Search

Your search keyword '"Baudin, F"' showing total 20 results
Start Over Author "Baudin, F" Topic astrophysics
20 results on '"Baudin, F"'

1. Oscillating red giants in the CoRoT exo-field: Asteroseismic mass and radius determination

Author

Kallinger, T., Weiss, W. W., Barban, C., Baudin, F., Carrier, F., Cameron, C., De Ridder, J., Goupil, M. -J., Gruberbauer, M., Hatzes, A., Hekker, S., Samadi, R., and Deleuil, M.

Subjects
Astrophysics
Abstract

Context. Observations and analysis of solar-type oscillations in red-giant stars is an emerging aspect of asteroseismic analysis with a number of open questions yet to be explored. Although stochastic oscillations have previously been detected in red giants from both radial velocity and photometric measurements, those data were either too short or had sampling that was not complete enough to perform a detailed data analysis of the variability. The quality and quantity of photometric data as provided by the CoRoT satellite is necessary to provide a breakthrough in observing p-mode oscillations in red giants. We have analyzed continuous photometric time-series of about 11 400 relatively faint stars obtained in the exofield of CoRoT during the first 150 days long-run campaign from May to October 2007. We find several hundred stars showing a clear power excess in a frequency and amplitude range expected for red-giant pulsators. In this paper we present first results on a sub-sample of these stars. Aims. Knowing reliable fundamental parameters like mass and radius is essential for detailed asteroseismic studies of red-giant stars. As the CoRoT exofield targets are relatively faint (11-16 mag) there are no (or only weak) constraints on the star's location in the H-R diagram. We therefore aim to extract information about such fundamental parameters solely from the available time series. Methods. We model the convective background noise and the power excess hump due to pulsation with a global model fit and deduce reliable estimates for the stellar mass and radius from scaling relations for the frequency of maximum oscillation power and the characteristic frequency separation., Comment: 10 pages, 7 figures, accepted for publication in A&A

Published
2008

2. Stochastic excitation of nonradial modes II. Are solar asymptotic gravity modes detectable?

Author

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

Subjects
Astrophysics
Abstract

Detection of solar gravity modes remains a major challenge to our understanding of the innerparts of the Sun. Their frequencies would enable the derivation of constraints on the core physical properties while their amplitudes can put severe constraints on the properties of the inner convective region. Our purpose is to determine accurate theoretical amplitudes of solar g modes and estimate the SOHO observation duration for an unambiguous detection. We investigate the stochastic excitation of modes by turbulent convection as well as their damping. Input from a 3D global simulation of the solar convective zone is used for the kinetic turbulent energy spectrum. Damping is computed using a parametric description of the nonlocal time-dependent convection-pulsation interaction. We then provide a theoretical estimation of the intrinsic, as well as apparent, surface velocity. Asymptotic g-mode velocity amplitudes are found to be orders of magnitude higher than previous works. Using a 3D numerical simulation, from the ASH code, we attribute this to the temporal-correlation between the modes and the turbulent eddies which is found to follow a Lorentzian law rather than a Gaussian one as previously used. We also find that damping rates of asymptotic gravity modes are dominated by radiative losses, with a typical life-time of $3 \times 10^5$ years for the $\ell=1$ mode at $\nu=60 \mu$Hz. The maximum velocity in the considered frequency range (10-100 $\mu$Hz) is obtained for the $\ell=1$ mode at $\nu=60 \mu$Hz and for the $\ell=2$ at $\nu=100 \mu$Hz. Due to uncertainties in the modeling, amplitudes at maximum i.e. for $\ell=1$ at 60 $\mu$Hz can range from 3 to 6 mm s$^{-1}$., Comment: 18 pages, 19 figures, accepted for publication in Astronomy & Astrophysics

Published
2008
Full Text
View/download PDF

3. Intrinsic photometric characterisation of stellar oscillations and granulation. Solar reference values and CoRoT response functions

Author

Michel, E., Samadi, R., Baudin, F., Barban, C., Appourchaux, T., and Auvergne, M.

Subjects
Astrophysics
Abstract

Context: Measuring amplitudes of solar-like oscillations and the granulation power spectral density constitute two promising sources of information to improve our understanding and description of the convection in outer layers of stars. However, different instruments, using different techniques and different bandpasses, give measurements that cannot be directly compared to each other or to theoretical values. Aims: In this work, we define simple response functions to derive intrinsic oscillation amplitudes and granulation power densities, from photometry measurements obtained with a specific instrument on a specific star. Methods: We test this method on different photometry data sets obtained on the Sun with two different instruments in three different bandpasses. Results: We show that the results are in good agreement and we establish reference intrinsic values for the Sun with photometry. We also compute the response functions of the CoRoT instrument for a range of parameters representative of the Main Sequence solar-like pulsators to be observed with CoRoT. We show that these response functions can be conveniently described by simple analytic functions of the effective temperature of the target star., Comment: 6 pages, 7 figures. Updated title and abstract

Published
2008
Full Text
View/download PDF

4. solarFLAG hare and hounds: estimation of p-mode frequencies from Sun-as-star helioseismology data

Author

Jimenez-Reyes, S. J., Chaplin, W. J., Garcia, R. A., Appourchaux, T., Baudin, F., Boumier, P., Elsworth, Y., Fletcher, S. T., Lazrek, M., Leibacher, J. W., Lochard, J., New, R., Regulo, C., Salabert, D., Toutain, T., Verner, G. A., and Wachter, R.

Subjects
Astrophysics
Abstract

We report on the results of the latest solarFLAG hare-and-hounds exercise, which was concerned with testing methods for extraction of frequencies of low-degree solar p modes from data collected by Sun-as-a-star observations. We have used the new solarFLAG simulator, which includes the effects of correlated mode excitation and correlations with background noise, to make artificial timeseries data that mimic Doppler velocity observations of the Sun as a star. The correlations give rise to asymmetry of mode peaks in the frequency power spectrum. Ten members of the group (the hounds) applied their ``peak bagging'' codes to a 3456-day dataset, and the estimated mode frequencies were returned to the hare (who was WJC) for comparison. Analysis of the results reveals a systematic bias in the estimated frequencies of modes above approximately 1.8 mHz. The bias is negative, meaning the estimated frequencies systematically underestimate the input frequencies. We identify two sources that are the dominant contributions to the frequency bias. Both sources involve failure to model accurately subtle aspects of the observed power spectral density in the part (window) of the frequency power spectrum that is being fitted. One source of bias arises from a failure to account for the power spectral density coming from all those modes whose frequencies lie outside the fitting windows. The other source arises from a failure to account for the power spectral density of the weak l=4 and 5 modes, which are often ignored in Sun-as-a-star analysis. The Sun-as-a-star peak-bagging codes need to allow for both sources, otherwise the frequencies are likely to be biased., Comment: 11 pages; accepted for publication in MNRAS

Published
2008
Full Text
View/download PDF

5. Searching for p-modes in MOST Procyon data: Another view

Author

Baudin, F., Appourchaux, T., Boumier, P., Kuschnig, R., Leibacher, J. W., and Matthews, J. M.

Subjects
Astrophysics
Abstract

Photometry of Procyon obtained by the MOST satellite in 2004 has been searched for p modes by several groups, with sometimes contradictory interpretations. We explore two possible factors that complicate the analysis and may lead to erroneous reports of p modes in these data. Two methods are used to illustrate the role of subtle instrumental effects in the photometry: time-frequency analysis, and a search for regularly spaced peaks in a Fourier spectrum based on the echelle diagramme approach. We find no convincing evidence of a p-mode signal in the MOST Procyon data. We can account for an apparent excess of power close to the p-mode frequency range and signs of structure in an echelle diagramme in terms of instrumental effects., Comment: Article accepted, to appear in A&A

Published
2007
Full Text
View/download PDF

6. Simu-LC : a Light-Curve simulator for CoRoT

Author

Baudin, F., Samadi, R., Appourchaux, T., and Michel, E.

Subjects
Astrophysics
Abstract

Simulating the data that a space instrument like COROT will provide might look presomptuous. Indeed, it is certainly, when comparing to previous comparable instruments like IPHIR or GOLF. These two examples show that the nominal behaviour of the instrument is not always reached, but this does not prevent this instrument to provide very interesting data. However, despite some technical problems, IPHIR and GOLF yielded a wealth of scientific results. Thus, what is the interest of simulating COROT data? How close to reality these simualtions will get? This might not be the most important fact as the preparation of these simulations will help us to prepare the analysis of real data and to be ready in case of unexpected technical behaviour of the instrument perturbating the data, or unexpected physical behaviour of the targets of the instrument. A consequence of that is that the simulation tool must include technical and physical aspects, making the task even more difficult. These aspects cover: photon noise, p modes excitation, granulation signal, stellar activity signal, orbital perturbations, stellar rotation... The software presented here is freely available at: http://www.lesia.obspm.fr/~corotswg/simulightcurve.html, Comment: Contribution to "The Corot book" published by ESA (SP 1306; Eds: M. Fridlund, A. Baglin, L. Conroy and J. Lochard). Due to a mistake, the references were not correctly compiled, this version corrects this mistake ; 5 pages ; 3 figures

Published
2007

7. The Corot Book: Chap. V.5/ Extraction of the photometric information : corrections

Author

Samadi, R., Fialho, F., Costa, J. E. S., Drummond, R., Da Silva, L. Pinheiro, Baudin, F., Boumier, P., and Jorda, L.

Subjects
Astrophysics
Abstract

We present here the set of corrections that will be applied to the raw data of the CoRoT mission. The aim is to correct the data for instrumental and environmental perturbations as well as to optimize the duty-cycle, in order to reach the expected performances of the mission. The main corrections are : the correction of the electromagnetic interferences, suppression of outliers, the background correction, the jitter correction and the correction of the integration time variations. We focus here on these corrections and emphasize their efficiency., Comment: Contribution to "The Corot book" published by ESA (SP 1306; Eds: M. Fridlund, A. Baglin, L. Conroy and J. Lochard). Due to a mistake, the published version is not the final version that should have been published. This version replaced the one published in ESA-SP 1306 ; 9 pages ; 16 figures

Published
2007

8. A closure model with plumes II. Application to the stochastic excitation of stellar p modes

Author

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

Subjects
Astrophysics
Abstract

Our goal is to improve the theoretical modelling of stochastic excitation of p modes by turbulent convection. With the help of the closure model with plume (CMP) developed in a companion paper, we refine the theoretical description of the excitation by the turbulent Reynolds stress term. The CMP is generalized for two-point correlation products so as to apply it to the formalism developed by Samadi & Goupil (2001). The excitation source terms are then computed with this improvement, and a comparison with solar data from the GOLF instrument is performed. The present model provides a significant improvement when comparing absolute values of theoretical ampplitudes with observational data. It gives rise to a frequency dependence of the power supplied to solar p modes, which agrees with GOLF observations. It is shown that the asymmetry of the turbulent convection zone (up- and downflows) plays a major role in the excitation processes. Despite an increase in the Reynolds stress term contribution due to our improved description, an additional source of excitation, identified as the entropy source term, is still necessary for reproducing the observational data. Theoretical excitation rates in the frequency range [2.5 mHz, 4 mHz] now are in agreement with the observational data from the GOLF instrument. However, at lower frequencies, it exhibits small discrepancies at the maximum level of a few per cent. Improvements are likely to come from a better physical description of the excitation by entropy fluctuations in the superadiabatic zone., Comment: 9 pages, accepted for publication in A&A

Published
2006
Full Text
View/download PDF

9. solarFLAG hare and hounds: on the extraction of rotational p-mode splittings from seismic, Sun-as-a-star data

Author

Chaplin, W. J., Appourchaux, T., Baudin, F., Boumier, P., Elsworth, Y., Fletcher, S. T., Fossat, E., Garcia, R. A., Isaak, G. R., Jimenez, A., Jimenez-Reyes, S. J., Lazrek, M., Leibacher, J. W., Lochard, J., New, R., Palle, P., Regulo, C., Salabert, D., Seghouani, N., Toutain, T., and Wachter, R.

Subjects
Astrophysics
Abstract

We report on results from the first solar Fitting at Low-Angular degree Group (solar FLAG) hare-and-hounds exercise. The group is concerned with the development of methods for extracting the parameters of low-l solar p mode data (`peak bagging'), collected by Sun-as-a-star observations. Accurate and precise estimation of the fundamental parameters of the p modes is a vital pre-requisite of all subsequent studies. Nine members of the FLAG (the `hounds') fitted an artificial 3456-d dataset. The dataset was made by the `hare' (WJC) to simulate full-disc Doppler velocity observations of the Sun. The rotational frequency splittings of the l=1, 2 and 3 modes were the first parameter estimates chosen for scrutiny. Significant differences were uncovered at l=2 and 3 between the fitted splittings of the hounds. Evidence is presented that suggests this unwanted bias had its origins in several effects. The most important came from the different way in which the hounds modeled the visibility ratio of the different rotationally split components. Our results suggest that accurate modelling of the ratios is vital to avoid the introduction of significant bias in the estimated splittings. This is of importance not only for studies of the Sun, but also of the solar analogues that will targets for asteroseismic campaigns.

Published
2006
Full Text
View/download PDF

10. Oscillation power spectra of the Sun and of Alpha Cen A: observations versus models

Author

Samadi, R., Goupil, M. J., Baudin, F., Georgobiani, D., Trampedach, R., Stein, R., and Nordlund, A.

Subjects
Astrophysics
Abstract

Hydrodynamical, 3D simulations of the outer layers of the Sun and Alpha Cen A are used to obtain constraints on the properties of turbulent convection in such stars. These constraints enable us to compute - on the base of a theoretical model of stochastic excitation - the rate P at which p modes are excited by turbulent convection in those two stars. Results are then compared with solar seismic observations and recent observations of Alpha Cen A. For the Sun, a good agreement between observations and computed P is obtained. For Alpha Cen A a large discrepancy is obtained which origin cannot be yet identified: it can either be caused by the present data quality which is not sufficient for our purpose or by the way the intrinsic amplitudes and the life-times of the modes are determined or finally attributed to our present modelling. Nevertheless, data with higher quality or/and more adapted data reductions will likely provide constraints on the p-mode excitation mechanism in Alpha Cen A., Comment: 4 pages, 4 figures, proceedings of the SOHO14/GONG 2004 Workshop "Helio- and Asteroseismology: Towards a Golden Future" from July 12-16 2004 at New Haven CT (USA)

Published
2004

11. Seismic diagnostics on stellar convection treatment from oscillation amplitudes of p-modes

Author

Samadi, R., Goupil, M. J., Lebreton, Y., Nordlund, A., and Baudin, F.

Subjects
Astrophysics
Abstract

The excitation rate P of solar p-modes is computed with a model of stochatic excitation which involves constraints on the averaged properties of the solar turbulence. These constraints are obtained from a 3D simulation. Resulting values for P are found ~9 times larger than when the calculation assumes properties of turbulent convection which are derived from an 1D solar model based on Gough (1977)'s formulation of the mixing-length theory (GMLT). This difference is mainly due to the assumed values for the mean anisotropy of the velocity field in each case.Calculations based on 3D constraints bring the P maximum closer to the observational one.We also compute P for several models of intermediate mass stars (1Mo < M < 2Mo). Differences in the values of P_max between models computed with the classical mixing-length theory and GMLT models are found large enough for main sequence stars to suggest that measurements of P in this mass range will be able to discriminate between different models of turbulent convection., Comment: 4 pages, 1 figure, proceedings of the conference "Asteroseismology Across the HR Diagram" held in Porto (Portugal) in July 2002, to be published by Kluwer as an issue of the Astrophysics and Space Science Journal

Published
2002

12. Modeling of two CoRoT solar analogues constrained by seismic and spectroscopic analysis.

Author

Castro, M, Baudin, F, Benomar, O, Samadi, R, Morel, T, Barban, C, do Nascimento, J D, Lebreton, Y, Boumier, P, Marques, J P, and da Costa, J S

Subjects
*STELLAR evolution, *EVOLUTIONARY models, *AGE of stars, *ASTROPHYSICS, *SEISMIC networks, *PHYSICS
Abstract

Solar analogues are important stars to study for understanding the properties of the Sun. Combined with seismic and spectroscopic analysis, evolutionary modelling becomes a powerful method to characterize stellar intrinsic parameters, such as mass, radius, metallicity and age. However, these characteristics, relevant for other aspects of astrophysics or exoplanetary system physics, for example, are difficult to obtain with high precision and/or accuracy. The goal of this study is to characterize the two solar analogues, HD 42618 and HD 43587, observed by CoRoT. In particular, we aim to infer their precise mass, radius and age, using evolutionary modelling constrained by spectroscopic, photometric and seismic analysis. These stars show evidence of being older than the Sun but with a relatively large lithium abundance. We present the seismic analysis of HD 42618, and the modelling of the two solar analogues, HD 42618 and HD 43587 using the cestam stellar evolution code. Models were computed to reproduce the spectroscopic (effective temperature and metallicity) and seismic (mode frequency) data, and the luminosity of the stars, based on Gaia parallaxes. We infer very similar values of mass and radius for both stars compared with the literature, within the uncertainties, and we reproduce correctly the seismic constraints. The modelling shows that HD 42618 is slightly less massive and older than the Sun, and that HD 43587 is more massive and older than the Sun, in agreement with previous results. The use of chemical clocks improves the reliability of our age estimates. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

13. OH and H2O maser variations in W33B

Author

Chiappini, C., Anders, F., Rodrigues, T., Miglio, A., Montalban, J., Mosser, B., Girardi, L., Valentini, M., Noels, A., Morel, T., Minchev, I., Steinmetz, M., Santiago, B., Schultheis, M., Martig, M., da Costa, L., Maia, M., Allende Prieto, C., de Assis Peralta, R., Hekker, S., Themessl, N., Kallinger, T., Garcia, R., Mathur, S., Baudin, F., Beers, T., Cunha, K., Harding, P., Holtzman, J., Majewski, S., Mészáros, Sz., Nidever, D., Pan, K., Schiavon, R., Shetrone, M., Schneider, D., Stassun, K., Colom, P., Lekht, E., Pashchenko, M., Rudnitskij, G., Leibniz-Institut für Astrophysik Potsdam (AIP), Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Département d'astrophysique, Géophysique et Océanographie (AGO), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Liverpool John Moores University (LJMU), Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), School of Physics and Astronomy, University of Birmingham [Birmingham], Institute for Astronomy [Vienna], University of Vienna [Vienna], Institut de Physique du Globe de Paris (IPG Paris), Space Science Institute [Boulder] (SSI), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Center for the Study of Cosmic Evolution (CSCE), Michigan State University [East Lansing], Michigan State University System-Michigan State University System, Department of Geography, Department of geography, Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris, Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
individual objects, 85A15, lines and bands -ISM, Astrophysics::High Energy Astrophysical Phenomena, Central object, FOS: Physical sciences, Astrophysics, 01 natural sciences, W33B, law.invention, Radio telescope, symbols.namesake, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Maser, masers -ISM, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, magnetic fields -ISM, Line (formation), [PHYS]Physics [physics], Physics, Zeeman effect, 010308 nuclear & particles physics, molecules -ISM, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Magnetic field, Wavelength, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), symbols, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Excitation
Abstract

The active star-forming region W33B is a source of OH and H2O maser emission located in distinct zones around the central object. The aim was to obtain the complete Stokes pattern of polarised OH maser emission, to trace its variability and to investigate flares and long-term variability of the H2O maser and evolution of individual emission features. Observations in the OH lines at a wavelength of 18 cm were carried out on the Nan\c{c}ay radio telescope (France) at a number of epochs in 2008--2014; H2O line observations (long-term monitoring) at a wavelength of 1.35 cm were performed on the 22-metre radio telescope of the Pushchino Radio Astronomy Observatory (Russia) between 1981 and 2014. We have observed strong variability of the emission features in the main 1665- and 1667-MHz OH lines as well as in the 1612-MHz satellite line. Zeeman splitting has been detected in the 1665-MHz OH line at 62 km/s and in the 1667-MHz line at 62 and 64 km/s. The magnetic field intensity was estimated to be from 2 to 3 mG. The H2O emission features form filaments, chains with radial-velocity gradients, or more complicated structures including large-scale ones. Long-term observations of the hydroxyl maser in the W33B region have revealed narrowband polarised emission in the 1612-MHz line with a double-peak profile characteristic of Type IIb circumstellar masers. The 30-year monitoring of the water-vapour maser in W33B showed several strong flares of the H2O line. The observed radial-velocity drift of the H2O emission features suggests propagation of an excitation wave in the masering medium with a gradient of radial velocities. In OH and H2O masers some turbulent motions of material are inferred., Comment: 18 pages, 12 figures

Published
2015

14. Red Giants observed with CoRoT.

Author

Hekker, S., De Ridded, J., Baudin, F., Barban, C., Carrier, F., Hatzes, A. P., Kallinger, T., and Weiss, W. W.

Subjects
STARS, ASTROPHYSICS, RED giants, STELLAR oscillations, ASTRONOMICAL photometry, SEISMOLOGY
Abstract

Observations of red (G-K)-giant stars with the CoRoT satellite provide unprecedented information on the stochastically excited oscillations in these stars. The long time series of nearly uninterrupted high-cadence and high-precision photometry revealed the presence of non-radial modes with long lifetimes, which opens the possibility to perform asteroseismology on these stars. Also, the large number of red giants, for which solar-like oscillations are now observed, allows for a more statistical investigation of the characteristics of solar-like oscillations in red giants. [ABSTRACT FROM AUTHOR]

Published
2009
Full Text
View/download PDF

15. Gravito-inertial and pressure modes detected in the B3IV CoRoT target HD43317.

Author

Pápics, P. I., Briquet, M., Baglin, A., Poretti, E., Aerts, C., Degroote, P., Tkachenko, A., Morel, T., Zima, W., Niemczura, E., Rainer, M., Hareter, M., Baudin, F., Catala, C., Michel, E., Samadi, R., and Auvergne, M.

Subjects
STARS, SPECTRUM analysis, STELLAR activity, ASTROPHYSICS, TIME series analysis
Abstract

Context. OB stars are important building blocks of the Universe, but we have only a limited sample of them well understood enough from an asteroseismological point of view to provide feedback on the current evolutionary models. Our study adds one special case to this sample, with more observational constraints than for most of these stars. Aims. Our goal is to analyse and interpret the pulsational behaviour of the B3?IV star HD?43317 using the CoRoT light curve along with the ground-based spectroscopy gathered by the HARPS instrument. This way we continue our efforts to map the β?Cep and SPB instability strips. Methods. We used different techniques to reveal the abundances and fundamental stellar parameters from the newly-obtained high-resolution spectra. We used various time-series analysis tools to explore the nature of variations present in the light curve. We calculated the moments and used the pixel-by-pixel method to look for line profile variations in the high-resolution spectra. Results. We find that HD?43317 is a single fast rotator (vrot ≈ 50% ? vcrit) and hybrid SPB/β?Cep-type pulsator with Solar metal abundances. We interpret the variations in photometry and spectroscopy as a result of rotational modulation connected to surface inhomogeneities, combined with the presence of both g and p mode pulsations. We detect a series of ten consecutive frequencies with an almost constant period spacing of 6339?s as well as a second shorter sequence consisting of seven frequencies with a spacing of 6380?s. The dominant frequencies fall in the regime of gravito-inertial modes. [ABSTRACT FROM AUTHOR]

Published
2012
Full Text
View/download PDF

16. Pulsation spectrum of δ Scuti stars: the binary HD 50870 as seen with CoRoT and HARPS.

Author

Mantegazza, L., Poretti, E., Michel, E., Rainer, M., Baudin, F., García Hernández, A., Semaan, T., Alvarez, M., Amado, P. J., Garrido, R., Mathias, P., Moya, A., Suárez, J. C., Auvergne, M., Baglin, A., Catala, C., and Samadi, R.

Subjects
STELLAR oscillations, ASTRONOMICAL observations, HIGH resolution spectroscopy, PHOTOMETRY, ASTROPHYSICS
Abstract

Aims. We present the results obtained with the CoRoT satellite for HD 50870, a δ Sct star which was observed for 114.4 d. The aim of these observations was to evaluate the results obtained for HD 50844, the first S Sct star monitored with CoRoT, on a longer time baseline. Methods. The 307,570 CoRoT datapoints were analysed with different techniques. The photometric observations were complemented over 15 nights of high-resolution spectroscopy with HARPS on a baseline of 25 d. These spectra were analysed to study the line profile variations and to derive the stellar physical parameters. Some uvby photometric observations were also obtained to better characterize the pulsation modes. Results. HD 50870 proved to be a low-amplitude, long-period spectroscopic binary system seen almost pole-on (i ≃ 21°). The brighter component, which also has the higher rotational velocity (v sin i = 37.5 km s-1), is a δ Sct-type variable with a full light amplitude variation of about 0.04 mag. There is a dominant axisymmetric mode (17.16 d-1). Moreover, there are two groups of frequencies (about 19) in the intervals 6-9 and 13-18 d-1, with amplitudes ranging from a few mmag to 0.3 mmag. After the detection of about 250 terms (corresponding to an amplitude of about 0.045 mmag) a flat plateau appears in the power spectrum in the low-frequency region up to about 35 d-1 We were able to detect this plateau only thanks to the short cadence sampling of the CoRoT measurements (32 s). The density distribution vs. frequency of the detected frequencies seems to rule out the possibility that this plateau is the result of a process with a continuum power spectrum. The spacings of the strongest modes suggest a quasi-periodic pattern. We failed to find a satisfactory seismic model that simultaneously matches the frequency range, the position in the HR diagram, and the quasi-periodic pattern interpreted as a large separation. Nineteen modes were detected spectroscopically from the line profile variations and associated to the photometric ones. Tentative l, m values have been attributed to the modes detected spectroscopically. Prograde as well as retrograde modes are present with C values up to 9. There are no traces of variability induced by solar-like oscillations. [ABSTRACT FROM AUTHOR]

Published
2012
Full Text
View/download PDF

17. Acoustic spectrum fitting for a large set of solar-like pulsators.

Author

Benomar, O., Baudin, F., Chaplin, W. J., Elsworth, Y., and Appourchaux, T.

Subjects
*ACOUSTIC spectroscopy, *STELLAR structure, *SEISMOLOGY, *SOLAR radiation, *ASTROPHYSICS, *DATA analysis, *BAYESIAN analysis
Abstract

ABSTRACT Asteroseismology provides the means both to constrain the global properties and to probe the internal structures of stars. Asteroseismic data are now available on large numbers of solar-type stars, thanks in particular to the CoRoT and Kepler space missions, and automated data-analysis pipelines are needed to provide efficient and timely results. Here, we present an automated algorithm that is able to extract mode parameters under low signal-to-noise ratio conditions. We use a Bayesian framework to ensure the robustness of the algorithm. We discuss the efficiency of the method and test it using Variability of Solar Irradiance and Gravity Oscillations (VIRGO) Sun-as-a-star photometry data and the artificial Astero Fitting at Low Angular degree Group (asteroFLAG) Kepler ensemble. Analysis of the VIRGO data shows that it is possible to track variations of the individual mode parameters (frequency, height, width) through the solar cycle, using short time series (30 days). The present analysis also revealed a modulation of the degree l = 2 relative height through the solar cycle. Applied on asteroFLAG data, we show that the pipeline extracts accurately the central frequency and the large separation. It is also able to identify the degree of the modes in 78 per cent of stars. [ABSTRACT FROM AUTHOR]

Published
2012
Full Text
View/download PDF

18. Modelling a high-mass red giant observed by CoRoT.

Author

Baudin, F., Barban, C., Goupil, M. J., Samadi, R., Lebreton, Y., Bruntt, H., Morel, T., Lefèvre, L., Michel, E., Mosser, B., Carrier, F., De Ridder, J., Hatzes, A., Hekker, S., Kallinger, T., Auvergne, M., Baglin, A., and Catala, C.

Subjects
*RED giants, *PHOTOMETERS, *NOBLE gases, *RADIOACTIVITY, *ASTROPHYSICS
Abstract

Context. The advent of space-borne photometers such as CoRoT and Kepler has opened up new fields in asteroseismology. This is especially true for red giants as only a few of these stars were known to oscillate with small amplitude, solar-like oscillations before the launch of CoRoT. Aims. The G6 giant HR2582 (HD50890) was observed by CoRoT for approximately 55 days. We present here the analysis of its light curve and the characterisation of the star using different observables, such as its location in the Hertzsprung-Russell diagram and seismic observables. Methods. Mode frequencies are extracted from the observed Fourier spectrum of the light curve. Numerical stellar models are then computed to determine the characteristics of the star (mass, age, etc.) from the comparison with observational constraints. Results. We provide evidence for the presence of solar-like oscillations at low frequency, between 10 and 20 μHz, with a regular spacing of (1.7±0.1) μHz between consecutive radial orders. Only radial modes are clearly visible. From the models compatible with the observational constraints used here,We find that HR2582 (HD50890) is a massive star with a mass in the range (3-5 M☉), clearly above the red clump. It oscillates with rather low radial order (n = 5-12) modes. Its evolutionary stage cannot be determined with precision: the star could be on the ascending red giant branch (hydrogen shell burning) with an age of approximately 155 Myr or in a later phase (helium burning). In order to obtain a reasonable helium amount, the metallicity of the star must be quite subsolar. Our best models are obtained with a mixing length significantly smaller than that obtained for the Sun with the same physical description (except overshoot). The amount of core overshoot during the main-sequence phase is found to be mild, of the order of 0.1 Hp. Conclusions. HR 2582 (HD50890) is an interesting case as only a few massive stars can be observed due to their rapid evolution compared to less massive red giants. HR2582 (HD50890) is also one of the few cases that can be used to validate the scaling relations for massive red giants stars and its sensitivity to the physics of the star. [ABSTRACT FROM AUTHOR]

Published
2012
Full Text
View/download PDF

19. The quest for the solar g modes.

Author

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., and Toutain, T.

Subjects
SOLAR gravity, EIGENFUNCTIONS, SUN, HELIOSEISMOLOGY, ASTRONOMY, ASTROPHYSICS
Abstract

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. [ABSTRACT FROM AUTHOR]

Published
2010
Full Text
View/download PDF

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

Author

A. Miglio, C. Chiappini, B. Mosser, G. R. Davies, K. Freeman, L. Girardi, P. Jofré, D. Kawata, B. M. Rendle, M. Valentini, L. Casagrande, W. J. Chaplin, G. Gilmore, K. Hawkins, B. Holl, T. Appourchaux, K. Belkacem, D. Bossini, K. Brogaard, M.‐J. Goupil, J. Montalbán, A. Noels, F. Anders, T. Rodrigues, G. Piotto, D. Pollacco, H. Rauer, C. Allende Prieto, P. P. Avelino, C. Babusiaux, C. Barban, B. Barbuy, S. Basu, F. Baudin, O. Benomar, O. Bienaymé, J. Binney, J. Bland‐Hawthorn, A. Bressan, C. Cacciari, T. L. Campante, S. Cassisi, J. Christensen‐Dalsgaard, F. Combes, O. Creevey, M. S. Cunha, R. S. Jong, P. Laverny, S. Degl'Innocenti, S. Deheuvels, É. Depagne, J. Ridder, P. Di Matteo, M. P. Di Mauro, M.‐A. Dupret, P. Eggenberger, Y. Elsworth, B. Famaey, S. Feltzing, R. A. García, O. Gerhard, B. K. Gibson, L. Gizon, M. Haywood, R. Handberg, U. Heiter, S. Hekker, D. Huber, R. Ibata, D. Katz, S. D. Kawaler, H. Kjeldsen, D. W. Kurtz, N. Lagarde, Y. Lebreton, M. N. Lund, S. R. Majewski, P. Marigo, M. Martig, S. Mathur, I. Minchev, T. Morel, S. Ortolani, M. H. Pinsonneault, B. Plez, P. G. Prada Moroni, D. Pricopi, A. Recio‐Blanco, C. Reylé, A. Robin, I. W. Roxburgh, M. Salaris, B. X. Santiago, R. Schiavon, A. Serenelli, S. Sharma, V. Silva Aguirre, C. Soubiran, M. Steinmetz, D. Stello, K. G. Strassmeier, P. Ventura, R. Ventura, N. A. Walton, C. C. Worley, Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Arizona State University [Tempe] (ASU), Leibniz-Institut für Astrophysik Potsdam (AIP), Department of Physics and Astronomy [Aarhus], Aarhus University [Aarhus], School of Physics and Astronomy [Birmingham], University of Birmingham [Birmingham], Heckscher-Klinikum, Danish AsteroSeismology Centre (DASC), Universidade Federal de São Paulo (UNIFESP), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Department of Astronomy [New Haven], Yale University [New Haven], Evolution et Modélisation des Bassins Sédimentaires (EMBS), Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Department of Biomedical, Metabolic and Neural Sciences [Modena], Chaire Galaxies et cosmologie, Collège de France (CdF (institution)), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universidade de Aveiro, Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Las Cumbres Observatory (LCO), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Université de Strasbourg (UNISTRA), Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universitat de Girona (UdG), Max-Planck-Institut für Extraterrestrische Physik (MPE), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, SETI Institute, University of Illinois at Urbana Champaign (UIUC), University of Illinois at Urbana-Champaign [Urbana], University of Illinois System-University of Illinois System, Universidade Federal de Santa Catarina = Federal University of Santa Catarina [Florianópolis] (UFSC), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Space Science Institute [Boulder] (SSI), Department of Astronomy (Ohio State University), Ohio State University [Columbus] (OSU), Laboratoire Univers et Particules de Montpellier (LUPM), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Astrophysical Research Institute [Liverpool], Liverpool John Moore University (ljmu), Institute of Space Sciences [Barcelona] (ICE-CSIC), Spanish National Research Council [Madrid] (CSIC), Sydney Institute for Astronomy (SIfA), The University of Sydney, M2A 2017, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Leibniz Institute for Astrophysics Potsdam (AIP), Symbiose Marine (SM), Evolution Paris Seine, Université des Antilles et de la Guyane (UAG)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles et de la Guyane (UAG)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), DNRF106, The Danish National Research Foundation, Centre National d’Etudes Spatiales, PRIN INAF 2014 - CRA 1.05.01.94.05, Science and Technology Facilities Council, Programme National Cosmologie et Galaxies (CNRS/INSU, France), IF/00894/2012/, Federación Española de Enfermedades Raras, CNES Fellowship, 615604, ERC Consolidator (STARKEY), Federaal Wetenschapsbeleid, ESP2015-66134-R, Ministerio de Economía y Competitividad, European Commission's Seventh Framework Programme, Swedish National Space Board, European Commission, DLR, FT1400147, Australian Research Council, NNX16AI09G, National Aeronautics and Space Administration, European Cooperation in Science and Technology, CH1188/2-1, DFG, CA16117, ChETEC COST Action, 10118, Villum Fonden, European Union FP7 program, 320360, ERC, UID/FIS/04434/2013, FCT, G1502, NYUAD Institute, Programme National de Physique Stellaire (PNPS), ITA, USA, GBR, FRA, DEU, ESP, Federal University of Sao Paulo (Unifesp), Université Paris-Saclay, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Collège de France - Chaire Galaxies et cosmologie, Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Genève = University of Geneva (UNIGE), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, University of Illinois System, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université des Antilles et de la Guyane (UAG)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles et de la Guyane (UAG)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), Miglio A., Chiappini C., Mosser B., Davies G.R., Freeman K., Girardi L., Jofre P., Kawata D., Rendle B.M., Valentini M., Casagrande L., Chaplin W.J., Gilmore G., Hawkins K., Holl B., Appourchaux T., Belkacem K., Bossini D., Brogaard K., Goupil M.-J., Montalban J., Noels A., Anders F., Rodrigues T., Piotto G., Pollacco D., Rauer H., Prieto C.A., Avelino P.P., Babusiaux C., Barban C., Barbuy B., Basu S., Baudin F., Benomar O., Bienayme O., Binney J., Bland-Hawthorn J., Bressan A., Cacciari C., Campante T.L., Cassisi S., Christensen-Dalsgaard J., Combes F., Creevey O., Cunha M.S., Jong R.S., Laverny P., Degl'Innocenti S., Deheuvels S., Depagne E., Ridder J., Matteo P.D., Mauro M.P.D., Dupret M.-A., Eggenberger P., Elsworth Y., Famaey B., Feltzing S., Garcia R.A., Gerhard O., Gibson B.K., Gizon L., Haywood M., Handberg R., Heiter U., Hekker S., Huber D., Ibata R., Katz D., Kawaler S.D., Kjeldsen H., Kurtz D.W., Lagarde N., Lebreton Y., Lund M.N., Majewski S.R., Marigo P., Martig M., Mathur S., Minchev I., Morel T., Ortolani S., Pinsonneault M.H., Plez B., Moroni P.G.P., Pricopi D., Recio-Blanco A., Reyle C., Robin A., Roxburgh I.W., Salaris M., Santiago B.X., Schiavon R., Serenelli A., Sharma S., Aguirre V.S., Soubiran C., Steinmetz M., Stello D., Strassmeier K.G., Ventura P., Ventura R., Walton N.A., Worley C.C., Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Université Nice Sophia Antipolis (... - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles et de la Guyane (UAG)-Université Pierre et Marie Curie - Paris 6 (UPMC)

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

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

Published
2017

Catalog

Books, media, physical & digital resources
See catalog results