.e. the mean separationv0∼vn,ℓ−vn,−1,ℓ and the small frequency separationΔv0,2∼vn,ℓ=0−vn,−1,ℓ=2. The diagram(v0,Δ(v0,2/v0 plotted along the evolutionary tracks would help to separate the effects of age and mass. We study of sensitivity of these coefficients and other observable quantities, like the radius and luminosity, the stellar parameters in the vicinity of 1M⊙ and 2M⊙; this sensitivity substantially depends on the stellar mass and must be taken into account for asteroseismic calibration of stellar clusters. Considering finally some rapid variations of the internal structure, we show that the second frequency differenceδ2v=vn,ℓ−2vn,−1,ℓ+vn,−2,ℓ exhibits and oscillatory behaviour well related to the rapid variation of the adiabatic exponent γ in the HeII ionization zone. Title: Incorporating the atmosphere in stellar structure models: the solar case Authors: Morel, P.; van't Veer, C.; Provost, J.; Berthomieu, G.; Castelli, F.; Cayrel, R.; Goupil, M. J.; Lebreton, Y. Bibcode: 1994A&A...286...91M Altcode: The diffusion limit of the transfer equation used in the calculations of stellar interior models is only valid at large Rosseland optical depth. From atmosphere models obtained with ATLAS 9 (Kurucz), it is shown here that the diffusion limit of the transfer equation becomes valid only at Rosseland optical depths τ_R_ >~ 10 that is at a location well inside the Sun's convective zone. For the calculations of stellar evolution, the atmosphere is built from T(τ) laws that are derived either from theory or from full atmosphere computations; such a T(τ) law depends upon effective temperature and gravity, therefore on the evolutionary state of the model. Hence, in general, when following the evolution of a star, various T(τ) laws need to be introduced. In the case of the Sun, however, we show here that the atmosphere can be restored with the use of only one T(τ) law. Particular efforts have been made to include physics as consistent as possible in both the model atmosphere from which one derives T(τ) laws and the internal structure calculations which use them; as a result, we can rebuild the atmosphere in stellar models with an accuracy of about +/- 0.5% for the sound speed and the pressure. Remaining discrepancies are of small effect on solar calibrated models. For the solar oscillations, such small discrepancies generate frequency differences no larger than 2μHz for low degrees modes to about 10μHz for modes of large degrees around 400. Title: Jovian seismology: influence of the troposphere thermal signature and seismological diagnosis Authors: Gudkova, T.; Mosser, B.; Gautier, D.; Guillot, T.; Provost, J.; Chabrier, G. Bibcode: 1994DPS....26.1307G Altcode: 1994BAAS...26.1109G No abstract at ADS Title: Seismological properties of intermediate-mass stars Authors: Audard, N.; Provost, J. Bibcode: 1994A&A...282...73A Altcode: Stars more massive than about 1.2 solar mass are characterized by a convective core, which induces at its frontier a rapid variation of the density, sound speed and Brunt-Vaisala frequency, close to a discontinuity. For three stars of 1, 1.5 and 2 solar mass we have studied the properties of p-mode frequencies of high radial order and low degree, and we present results on the effects on p-mode oscillations of some rapid variations of the internal structure. We first point out the difficulties of the classical asymptotic theory to represent with accuracy the p-mode spectrum of the stars considered. We compare the numerical frequencies with asymptotic and polynomial approximations obtained from fits. The variation of the derived global coefficients characterizing the p-mode spectrum along the evolutionary tracks has been estimated; it would help to separate the effects of age and mass of intermediate-mass stars. The sensitivity of these coefficients to stellar parameters substantially depends on the stellar mass and must be considered for asteroseismic calibration. The effects of rapid variations in the stellar internal structure are finally considered. An asymptotic formula taking into account the rapid variation of the sound speed at the convective core boundary of the 1.5 and 2 solar mass stars predicts an oscillatory behavior of the frequencies with a very large period. We also show that the second frequency difference delta2nu = nun, l - 2nun-1, l + nun-2, l exhibits a substantial oscillation which corresponds to the region of the He II ionization of the 1, 1.5 and 2 solar mass stars. Title: On the equation of state in Jovian seismology Authors: Provost, J.; Mosser, B.; Chabrier, G. Bibcode: 1994esa..conf..596P Altcode: 1994IAUCo.147..596P No abstract at ADS Title: Symplectic geometry and physics: three introductory lectures. Authors: Provost, J. -P. Bibcode: 1994mcag.conf..209P Altcode: Contents: Lecture I: geometry and physics. Lecture II: the occurrence of symplectic geometry in optics and mechanics. Lecture III: three applications of symplectic geometry. Epilog: the cat's paradigm. Title: Standard Solar Models with CESAM Code: Neutrinos and Helioseismology Authors: Berthomieu, J.; Provost, J.; Morel, P.; Lebreton, Y. Bibcode: 1994snft.book...62B Altcode: No abstract at ADS Title: The solar interior Authors: Turck-Chièze, S.; Däppen, W.; Fossat, E.; Provost, J.; Schatzman, E.; Vignaud, D. Bibcode: 1993PhR...230...57T Altcode: This report confronts the different aspects of the solar interior from the experimental and theoretical points of view, discussing photospheric abundances, neutrinos and acoustic mode measurements. The theoretical approach mainly concerns the classical framework of stellar evolution, nevertheless, particle interpretation of the data and astrophysical solutions invoked in the last 10 years are coherently examined. Title: A measurement of the I = I solar rotational splitting Authors: Loudagh, S.; Provost, J.; Berthomieu, G.; Ehgamberdiev, S.; Fossat, E.; Gelly, B.; Grec, G.; Khalikov, S.; Lazrek, M.; Palle, P.; Regulo, C.; Sanchez, L.; Schmider, F. -X. Bibcode: 1993A&A...275L..25L Altcode: A precise measurement of the l = 1 rotational splitting has been derived from the 1991 IRIS data and it leads to a moderate rotation rate in the solar core. Title: A New Asymptotic Formalism for Jovian Seismology Authors: Provost, J.; Mosser, B.; Berthomieu, G. Bibcode: 1993A&A...274..595P Altcode: In order to account for the core of the giant planets interior, a second order asymptotic formalism has been adapted to Jovian seismology, for low degree high frequency acoustic modes, starting from the work of Tassoul (1980). We consider a spherical non-rotating model of Jupiter presenting a strong discontinuity in density and sound speed at the core frontier. We exhibit a peculiar behavior of the pressure modes eigenfrequency pattern. Contrarily to the solar case, eigenfrequencies are not almost equidistant, and this has to be taken into account when interpreting an observed spectrum. A qualitative agreement with the frequencies computed from a planetary model is obtained. Therefore we use the asymptotic formalism to compare actual Jovian interior models. The formalism developed here is applicable to any non rotating object presenting a noncontinuous interior, provided the asymptotic constraints are fulfilled. The limit of validity of this formalism is discussed in the context of Jovian seismology. Title: Standard solar models with CESAM code - Neutrinos and helioseismology Authors: Berthomieu, G.; Provost, J.; Morel, P.; Lebreton, Y. Bibcode: 1993A&A...268..775B Altcode: A new code for stellar evolution named CESAM has been constructed and standard solar models have been computed using it. Their global characteristics, predicted capture rates of neutrinos for the chlorine and gallium experiments, and their seismological properties are given and compared to the observational constraints. The emphasis is put on the effect of the recent opacities of Livermore for different mixtures, corresponding to recent abundances determination, and on the neutrino predictions and solar oscillations. Title: Restoration of the atmosphere in solar models Authors: Morel, P.; van't Veer, C.; Berthomieu, G.; Cayrel, R.; Castelli, F.; Goupil, M. J.; Lebreton, Y.; Provost, J. Bibcode: 1993ASPC...40...57M Altcode: 1993IAUCo.137...57M; 1993ist..proc...57M No abstract at ADS Title: CESAM solar models Authors: Morel, P.; Berthomieu, G.; Provost, J.; Lebreton, Y. Bibcode: 1993ASPC...40...54M Altcode: 1993ist..proc...54M; 1993IAUCo.137...54M No abstract at ADS Title: About seismological properties of intermediate mass stars Authors: Audard, N.; Provost, J. Bibcode: 1993ASPC...40..544A Altcode: 1993ist..proc..544A; 1993IAUCo.137..544A No abstract at ADS Title: Seismological constraints on convective penetration in the Sun. Authors: Berthomieu, G.; Morel, P.; Provost, J.; Zahn, J. -P. Bibcode: 1993ASPC...40...60B Altcode: 1993IAUCo.137...60B; 1993ist..proc...60B Penetrative convection is expected below stellar convection zones, where it should achieve a nearly adiabatic stratification. A theoretical prediction of the penetration depth has been recently made by Zahn (1991) which includes an arbitrary parameter ζ depending on the properties of the convective motions. The authors use the helioseismological constraints to calibrate the value of this parameter. Title: Convective Penetration in the Sun Authors: Berthomieu, G.; Morel, P.; Provost, J.; Zahn, J. -P. Bibcode: 1992ASPC...26..158B Altcode: 1992csss....7..158B No abstract at ADS Title: The Spectrum of Gravity Modes as a Function of the Solar Structure - Model with a Mixed Core Authors: Provost, J.; Gavryuseva, E.; Gavryusev, V.; Berthomieu, G. Bibcode: 1991SoPh..133..139P Altcode: The asymptotic properties of the gravity modes of solar models with a mixed core have been investigated. Such models have been constructed by Gavryusev and Gavryuseva (1984) to explain the low value of the observed neutrino flux (Cleveland, Davis, and Rowly, 1984). The strong enhancement of the Brunt-Väissälä frequency in the region of variable chemical composition at the boundary of the mixed core gives rise to a nonequidistant spectrum of gravity mode periods (Figure 1), contrary to the case of `standard' models. These models do not satisfy the helioseismological constraints given by the p-modes. However, the peculiar behavior of the numerically computed periods of the gravity modes is interesting to analyze, in view of observational detection in solar and stellar spectra. Title: The asymptotic spectrum of gravity modes as a function of the solar structure: Standard solar model Authors: Berthomieu, G.; Provost, J. Bibcode: 1991SoPh..133..127B Altcode: Some results are given on the properties of the second-order asymptotic expression of the periods of low-degree gravity modes and on their rotational splitting. These could be of some help for the detection of these modes in the signal. Title: On the visibility of low frequency nonradial pulsations for a grey solar atmosphere Authors: Provost, J.; Berthomieu, G. Bibcode: 1991AdSpR..11d..39P Altcode: 1991AdSpR..11...39P The visibility of low-frequency nonradial solar oscillations with respect to their degree and frequency is examined in the framework of ground-based and space-based helioseismology experiments. Two effects leading to the variation of the observed flux are examined: wave-induced temperature variation and opacity variation. The effect of the wave-induced opacity perturbation on the intensity fluctuation of gravity modes is considered in the grey-atmosphere approximation for both adiabatic and nonadiabatic modes. Title: Héliosismologie: théorie. Authors: Berthomieu, G.; Provost, J. Bibcode: 1991sed..conf...77B Altcode: Contents: (1) Oscillations adiabatiques d'un modèle solaire: (A) Propriétés générales. (B) Description asymptotique des modes de pression et de gravité. (2) Structure du soleil déduite des observations. (A) Méthode directe: sensibilité au modèle. (B) Méthode inverse. (3) La rotation solaire. (A) Effet de la rotation sur les fréquences d'oscillation. (B) Les coefficients ai comme mesure du splitting des fréquences. (C) Inversion de la rotation solaire. Résultats. Title: Non-Equidistant Spectrum of Gravity Modes of a Solar Model with a Mixed Core Authors: Provost, J.; Berthomieu, G.; Gavriuseva, E.; Gavriusev, V. Bibcode: 1990SoPh..128..111P Altcode: 1990IAUCo.121P.111P The asymptotic properties of the gravity modes of solar models with a mixed core have been investigated. In this model, the Brunt-Väissälä frequency has a strong enhancement in the region of variable chemical composition at the boundary of the mixed core, giving rise to a non-equidistant spectrum of gravity modes periods. An asymptotic expression for the periods is derived, which relates the main feature of the departure from period equidistance to the stratification of the model. Qualitative agreement with the numerical periods of the model is obtained. Title: Investigation on Numerical Accuracy of ZAMS Models of One Solar Mass Authors: Morel, P.; Provost, J.; Berthomieu, G. Bibcode: 1990SoPh..128....7M Altcode: 1990IAUCo.121P...7M Helioseismology requires solar models computed with great accuracy. Results of investigations about the incidence in ZAMS models of one solar mass of the numerical errors arising from the interpolation of opacity tables and from the integration of the atmosphere are reported. Title: Light and velocity visibility of solar g-mode oscillations Authors: Berthomieu, G.; Provost, J. Bibcode: 1990A&A...227..563B Altcode: The properties of the integrated intensity and velocity variations of the solar gravity modes in the 40 to 130 microHz frequency range are given in the adiabatic and nonadiabatic case. Grey atmosphere and Eddington approximations have been used as a first step. Equipartition of the energy has been assumed in order to give an estimation of the amplitudes. For integration over the whole disk, low degree models l = 1, 2 have the highest amplitudes due to the spatial filtering, but a decrease of this amplitude appears in the range 60 to 80 microHz due to the intrinsic properties of the waves. Title: Integrated light and velocity of solar g modes oscillations. Authors: Provost, J.; Berthomieu, G. Bibcode: 1988ESASP.286..387P Altcode: 1988ssls.rept..387P The properties of the integrated intensity and velocity variations of the solar gravity modes for different spatial filters are studied in the adiabatic and nonadiabatic cases in the frequency range 40 - 120 μHz. Predicted amplitudes are given assuming equipartition of energy between the modes. As far as the intensity is concerned, a lack of amplitude has been pointed out around 60 μHz, which should have implication on the whole disc Virgo and ground based observations. Title: Influence of the axial-vector coupling constant on solar models - Solar neutrino fluxes, helium content and oscillations Authors: Lebreton, Y.; Schatzman, E.; Berthomieu, G.; Provost, J. Bibcode: 1988A&A...200L...5L Altcode: This paper examines the effects of axial-vector coupling constant g(A) changes on the outputs of solar-models (such as helium content, neutrino fluxes, and oscillations), using existing 'calibrated' solar models and assuming that the other inputs of the models are well-known. The results suggest that a very high value of g(A) (greater than 1.55) is required to reconcile the theoretical and observed neutrino fluxes. This value seems to be improbable with respect to the present range of measurements of g(A); moreover, a solar model with such a high value of g(A) is associated to a helium content that is above the usually accepted value. Title: A Solar Model with Turbulent Diffusion Mixing - Surface Abundances and Oscillations Authors: Lebreton, Y.; Berthomieu, G.; Provost, J. Bibcode: 1988IAUS..123...95L Altcode: A solar model which includes the plausible presence of a mild mixing in the solar inner radiative zone is presented. The model takes into account the inhibition of turbulent motions. The properties of the model are compared to the standard model properties and to observational results: the turbulent diffusion mixing (TDM) improves the results on surface abundances of the light elements (7Li, 3He) and does not reduce the solar neutrino flux relative to the standard model. Moreover, the TDM weakly modifies the oscillation frequencies. Title: Asymptotic Properties of Low Degree Gravity Modes Authors: Berthomieu, G.; Provost, J. Bibcode: 1988IAUS..123..121B Altcode: Asymptotic properties of low degree gravity modes and their relation to the stratification of the model through the Brunt-Väissälä frequency are discussed for a solar type model and for a 10 M_sun; model. Title: Effective Operators in Charge Exchange Studies Authors: Levy, B.; Provost, J.; Roueff, E. Bibcode: 1987IAUS..120...25L Altcode: The rate coefficient for the charge transfer reaction C++H→C+H+ is calculated with the introduction of the radial coupling between the two 3π states arising from both asymptotic atomic states. The derived rate coefficient at a temperature of 104K is 2×10-15cm3s-1 which is two orders of magnitude larger than the value previously estimated by Butler and Dalgarno (1980) from a weak spin orbit coupling between the 3Σ- and 3Σ+ molecular states of CH+. Title: Asymptotic properties of low degree solar gravity modes Authors: Provost, J.; Berthomieu, G. Bibcode: 1986A&A...165..218P Altcode: The application of the second-order asymptotic theory of Tassoul (1980) to the low degree solar gravity modes is discussed. The standard solar model of Schatzmann and Maeder (1981) is used to compute a set of g-mode periods, and the possibility of recovering the coefficients of the expression derived previously for the g-modes by a least square analysis on the set of computed periods is tested. The coefficients given by least squares analysis are compared to their values estimated from the model. It is shown that, within the range of computed periods, it is possible to recover some constraints on the solar interior and that very large periods are required to derive the properties of the stratification just below the convection zone. Title: Sismologie stellaire: problème direct. Authors: Berthomieu, G.; Provost, J. Bibcode: 1986mma..conf..525B Altcode: No abstract at ADS Title: Influence of turbulent diffusion on asymptotic low degree solar gravity modes Authors: Berthomieu, G.; Provost, J.; Schatzman, E. Bibcode: 1984MmSAI..55..107B Altcode: The characteristic period P(0) separating the low-frequency solar g-modes of the same (low) degree is calculated theoretically using several published models of solar structure, and these model values of P(0) are compared with observations. The asymptotic properties of g-modes are reviewed, and the influence of turbulent mixing is studied by comparing the predictions of the models of Schatzmann and Maeder (1981) for pseudo-Reynolds numbers zero, 100, and 200. It is found that the observed P(0) values (about 38.8 or 41 min) are consistent with a moderate pseudo-Reynolds number, which can also account for the surface He-3/He-4 ratio and Li depletion but conflicts with neutrino-flux data. Title: Solar gravity modes as a test of turbulent diffusion mixing Authors: Berthomieu, G.; Provost, J.; Schatzman, E. Bibcode: 1984Natur.308..254B Altcode: The Stanford group1 has recently detected solar global oscillations in the range 160-370 min and interpreted them as internal gravity modes of degree l = 1 and l = 2. Other observations2,3 also indicate the existence of low-degree solar gravity modes. Whereas the high-degree 5-min oscillations are sensitive to the properties of the convective zone essentially, the low-frequency modes (gravity modes) are sensitive to the physical conditions in the solar core. Other constraints on the solar core are given by the observed value of the neutrino flux, which is lower than the flux predicted by the standard models, and by the splitting of the low-degree 5-min oscillations. As far as the neutrino flux is concerned, a possibility to reduce it has been explored by Schatzman and Maeder4 by introducing a turbulent diffusion mixing. In this paper we study the influence of such mixing on the periods of low-degree l gravity modes, which do not present the difficulties of the high-degree gravity modes5. We find that these periods depend strongly on the pseudo-Reynolds number4, and we derive the range of this parameter compatible with the recent observational results. Title: Solar Constraints Authors: Provost, J. Bibcode: 1984IAUS..105...47P Altcode: Accurate tests of the theory of stellar structure and evolution are available from the Sun's observations. The solar constraints are reviewed, with a special attention to the recent progress in observing global solar oscillations. Each constraint is sensitive to a given region of the Sun. The present solar models are discussed with respect to neutrino flux, low and high degree five-minute oscillations and low degree internal gravity modes. It appears that actually there do not exist solar models able to fully account for all the observed quantities. Title: Excitation of Non-Adiabatic Quasi-Toroidal Oscillations in Double Stars Authors: Provost, J.; Berthomieu, G.; Rocca, A. Bibcode: 1984LIACo..25..372P Altcode: 1984trss.conf..372P; 1984tpss.conf..372P No abstract at ADS Title: Turbulent Diffusion Mixing - Solar and Stellar Constraints Authors: Berthomieu, G.; Provost, J.; Schatzman, E. Bibcode: 1984apoa.conf..189B Altcode: No abstract at ADS Title: Non-adiabatic quasi-toroidal modes in a slowly rotating star : application to ZZ Ceti. Authors: Berthomieu, G.; Provost, J. Bibcode: 1983A&A...122..199B Altcode: A linear adiabatic and non-adiabatic analysis of the quasi-toroidal modes of a uniformly slowly rotating star is presented and applied to chemically stratified DA white dwarfs. These modes are unstable for sufficiently high values of the rotation of the star and in some range of the effective temperature and of the amount of hydrogen in the outer envelope. The destabilizing mechanism and the instability strip are the same as for the gravity modes considered by Dolez and Vauclair (1981), but the growth rates are much smaller. Title: Les oscillations solaires et stellaires comme test de la théorie de la structure interne. Authors: Provost, J. Bibcode: 1983ihaa.conf..167P Altcode: Contents: Introduction. Quelques propriétés théoriques des oscillations stellaires. Les oscillations solaires et leur interprétation. Perspectives de développement de la sismologie solaire et stellaire. Title: Low Frequency Oscillations of a Slowly Rotating Star - Quasi Toroidal Modes Authors: Provost, J.; Berthomieu, G.; Rocca, A. Bibcode: 1981A&A....94..126P Altcode: The radial structure and the frequencies of the nonaxisymmetric quasi-toroidal modes of a slowly rotating star have been computed in the case of rigid rotation. The main results are that these modes may have a significant amplitude in the interior of the star and that they are greatly influenced by the non-sphericity of the star. Title: Quasi Toroidal Modes in B-Stars Authors: Berthomieu, G.; Provost, J.; Groupe Etoiles Variables de L'Observatoire de Nice Bibcode: 1981pbs..work..337B Altcode: No abstract at ADS Title: Theoretical Prediction of Eigen Frequencies of the Solar Five Minute Oscillation Authors: Berthomieu, G.; Cooper, A. J.; Gough, D. O.; Osaki, Y.; Provost, J.; Rocca, A. Bibcode: 1980jfss.conf...32B Altcode: No abstract at ADS Title: Sensitivity of five minute eigenfrequencies to the structure of the sun Authors: Berthomieu, G.; Provost, J.; Rocca, A.; Cooper, A. J.; Gough, D. O.; Osaki, Y. Bibcode: 1980LNP...125..307B Altcode: 1980nnsp.work..307B The dependence of theoretical eigenfrequencies of five minute oscillation modes on the parameters that determine model solar envelopes has been investigated. It was found that the p mode frequencies are quite strongly correlated with the depth of the convection zone. Comparison of theory with observation suggests that the solar convection zone is about 200,000 km deep. Title: Wave Reflections in the Solar Atmosphere Authors: Provost, J.; Mein, N. Bibcode: 1979SoPh...64...43P Altcode: The small phase-lag between velocities observed at different chromospheric levels is interpreted as being due to acoustic waves reflected by the very hot atmospheric layers of the chromosphere-corona transition zone. We consider first an isothermal slab, then a realistic solar atmospheric model and calculate weighting functions for velocities in Ca II lines. It is shown that taking into account these functions and integrating over horizontal wave numbers leads to a good agreement with previous observations (Mein, 1977) in the case of 8498 and 8542 Ca II lines. For the K line, the less good agreement shows that magnetoacoustic waves become important in the upper chromospheric layers. Title: Low-frequency Gravity Modes of a Rotating Star Authors: Berthomieu, G.; Gonczi, G.; Graff, Ph.; Provost, J.; Rocca, A. Bibcode: 1978A&A....70..597B Altcode: Summary. The frequencies of gravity modes of a slowly rotating star have been calculated by an asymptotic method in the case where the frequencies of the modes are of the same order than the angular rotation speed. It is shown that the distortion of the star can then be neglected. A general relationship is established between the eigenfrequencies and the rotation in the limit of a large number of radial nodes. Key Words. non-radial oscillations - stellar rotation Title: Propagation of an optically thin isothermal perturbation in an atmosphere traversed by a radiation field. Authors: Berthomieu, G.; Provost, J.; Rocca, A. Bibcode: 1976A&A....47..413B Altcode: The propagation of optically thin isothermal perturbations in an isothermal slab of an atmosphere traversed by a radiation flux is considered. Such perturbations are amplified during their propagation up to a finite limit which is a function of the effective gravity, and which becomes infinite only in the rather unrealistic case where this effective gravity is zero. Although this result depends on the assumption made for the absorption coefficient, it shows that a nonlocal analysis of the amplification is needed in order to be able to apply it to the chromospheric heating of hot stars, a mechanism suggested by Hearn (1972). Title: Filtering of acoustic waves in the solar atmosphere. Authors: Provost, J. Bibcode: 1976A&A....46..159P Altcode: The evolution with height of the power spectrum of the response of the solar atmosphere to an excitation in a wide range of frequencies is discussed. It is found that the layers under the photosphere enhance a range of periods around 300 s, while the photospheric and low chromospheric layers enhance 150-200 s periods. Linear filtering appears to be a process relevant for the understanding of major characteristics of solar atmospheric dynamics. Title: Filtering of acoustic waves in the solar atmosphere Authors: Provost, J. Bibcode: 1976pmas.conf..281P Altcode: No abstract at ADS Title: Response of a Bounded Atmosphere to a Non-Resonant Excitation. I: Isothermal Case Authors: Provost, J. Bibcode: 1975SoPh...40..257P Altcode: The response of a bounded atmosphere to a non-resonant excitation applied at its basis is studied. It is shown that the essential feature related to this kind of excitation is that the distribution of the energy of the velocity field relatively to the frequency and horizontal wavelength is a function of height and merely depends on the structure of the atmosphere above the level at which it is considered. The preliminary results concerning an isothermal atmosphere are presented and their relevance to the solar case is discussed. Title: Note on the Response of an Atmosphere to a Localized Turbulent Source Authors: Provost, Janine Bibcode: 1973SoPh...33..103P Altcode: No abstract at ADS Title: A comparative detailed analysis of 22 Serpentis, a high metallicity A2 star, and the standard F0 V: 9 Aurigae. Authors: Provost, J.; van't Veer-Menneret, C. Bibcode: 1969A&A.....2..218P Altcode: From photometric studies and high resolution spectrography of 22 Ser, a supposed Am star, and of 9 Aur, a main sequence F0 star, we derive the following atmospheric parameters: for 22 Ser: Q =0.65, logg=4.44, for 9Aur: Q =O.7O, logg=4.44. Using the appropriate Mihalas models, a comparative study of the two stars by the method of differential curve of growth analysis confirms the Am character of 22 Ser by the high microturbulence velocity and the abundance anomalies found. The star 9 Aur shows a solar chemical composition, but a microturbulence velocity, of 4 km/s, which is too high for a main sequence F0 star. Key words: 22 Ser, 9 Aur, metaffic-line stars - detailed differential curve of growth analysis - multicolourphotometry - chemical composition - microturbulence velocity - abundance