Author: "Noels, A." / Topic: stars - Searchworks@Jio Institute Digital Library Search Results

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119 results on '"Noels, A."'

1. Chronologically dating the early assembly of the Milky Way

Author: Jason W. Ferguson, J. Ted Mackereth, B. M. Rendle, Josefina Montalbán, Fiorenzo Vincenzo, Emma Willett, Guy R. Davies, M. Vrard, Cristina Chiappini, Saniya Khan, Richard Scuflaire, Andrea Miglio, Arlette Noels, B. Mosser, Martin Bo Nielsen, William J. Chaplin, Oliver J. Hall, Walter E. van Rossem, Gaël Buldgen, Montalban J., Mackereth J.T., Miglio A., Vincenzo F., Chiappini C., Buldgen G., Mosser B., Noels A., Scuflaire R., Vrard M., Willett E., Davies G.R., Hall O.J., Bo Nielsen M., Khan S., Rendle B.M., van Rossem W.E., Ferguson J.W., and Chaplin W.J.
Subjects: 010504 meteorology & atmospheric sciences, Milky Way, CHEMICAL EVOLUTION, STELLAR POPULATIONS, RED GIANTS, GAIA, ASTEROSEISMOLOGY, KINEMATICS, AGES, HALO, OSCILLATIONS, ABUNDANCES, Population, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Compact star, 01 natural sciences, 0103 physical sciences, Thick disk, Satellite galaxy, Astrophysics::Solar and Stellar Astrophysics, education, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, education.field_of_study, Astronomy, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Accretion (astrophysics), Stars, Astrophysics - Solar and Stellar Astrophysics, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, Geology
Abstract: The standard cosmological model ($\Lambda$-CDM) predicts that galaxies are built through hierarchical assembly on cosmological timescales$^{1,2}$. The Milky Way, like other disc galaxies, underwent violent mergers and accretion of small satellite galaxies in its early history. Thanks to Gaia-DR2$^3$ and spectroscopic surveys$^4$, the stellar remnants of such mergers have been identified$^{5-7}$. The chronological dating of such events is crucial to uncover the formation and evolution of the Galaxy at high redshift, but it has so far been challenging owing to difficulties in obtaining precise ages for these oldest stars. Here we combine asteroseismology -- the study of stellar oscillations -- with kinematics and chemical abundances, to estimate precise stellar ages ($\sim$ 11%) for a sample of stars observed by the $\mathit{Kepler}$ space mission$^8$. Crucially, this sample includes not only some of the oldest stars that were formed inside the Galaxy, but also stars formed externally and subsequently accreted onto the Milky Way. Leveraging this resolution in age, we provide compelling evidence in favour of models in which the Galaxy had already formed a substantial population of its stars (which now reside mainly in its thick disc) before the in-fall of the satellite galaxy Gaia-Enceladus/Sausage$^{5,6}$ around 10 billions years ago, Comment: Updated with the final version accepted for publication as a Letter in Nature Astronomy (29 pages, 10 figures, 2 tables, including main article and methods section). Improved presentation of results, which have not changed from the previous version
Published: 2021

2. Asteroseismology of HD 129929: Core Overshooting and Nonrigid Rotation

Author: Aerts, C., Thoul, A., Daszyńska, J., Scuflaire, R., Waelkens, C., Dupret, M. A., Niemczura, E., and Noels, A.
Published: 2003

3. On the impact of the structural surface effect on global stellar properties and asteroseismic analyses

Author: Richard Scuflaire, George C. Angelou, Andrea Miglio, Achim Weiss, Arlette Noels, Jakob Rørsted Mosumgaard, Victor Silva Aguirre, Andreas Christ Sølvsten Jørgensen, Josefina Montalbán, Jorgensen A.C.S., Montalban J., Angelou G.C., Miglio A., Weiss A., Scuflaire R., Noels A., Mosumgaard J.R., and Aguirre V.S.
Subjects: Monte Carlo method, statistical [methods], FOS: Physical sciences, Stratification (water), asteroseismology, stars: interiors, 01 natural sciences, Asteroseismology, stars: atmosphere, Mixing length model, 0103 physical sciences, Radiative transfer, Astrophysics::Solar and Stellar Astrophysics, Stellar structure, Boundary value problem, Statistical physics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, atmospheres [stars], interiors [stars], methods: statistical, 010308 nuclear & particles physics, Astronomy and Astrophysics, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics
Abstract: In a series of papers, we have recently demonstrated that it is possible to construct stellar structure models that robustly mimic the stratification of multi-dimensional radiative magneto-hydrodynamic simulations at every time-step of the computed evolution. The resulting models offer a more realistic depiction of the near-surface layers of stars with convective envelopes than parameterizations, such as mixing length theory, do. In this paper, we explore how this model improvement impacts on seismic and non-seismic properties of stellar models across the Hertzsprung-Russell diagram. We show that the improved description of the outer boundary layers alters the predicted global stellar properties at different evolutionary stages. In a hare and hound exercise, we show that this plays a key role for asteroseismic analyses, as it, for instance, often shifts the inferred stellar age estimates by more than 10 per cent. Improper boundary conditions may thus introduce systematic errors that exceed the required accuracy of the PLATO space mission. Moreover, we discuss different approximations for how to compute stellar oscillation frequencies. We demonstrate that the so-called gas $\Gamma_1$ approximation performs reasonably well for all main-sequence stars. Using a Monte Carlo approach, we show that the model frequencies of our hybrid solar models are consistent with observations within the uncertainties of the global solar parameters when using the so-called reduced $\Gamma_1$ approximation., Comment: Submitted to MNRAS
Published: 2021

4. Age dissection of the Milky Way discs: Red giants in the Kepler field

Author: Andrea Miglio, Diego Bossini, Saniya Khan, Guy R. Davies, Luca Casagrande, Cristina Chiappini, Thaíse S. Rodrigues, Karsten Brogaard, Arlette Noels, B. Mosser, Rob Izzard, William J. Chaplin, L. Girardi, J. T. Mackereth, Ilya Mandel, Fiorenzo Vincenzo, Josefina Montalbán, Marica Valentini, Daisuke Kawata, Miglio A., Chiappini C., MacKereth J.T., Davies G.R., Brogaard K., Casagrande L., Chaplin W.J., Girardi L., Kawata D., Khan S., Izzard R., Montalban J., Mosser B., Vincenzo F., Bossini D., Noels A., Rodrigues T., Valentini M., and Mandel I.
Subjects: Stellar mass, Metallicity, Mass-loss [Stars], Stars: Mass-loss, FOS: Physical sciences, Stellar content [Galaxy], Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galaxy: Structure, Late-type [Stars], Galaxy: Evolution, Structure [Galaxy], 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Stars: Late-type, 010303 astronomy & astrophysics, Red clump, Stellar evolution, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, Star formation, Asteroseismology, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Galaxy: Stellar content, Stars, Evolution [Galaxy], Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, Open cluster
Abstract: [Abridged] Ensemble studies of red-giant stars with exquisite asteroseismic, spectroscopic, and astrometric constraints offer a novel opportunity to recast and address long-standing questions concerning the evolution of stars and of the Galaxy. Here, we infer masses and ages for nearly 5400 giants with available Kepler light curves and APOGEE spectra, and discuss some of the systematics that may affect the accuracy of the inferred stellar properties. First, we look at age-chemical-abundances relations. We find a dearth of young, metal-rich stars, and the existence of a significant population of old (8-9 Gyr), low-[$\alpha$/Fe], super-solar metallicity stars, reminiscent of the age and metallicity of the well-studied open cluster NGC6791. The age-chemo-kinematic properties of these stars indicate that efficient radial migration happens in the thin disk. We find that ages and masses of the nearly 400 $\alpha$-element-rich red-giant-branch (RGB) stars in our sample are compatible with those of an old (~11 Gyr), nearly coeval, chemical-thick disk population. Using a statistical model, we show that 95% of the population was born within ~1.5 Gyr. Moreover, we find a difference in the vertical velocity dispersion between low- and high-[$\alpha$/Fe] populations, confirming their different chemo-dynamical histories. We then exploit the almost coeval $\alpha$-rich population to gain insight into processes that may have altered the mass of a star along its evolution, which are key to improve the mapping of the observed stellar mass to age. We find evidence for a mean integrated RGB mass loss = 0.10 $\pm$ 0.02 Msun and that the occurrence of massive (M $\gtrsim$ 1.1 Msun) $\alpha$-rich stars is of the order of 5% on the RGB, and significantly higher in the RC, supporting the scenario in which most of these stars had undergone interaction with a companion., Comment: accepted for publication in A&A, 26 pages, 24 figures, catalogue available via cds
Published: 2021

5. Solar-like Oscillations in a Massive Star

Author: Belkacem, Kévin, Samadi, Réza, Goupil, Marie-Jo, Lefèvre, Laure, Baudin, Fréderic, Deheuvels, Sébastien, Dupret, Marc-Antoine, Appourchaux, Thierry, Scuflaire, Richard, Auvergne, Michel, Catala, Claude, Michel, Eric, Miglio, Andrea, Montalban, Josefina, Thoul, Anne, Talon, Suzanne, Baglin, Annie, and Noels, Arlette
Published: 2009
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6. CoRoT Measures Solar-like Oscillations and Granulation in Stars Hotter than the Sun

Author: Michel, Eric, Baglin, Annie, Auvergne, Michel, Catala, Claude, Samadi, Reza, Baudin, Frédéric, Appourchaux, Thierry, Barban, Caroline, Weiss, Werner W., Berthomieu, Gabrielle, Bournier, 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, de Medeiros, José Renan, Ribas, Ignasi, Rieutord, Michel L., Cortés, Teodoro Roca, and Zwintz, Konstanze
Published: 2008
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7. HAYDN - High-precision AsteroseismologY of DeNse stellar fields

Author: Giampaolo Piotto, Igor Soszyński, Marc-Antoine Dupret, Frank Grundahl, Valerio Nascimbeni, Demetrio Magrin, Andrea Miglio, Cristina Chiappini, Silvia Toonen, Arlette Noels, Gaël Buldgen, Eline Tolstoy, Eric Michel, William Chantereau, Nadège Lagarde, Amaury H. M. J. Triaud, Bill Chaplin, Karsten Brogaard, Angela Bragaglia, Ted Mackereth, Mark Gieles, Léo Girardi, Georges Meynet, Rob Izzard, Roberto Ragazzoni, Patrick Eggenberger, Benoit Mosser, Nate Bastian, Daisuke Kawata, Josefina Montalbán, Christoffer Karoff, Fiorenzo Vincenzo, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), European Commission, International Space Science Institute, Science and Technology Facilities Council (UK), Swiss National Science Foundation, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Miglio A., Girardi L., Grundahl F., Mosser B., Bastian N., Bragaglia A., Brogaard K., Buldgen G., Chantereau W., Chaplin W., Chiappini C., Dupret M.-A., Eggenberger P., Gieles M., Izzard R., Kawata D., Karoff C., Lagarde N., Mackereth T., Magrin D., Meynet G., Michel E., Montalban J., Nascimbeni V., Noels A., Piotto G., Ragazzoni R., Soszynski I., Tolstoy E., Toonen S., Triaud A., Vincenzo F., and Low Energy Astrophysics (API, FNWI)
Subjects: bulge [Galaxy], Astrophysics::Cosmology and Extragalactic Astrophysics, Globular cluster, low-mass, gGlobular clusters, galaxy: bulge, galaxies: dwarf, asteroseismology [stars], 7. Clean energy, 01 natural sciences, Asteroseismology, Galaxy: bulge, Bulge, low-mass [Stars], Globular clusters, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Stars: low-mass, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, dwarf, Physics, 010308 nuclear & particles physics, Galaxies: dwarf, bulge, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Galaxies, Stars, dwarf [Galaxies], Galaxy, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Miglio, A., et al., In the last decade, the Kepler and CoRoT space-photometry missions have demonstrated the potential of asteroseismology as a novel, versatile and powerful tool to perform exquisite tests of stellar physics, and to enable precise and accurate characterisations of stellar properties, with impact on both exoplanetary and Galactic astrophysics. Based on our improved understanding of the strengths and limitations of such a tool, we argue for a new small/medium space mission dedicated to gathering high-precision, high-cadence, long photometric series in dense stellar fields. Such a mission will lead to breakthroughs in stellar astrophysics, especially in the metal poor regime, will elucidate the evolution and formation of open and globular clusters, and aid our understanding of the assembly history and chemodynamics of the Milky Way’s bulge and a few nearby dwarf galaxies., AM, JM and FV acknowledge support from the European Research Council Consolidator Grant funding scheme (project ASTEROCHRONOMETRY, G.A. n. 772293, http://www.asterochronometry.eu). AM, BM and LG are grateful to the International Space Science Institute (ISSI) for support provided to the asteroSTEP ISSI International Team. AM and WJC acknowledge the support of the UK Science and Technology Facilities Council (STFC). GB is sponsored by the Swiss National Science Foundation (project number 200020 − 172505). WC acknowledges funding from the Swiss National Science Foundation under grant P400P2_183846. We thank G. R. Davies for providing the power spectra used in Fig. 1. N.L. acknowledges financial support from “Programme National de Physique Stellaire” (PNPS) of CNRS/INSU, France. CC acknowledges partial support from DFG Grant CH1188/2-1 and from the ChETEC COST Action (CA16117), supported by COST (European Cooperation in Science and Technology).
Published: 2019

8. Thorough characterisation of the 16 Cygni system Part I: Forward seismic modelling with WhoSGlAd

Author: C. Pezzotti, M. Farnir, Arlette Noels, Patrick Eggenberger, M. A. Dupret, C. Pinçon, Sébastien Salmon, and Gaël Buldgen
Subjects: Physics, Minimisation (psychology), FOS: Physical sciences, Binary number, Astronomy and Astrophysics, Context (language use), Astrophysics, 01 natural sciences, Kepler, Asteroseismology, Set (abstract data type), Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Stellar structure, 14. Life underwater, Astrophysics::Earth and Planetary Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, Algorithm, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics
Abstract: Context: Being part of the brightest solar-like stars, and close solar analogues, the 16 Cygni system is of great interest to the scientific community and may provide insight into the past and future evolution of our Sun. It has been observed thoroughly by the Kepler satellite, which provided us with data of an unprecedented quality. Aims: This paper is the first of a series aiming to extensively characterise the system. We test several choices of micro- and macro-physics to highlight their effects on optimal stellar parameters and provide realistic stellar parameter ranges. Methods: We used a recently developed method, WhoSGlAd, that takes the utmost advantage of the whole oscillation spectrum of solar-like stars by simultaneously adjusting the acoustic glitches and the smoothly varying trend. For each choice of input physics, we computed models which account, at best, for a set of seismic indicators that are representative of the stellar structure and are as uncorrelated as possible. The search for optimal models was carried out through a Levenberg-Marquardt minimisation. First, we found individual optimal models for both stars. We then selected the best candidates to fit both stars while imposing a common age and composition. Results: We computed realistic ranges of stellar parameters for individual stars. We also provide two models of the system regarded as a whole. We were not able to build binary models with the whole set of choices of input physics considered for individual stars as our constraints seem too stringent. We may need to include additional parameters to the optimal model search or invoke non-standard physical processes., 25 pages, Accepted for publication in Astronomy and Astrophysics
Published: 2020

9. CLÉS, Code Liégeois d’Évolution Stellaire

Author: Scuflaire, R., Théado, S., Montalbán, J., Miglio, A., Bourge, P.-O., Godart, M., Thoul, A., and Noels, A.
Published: 2008
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10. The Liège Oscillation code

Author: Scuflaire, R., Montalbán, J., Théado, S., Bourge, P.-O., Miglio, A., Godart, M., Thoul, A., and Noels, A.
Published: 2008
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11. Apsidal motion in the massive binary HD 152248 -- Constraining the internal structure of the stars

Author: Marc-Antoine Dupret, Gregor Rauw, Sophie Rosu, Alfred F. Noels, M. Farnir, and Sylvia Ekström
Subjects: Physics, Orbital plane, Turbulent diffusion, Metallicity, Stellar rotation, Apsidal precession, FOS: Physical sciences, Astronomy and Astrophysics, Context (language use), Astrophysics, 01 natural sciences, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, Stellar evolution, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: Apsidal motion in massive eccentric binaries offers precious information about the internal structure of the stars. This is especially true for twin binaries consisting of two nearly identical stars. We make use of the tidally induced apsidal motion in the twin binary HD152248 to infer constraints on the internal structure of the O7.5 III-II stars composing this system. We build stellar evolution models with the code Cl\'es assuming different prescriptions for the internal mixing occurring inside the stars. We identify the models that best reproduce the observationally determined present-day properties of the components of HD152248, as well as their $k_2$, and the apsidal motion rate of the system. We analyse the impact of some poorly constrained input parameters, including overshooting, turbulent diffusion, and metallicity. We further build 'single' and 'binary' GENEC models that account for stellar rotation to investigate the impacts of binarity and rotation. We discuss some effects that could bias our interpretation of the apsidal motion in terms of the internal structure constant. Reproducing the observed $k_2$ value and rate of apsidal motion simultaneously with the other stellar parameters requires a significant amount of internal mixing or enhanced mass-loss. The results suggest that a single-star evolution model is sufficient to describe the physics inside this binary system. Qualitatively, the high turbulent diffusion required to reproduce the observations could be partly attributed to stellar rotation. Higher-order terms in the apsidal motion are negligible. Only a very severe misalignment of the rotation axes could significantly impact the rate of apsidal motion, but such a high misalignment is highly unlikely in such a binary system. We infer an age estimate of $5.15\pm0.13$ Myr for the binary and initial masses of $32.8\pm0.6$ M$_\odot$ for both stars., Comment: 16 pages, A&A accepted
Published: 2020
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12. Ages for large samples of stars - caveats and uncertainties

Author: Arlette Noels-Grötsch
Subjects: Time line, Stars, Space and Planetary Science, Red giant, Computer science, Stellar physics, Galaxy formation and evolution, Astronomy, Astronomy and Astrophysics, Context (language use), Galaxy
Abstract: Although a stellar age accuracy of about 10 % seems to be a reasonable requirement to draw a time line in the evolution of our Galaxy as well as in the formation and evolution of exo-planetary systems, theoretical stellar models are at present still too imperfect to really achieve this goal. Asteroseismic observations are definitely of invaluable assistance, especially if individual pulsation frequencies are available, which is still far from common. Large stellar samples are now in the spotlight with two different lines of attack, spectroscopic and photometric surveys as well as asteroseismic missions. I shall review the problems arising from stellar physics in the context of large stellar samples of main sequence and red giant stars, and I shall raise some alarm bells but also highlight some positive news for a drastic improvement in stellar age determinations below the limit of 10 % in a foreseeable future.
Published: 2017

13. AIMS - a new tool for stellar parameter determinations using asteroseismic constraints

Author: Laura J. A. Scott, Tiago L. Campante, William J. Chaplin, Daniel R. Reese, Warrick H. Ball, Jiri Smetana, Mikkel N. Lund, Gaël Buldgen, Arlette Noels, B. M. Rendle, Richard Scuflaire, Andrea Miglio, James S. Kuszlewicz, Guy R. Davies, Benard Nsamba, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: stars, oscillations [stars], fundamental parameters -stars, fundamental parameters [stars], FOS: Physical sciences, Scale (descriptive set theory), 01 natural sciences, Asteroseismology, Synthetic data, symbols.namesake, Consistency (statistics), 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), [PHYS]Physics [physics], Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, Markov chain Monte Carlo, Grid, Bayesian statistics, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, oscillations, symbols, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Algorithm, QB799, Interpolation
Abstract: A key aspect in the determination of stellar properties is the comparison of observational constraints with predictions from stellar models. Asteroseismic Inference on a Massive Scale (AIMS) is an open source code that uses Bayesian statistics and a Markov Chain Monte Carlo approach to find a representative set of models that reproduce a given set of classical and asteroseismic constraints. These models are obtained by interpolation on a pre-calculated grid, thereby increasing computational efficiency. We test the accuracy of the different operational modes within AIMS for grids of stellar models computed with the Li\`ege stellar evolution code (main sequence and red giants) and compare the results to those from another asteroseismic analysis pipeline, PARAM. Moreover, using artificial inputs generated from models within the grid (assuming the models to be correct), we focus on the impact on the precision of the code when considering different combinations of observational constraints (individual mode frequencies, period spacings, parallaxes, photospheric constraints,...). Our tests show the absolute limitations of precision on parameter inferences using synthetic data with AIMS, and the consistency of the code with expected parameter uncertainty distributions. Interpolation testing highlights the significance of the underlying physics to the analysis performance of AIMS and provides caution as to the upper limits in parameter step size. All tests demonstrate the flexibility and capability of AIMS as an analysis tool and its potential to perform accurate ensemble analysis with current and future asteroseismic data yields., Comment: Accepted for publication in MNRAS. 17 pages, 17 figures
Published: 2019

14. 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 â stars: abundances â stars: fundamental parameters â stars: oscillations â 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

15. Mean density inversions for red giants and red clump stars

Author: Daniel R. Reese, Arlette Noels, Patrick Eggenberger, Andrea Miglio, Sébastien Salmon, Diego Bossini, R Scuflaire, B. M. Rendle, T Sonoi, Gaël Buldgen, Guy R. Davies, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Scaling law, 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, Inversion (meteorology), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Asteroseismology, Spectral line, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Stellar physics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Red clump, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics
Abstract: Since the CoRoT and Kepler missions, the availability of high quality seismic spectra for red giants has made them the standard clocks and rulers for Galactic Archeology. With the expected excellent data from the TESS and PLATO missions, red giants will again play a key role in Galactic studies and stellar physics, thanks to the precise masses and radii determined by asteroseismology. The determination of these quantities is often based on so-called scaling laws, which have been used extensively for main-sequence stars. We show how the SOLA inversion technique can provide robust determinations of the mean density of red giants within 1 per cent of the real value, using only radial oscillations. Combined with radii determinations from Gaia of around 2 per cent precision, this approach provides robust, less model-dependent masses with an error lower than 10 per cent. It will improve age determinations, helping to accurately dissect the Galactic structure and history. We present results on artificial data of standard models, models including an extended atmosphere from averaged 3D simulations and non-adiabatic frequency calculations to test surface effects, and on eclipsing binaries. We show that the inversions provide very robust mean density estimates, using at best seismic information. However, we also show that a distinction between red-giant branch and red-clump stars is required to determine a reliable estimate of the mean density. The stability of the inversion enables an implementation in automated pipelines, making it suitable for large samples of stars., Accepted for publication in MNRAS
Published: 2018
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16. Comprehensive stellar seismic analysis : New method exploiting the glitches information in solar-like pulsators

Author: Marc-Antoine Dupret, Arlette Noels, M. Farnir, G. Buldgen, and Sébastien Salmon
Subjects: Physics, 010504 meteorology & atmospheric sciences, Oscillation, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Asteroseismology, Glitch, Seismic analysis, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Orthonormal basis, Statistical physics, Degeneracy (mathematics), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Euclidean vector
Abstract: Aims: We develop a method that provides a comprehensive analysis of the oscillation spectra of solar-like pulsators. We define new seismic indicators that should be as uncorrelated and as precise as possible and should hold detailed information about stellar interiors. This is essential to improve the quality of the results obtained from asteroseismology as it will provide better stellar models which in turn can be used to refine inferences made in exoplanetology and galactic archaeology. Methods: The presented method - WhoSGlAd - relies on Gram-Schmidt's orthogonalisation process. A Euclidean vector subspace of functions is defined and the oscillation frequencies are projected over an orthonormal basis in a specific order. This allows the obtention of independent coefficients that we combine to define independent seismic indicators. Results: The developed method has been shown to be stable and to converge efficiently for solar-like pulsators. Thus, detailed and precise inferences can be obtained on the mass, the age, the chemical composition and the undershooting in the interior of the studied stars. However, attention has to be paid when studying the helium glitch as there seems to be a degeneracy between the influence of the helium abundance and that of the heavy elements on the glitch amplitude. As an example, we analyse the 16CygA (HD 186408) oscillation spectrum to provide an illustration of the capabilities of the method., Comment: Accepted for publication in Astronomy and Astrophysics, 20 pages
Published: 2018
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17. Red giants observed by CoRoT and APOGEE: The evolution of the Milky Way’s radial metallicity gradient

Author: Savita Mathur, K. Pan, Ivan Minchev, Mathias Schultheis, Cristina Chiappini, Josefina Montalbán, Andrea Miglio, Donald P. Schneider, Jon A. Holtzman, Rafael A. García, Frédéric Baudin, Arlette Noels-Grötsch, Steve Majewski, L. N. da Costa, Olga Zamora, Marica Valentini, Friedrich Anders, Timothy C. Beers, M. A. G. Maia, D. A. García-Hernández, Basilio X. Santiago, Matthias Steinmetz, Benoit Mosser, T. S. Rodrigues, 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), 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), Rheinisch-Westfälische Technische Hochschule Aachen University (RWTH), Space Science Institute [Boulder] (SSI), Institute for Advanced Biosciences / Institut pour l'Avancée des Biosciences (Grenoble) (IAB), Centre Hospitalier Universitaire [Grenoble] (CHU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Etablissement français du sang - Auvergne-Rhône-Alpes (EFS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures (DSMZ), RWTH Aachen University, Laboratoire Adaptation et pathogénie des micro-organismes [Grenoble] (LAPM), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Université de Franche-Comté (UFC), and 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)
Subjects: Cepheid variable, Metallicity, Milky Way, Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Disc, education, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, [PHYS]Physics [physics], education.field_of_study, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Interstellar medium, Stars, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Open cluster
Abstract: Using combined asteroseismic and spectroscopic observations of 418 red-giant stars close to the Galactic disc plane (6 kpc $, Comment: A&A, accepted. 12 pages + appendix, 8 figures. Improved Sec. 6
Published: 2017

18. Seismic inversion of the solar entropy: A case for improving the Standard Solar Model

Author: Peter Hakel, James Colgan, Arlette Noels, Daniel R. Reese, Marc-Antoine Dupret, Christopher J. Fontes, Patrick Eggenberger, G. Buldgen, Sébastien Salmon, Richard Scuflaire, Sylvaine Turck-Chièze, David P. Kilcrease, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), 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 Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire AIM, and Université Paris Diderot - Paris 7 ( UPD7 ) -Centre d'Etudes de Saclay
Subjects: Opacity, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], FOS: Physical sciences, Sun: fundamental parameters, Astrophysics, 7. Clean energy, 01 natural sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Helioseismology, Sun: oscillations, 010306 general physics, 010303 astronomy & astrophysics, Entropy (arrow of time), Solar and Stellar Astrophysics (astro-ph.SR), Physical quantity, Sun: helioseismology, Physics, Standard solar model, Astronomy and Astrophysics, Plasma, Geophysics, Stars, Astrophysics - Solar and Stellar Astrophysics, Convection zone, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: The Sun is the most constrained and well-studied of all stars. As a consequence, the physical ingredients entering solar models are used as a reference to study all other stars observed in the Universe. However, our understanding of the solar structure is still imperfect, as illustrated by the current debate on the heavy element abundances in the Sun. We wish to provide additional information on the solar structure by carrying out structural inversions of a new physical quantity, a proxy of the entropy of the solar plasma which properties are very sensitive to the temperature gradient below the convective zone. We use new structural kernels to carry out direct inversions of an entropy proxy of the solar plasma and compare the solar structure to various standard solar models built using various opacity tables and chemical abundances. We also link our results to classical tests commonly found in the literature. Our analysis allows us to probe more efficiently the uncertain regions of the solar models, just below the convective zone, paving the way for new in-depth analyses of the Sun taking into account additional physical uncertainties of solar models beyond the specific question of chemical abundances., Comment: Accepted for publication in Astronomy & Astrophysics
Published: 2017

19. Kepler red-clump stars in the field and in open clusters: constraints on core mixing

Author: J. Tayar, Santi Cassisi, A. Bressan, Diego Bossini, L. Girardi, Josefina Montalbán, Maurizio Salaris, M. Vrard, A. Pietrinferni, B. Mosser, Andrea Miglio, Arlette Noels, ITA, Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Astrophysical Research Institute [Liverpool], Liverpool John Moore University (ljmu), 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), Département d'astrophysique, Géophysique et Océanographie (AGO), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Collurania Astronomical Observatory, Department of Astronomy (Ohio State University), and Ohio State University [Columbus] (OSU)
Subjects: NGC 6791, HELIUM CONTENT, Metallicity, Population, THERMONUCLEAR REACTION-RATES, FOS: Physical sciences, MIXED-MODES, Astrophysics, asteroseismology, 01 natural sciences, Asteroseismology, Kepler-47, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, OSCILLATIONS, Astrophysics::Solar and Stellar Astrophysics, low-mass [stars], PERIOD SPACINGS, education, 010303 astronomy & astrophysics, Red clump, QC, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, QB, [PHYS]Physics [physics], Physics, interiors [stars], education.field_of_study, 010308 nuclear & particles physics, Astronomy, Astronomy and Astrophysics, Coupling (probability), Astrophysics - Astrophysics of Galaxies, Stars, Space and Planetary Science, STELLAR EVOLUTION, Astrophysics of Galaxies (astro-ph.GA), evolution [stars], GIANTS, ROTATION, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], CONVECTIVE CORES, Open cluster
Abstract: Convective mixing in Helium-core-burning (HeCB) stars is one of the outstanding issues in stellar modelling. The precise asteroseismic measurements of gravity-modes period spacing ($\Delta\Pi_1$) has opened the door to detailed studies of the near-core structure of such stars, which had not been possible before. Here we provide stringent tests of various core-mixing scenarios against the largely unbiased population of red-clump stars belonging to the old open clusters monitored by Kepler, and by coupling the updated precise inference on $\Delta\Pi_1$ in thousands field stars with spectroscopic constraints. We find that models with moderate overshooting successfully reproduce the range observed of $\Delta\Pi_1$ in clusters. In particular we show that there is no evidence for the need to extend the size of the adiabatically stratified core, at least at the beginning of the HeCB phase. This conclusion is based primarily on ensemble studies of $\Delta\Pi_1$ as a function of mass and metallicity. While $\Delta\Pi_1$ shows no appreciable dependence on the mass, we have found a clear dependence of $\Delta\Pi_1$ on metallicity, which is also supported by predictions from models., Comment: 8 pages, 4 figures, accepted for publication in MNRAS
Published: 2017

20. Asteroseismology of Massive Stars: Some Words of Caution

Author: Arlette Noels, Sébastien Salmon, Josefina Montalbán, Andrea Miglio, Maurice Gabriel, and Mélanie Godart
Subjects: Physics, Convection, Subgiant, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Asteroseismology, Stars, Supernova, Astrophysics - Solar and Stellar Astrophysics, Convection zone, Space and Planetary Science, Mixing length model, Astrophysics::Solar and Stellar Astrophysics, Schwarzschild radius, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: Although playing a key role in the understanding of the supernova phenomenon, the evolution of massive stars still suffers from uncertainties in their structure, even during their "quiet" main sequence phase and later on during their subgiant and helium burning phases. What is the extent of the mixed central region? In the local mixing length theory (LMLT) frame, are there structural differences using Schwarzschild or Ledoux convection criterion? Where are located the convective zone boundaries? Are there intermediate convection zones during MS and post-MS phase, and what is their extent and location? We discuss these points and show how asteroseismology could bring some light on these questions., Comment: 10 pages, 5 figures, IAU Symposium 307, New windows on massive stars: asteroseismology, interferometry, and spectropolarimetry, G. Meynet, C. Georgy, J.H. Groh & Ph. Stee, eds
Published: 2014

21. Investigating surface correction relations for RGB stars.

Author: Jørgensen, Andreas Christ Sølvsten, Montalbán, Josefina, Miglio, Andrea, Rendle, Ben M, Davies, Guy R, Buldgen, Gaël, Scuflaire, Richard, Noels, Arlette, Gaulme, Patrick, and García, Rafael A
Subjects: STELLAR oscillations, STELLAR structure, MAIN sequence (Astronomy), RED giants, AGE of stars, OPEN clusters of stars, STARS
Abstract: State-of-the-art stellar structure and evolution codes fail to adequately describe turbulent convection. For stars with convective envelopes such as red giants, this leads to an incomplete depiction of the surface layers. As a result, the predicted stellar oscillation frequencies are haunted by systematic errors, the so-called surface effect. Different empirically and theoretically motivated correction relations have been proposed to deal with this issue. In this paper, we compare the performance of these surface correction relations for red giant branch stars. For this purpose, we apply the different surface correction relations in asteroseismic analyses of eclipsing binaries and open clusters. In accordance with previous studies of main-sequence stars, we find that the use of different surface correction relations biases the derived global stellar properties, including stellar age, mass, and distance estimates. We, furthermore, demonstrate that the different relations lead to the same systematic errors for two different open clusters. Our results overall discourage from the use of surface correction relations that rely on reference stars to calibrate free parameters. Due to the demonstrated systematic biasing of the results, the use of appropriate surface correction relations is imperative to any asteroseismic analysis of red giants. Accurate mass, age, and distance estimates for red giants are fundamental when addressing questions that deal with the chemo-dynamical evolution of the Milky Way galaxy. In this way, our results also have implications for fields such as galactic archaeology that draw on findings from stellar physics. [ABSTRACT FROM AUTHOR]
Published: 2020
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22. Pulsations in hot supergiants

Author: Marc-Antoine Dupret, A. Grotsch-Noels, and Mélanie Godart
Subjects: Physics, COSMIC cancer database, Bright giant, media_common.quotation_subject, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Instability, Universe, Stars, Wolf–Rayet star, Space and Planetary Science, Blue supergiant, Astrophysics::Solar and Stellar Astrophysics, Supergiant, Astrophysics::Galaxy Astrophysics, media_common
Abstract: Massive stars are the cosmic engines that shape and drive our Universe. Many issues such as their formation, their stability and the mass loss effects, are far from being completely understood. Recent ground-based and space observations have shown pulsations in massive MS and post-MS stars, such as acoustic and gravity modes excited by the κ-mechanism and even solar-like oscillations. Theoretical studies emphasized the presence of strange modes in massive models, and recent theoretical analyses have shown that hot supergiants can pulsate in oscillatory convective modes. We review the instability domains of massive stars as well as their excitation mechanisms and present the latest results.
Published: 2013

23. Effects of the Coriolis force on high-order g modes in γ Doradus stars

Author: Sébastien Salmon, M.-P. Bouabid, Arlette Noels, M. A. Dupret, Andrea Miglio, and Josefina Montalbán
Subjects: Physics, T Tauri star, Stars, Space and Planetary Science, K-type main-sequence star, Astronomy and Astrophysics, Astrophysics, High order, Asteroseismology
Published: 2013

24. IV.1 Insights on the internal structure of stars as provided by seismology

Author: A. Grotsch-Noels, S. Deheuvels, and CoRot Team
Subjects: Physics, Stars, Structure (category theory), Astronomy, Astrophysics
Published: 2016

25. Testing the effects of opacity and the chemical mixture on the excitation of pulsations in B stars of the Magellanic Clouds

Author: Josefina Montalbán, Thierry Morel, Sébastien Salmon, Andrea Miglio, Alfred F. Noels, and Marc-Antoine Dupret
Subjects: Physics, Opacity, Astrophysics::High Energy Astrophysical Phenomena, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galaxy, Stars, Chemical mixtures, Iron group, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Small Magellanic Cloud, Astrophysics::Galaxy Astrophysics, Excitation, Kappa mechanism
Abstract: The B-type pulsators known as \beta Cephei and Slowly Pulsating B (SPB) stars present pulsations driven by the \kappa mechanism, which operates thanks to an opacity bump due to the iron group elements. In low-metallicity environments such as the Magellanic Clouds, \beta Cep and SPB pulsations are not expected. Nevertheless, recent observations show evidence for the presence of B-type pulsator candidates in both galaxies. We seek an explanation for the excitation of \beta Cep and SPB modes in those galaxies by examining basic input physics in stellar modelling: i) the specific metal mixture of B-type stars in the Magellanic Clouds; ii) the role of a potential underestimation of stellar opacities. We first derive the present-day chemical mixtures of B-type stars in the Magellanic Clouds. Then, we compute stellar models for that metal mixture and perform a non-adiabatic analysis of these models. In a second approach, we simulate parametric enhancements of stellar opacities due to different iron group elements. We then study their effects in models of B stars and their stability. We find that adopting a representative chemical mixture of B stars in the Small Magellanic Cloud cannot explain the presence of B-type pulsators there. An increase of the opacity in the region of the iron-group bump could drive B-type pulsations, but only if this increase occurs at the temperature corresponding to the maximum contribution of Ni to this opacity bump. We recommend an accurate computation of Ni opacity to understand B-type pulsators in the Small Magellanic Cloud, as well as the frequency domain observed in some Galactic hybrid \beta Cep-SPB stars.
Published: 2012

26. Asteroseismology of old open clusters with Kepler: direct estimate of the integrated red giant branch mass-loss in NGC 6791 and 6819

Author: Arlette Noels, B. Mosser, F. D'Antona, K. Brogaard, D. Stello, S. McCauliff, Róbert Szabó, Christopher K. Middour, S. Hekker, William J. Chaplin, S. Basu, Paolo Ventura, Jie Li, Alfio Bonanno, Frank Grundahl, V. Silva-Aguirre, T. Kallinger, Marc H. Pinsonneault, Josefina Montalbán, Andrea Miglio, Yvonne Elsworth, H. Kjeldsen, Alessandro Bressan, and A. M. Serenelli
Subjects: Physics, 010308 nuclear & particles physics, Astronomy, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Asteroseismology, Galaxy, Red-giant branch, Stars, Space and Planetary Science, 0103 physical sciences, Range (statistics), Cluster (physics), 010303 astronomy & astrophysics, Red clump, Open cluster
Abstract: Mass loss of red giant branch (RGB) stars is still poorly determined, despite its crucial role in the chemical enrichment of galaxies. Thanks to the recent detection of solar-like oscillations in G-K giants in open clusters with Kepler, we can now directly determine stellar masses for a statistically significant sample of stars in the old open clusters NGC6791 and NGC6819. The aim of this work is to constrain the integrated RGB mass loss by comparing the average mass of stars in the red clump (RC) with that of stars in the low-luminosity portion of the RGB (i.e. stars with L
Published: 2011

27. Kepler observations of the variability in B-type stars

Author: L. A. Balona, A. Pigulski, P. De Cat, G. Handler, J. Gutiérrez-Soto, C. A. Engelbrecht, F. Frescura, M. Briquet, J. Cuypers, J. Daszyńska-Daszkiewicz, P. Degroote, R. J. Dukes, R. A. Garcia, E. M. Green, U. Heber, S. D. Kawaler, H. Lehmann, B. Leroy, J. Molenda-Żakowicz, C. Neiner, A. Noels, J. Nuspl, R. Østensen, D. Pricopi, I. Roxburgh, S. Salmon, M. A. Smith, J. C. Suárez, M. Suran, R. Szabó, K. Uytterhoeven, null Christensen-Dalsgaard, H. Kjeldsen, D. A. Caldwell, F. R. Girouard, and D. T. Sanderfer
Subjects: Physics, Binary number, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Type (model theory), Rotation, Light curve, Instability, Spectral line, Stars, Space and Planetary Science, Modulation (music), Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: The analysis of the light curves of 48 B-type stars observed by Kepler is presented. Among these are 15 pulsating stars, all of which show low frequencies characteristic of SPB stars. Seven of these stars also show a few weak, isolated high frequencies and they could be considered as SPB/beta Cep hybrids. In all cases the frequency spectra are quite different from what is seen from ground-based observations. We suggest that this is because most of the low frequencies are modes of high degree which are predicted to be unstable in models of mid-B stars. We find that there are non-pulsating stars within the beta Cep and SPB instability strips. Apart from the pulsating stars, we can identify stars with frequency groupings similar to what is seen in Be stars but which are not Be stars. The origin of the groupings is not clear, but may be related to rotation. We find periodic variations in other stars which we attribute to proximity effects in binary systems or possibly rotational modulation. We find no evidence for pulsating stars between the cool edge of the SPB and the hot edge of the delta Sct instability strips. None of the stars show the broad features which can be attributed to stochastically-excited modes as recently proposed. Among our sample of B stars are two chemically peculiar stars, one of which is a HgMn star showing rotational modulation in the light curve.
Published: 2011

28. Seismic modelling of OB stars

Author: Dupret, Marc-Antoine, Godart, Mélanie, Belkacem, Kevin, Noels, Arlette, Wade, G., Meynet, Georges, Peters, Geraldine J., 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), Etoile, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Physics, Spiral galaxy, K-type main-sequence star, Astronomy, Astronomy and Astrophysics, Astrophysics, Compact star, Asteroseismology, Stars, T Tauri star, Space and Planetary Science, Stellar mass loss, Stellar dynamics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: A review of the ability of asteroseismology to probe the internal physics of OB stars is presented. The main constraints that can be obtained from the frequency spectrum in p- and g-modes pulsators are discussed. Next, we consider energetic aspects of the pulsations in OB stars and show how such study also allows to constrain their internal physics. The cases of p-mixed modes (β Cep stars), g-modes (SPB stars), strange modes and stochastically excited modes are considered.
Published: 2010

29. Overshooting and semiconvection: structural changes and asteroseismic signatures

Author: Mélanie Godart, Arlette Noels, Paolo Ventura, Andrea Miglio, and Josefina Montalbán
Subjects: Convection, Physics, Work (thermodynamics), Astronomy, Astronomy and Astrophysics, Astrophysics, Asteroseismology, Cosmology, Stars, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Stellar structure, Astrophysics::Earth and Planetary Astrophysics, Main sequence, Mixing (physics)
Abstract: Overshooting and semiconvection are two poorly known mechanisms which affect the extent and the efficiency of chemical mixing outside classical convection zones in stars. We discuss the uncertainties and the inferences of those processes in main sequence stars burning hydrogen in a convective core. We then focus on the asteroseismic signatures of partially or fully mixed zones surrounding the convective core, through the detailed shape of the induced chemical composition profile. We emphasize the potential power of asteroseismology to determine the internal structure of stars and thus to help us understand the physical processes at work inside the stars.
Published: 2009

30. Can mass loss and overshooting prevent the excitation of g-modes in blue supergiants?

Author: M. Godart, A. Noels, M.-A. Dupret, Y. Lebreton, Département des Sciences et Gestion de l'Environnement/Océanologie [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), SIMPA, Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: stars, mass-loss -stars, Convection, Opacity, FOS: Physical sciences, Astrophysics, 01 natural sciences, evolution -stars, 0103 physical sciences, Blue supergiant, Radiative transfer, Astrophysics::Solar and Stellar Astrophysics, stars: evolution, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, oscillations -supergiants, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 010308 nuclear & particles physics, supergiants, Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Stars, Astrophysics - Solar and Stellar Astrophysics, Convection zone, Space and Planetary Science, Excited state, stars: oscillations, Supergiant, stars: mass-loss
Abstract: Thanks to their past history on the main sequence phase, supergiant massive stars develop a convective shell around the helium core. This intermediate convective zone (ICZ) plays an essential role in governing which g-modes are excited. Indeed a strong radiative damping occurs in the high density radiative core but the ICZ acts as a barrier preventing the propagation of some g-modes into the core. These g-modes can thus be excited in supergiant stars by the kappa-mechanism in the superficial layers due to the opacity bump of iron, at log T=5.2. However massive stars are submitted to various complex phenomena such as rotation, magnetic fields, semiconvection, mass loss, overshooting. Each of these phenomena exerts a significant effect on the evolution and some of them could prevent the onset of the convective zone. We develop a numerical method which allows us to select the reflected, thus the potentially excited, modes only. We study different cases in order to show that mass loss and overshooting, in a large enough amount, reduce the extent of the ICZ and are unfavourable to the excitation of g-modes., 9 pages, 11 figures, accepted for publication in MNRAS
Published: 2009

31. CoRoT's view of newly discovered B-star pulsators: results for 358 candidate B pulsators from the initial run's exoplanet field data

Author: Michel Auvergne, Alfred F. Noels, J. Cuypers, W. W. Weiss, L. Balaguer-Núñez, Conny Aerts, Ignasi Ribas, M. Ollivier, Frédéric Baudin, Anne Thoul, Laurent Jorda, Maryline Briquet, Carla Maceroni, Magali Deleuil, P. De Cat, Andrea Miglio, Reza Samadi, Pieter Degroote, Annie Baglin, Josefina Montalbán, J. Debosscher, Institute of Astronomy, Katholieke Universiteit Leuven, Institut d'astrophysique spatiale (IAS), 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), Institut d'Astrophysique, Géophysique et Océanographie, Université de Liège, Koninklijke Sterrenwacht van België, Departament d'Astronomia i Meteorologia [Barcelona] (DAM), Universitat de Barcelona (UB), INAF-Osservatorio Astronomico di Roma (INAF-OAR), Institut de Ciencies de l'Espai (ICE), 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), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), and Universität Wien
Subjects: oscillations [stars], spaced data, opacity mechanism, Astronomy, FOS: Physical sciences, Astrophysics, Star (graph theory), 01 natural sciences, Instability, nyquist frequency, effective temperature, variable-stars, Planet, beta-cephei stars, pulsational frequency-analysis, 0103 physical sciences, data analysis [methods], Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Physics, 010308 nuclear & particles physics, time-series, photometric-observations, Astronomy and Astrophysics, Effective temperature, Exoplanet, Photometry (astronomy), Stars, Amplitude, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, variables: general [stars], order g-modes, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: We search for new variable B-type pulsators in the CoRoT data assembled primarily for planet detection, as part of CoRoT's Additional Programme. We aim to explore the properties of newly discovered B-type pulsators from the uninterrupted CoRoT space-based photometry and to compare them with known members of the Beta Cep and slowly pulsating B star (SPB) classes. We developed automated data analysis tools that include algorithms for jump correction, light-curve detrending, frequency detection, frequency combination search, and for frequency and period spacing searches. Besides numerous new, classical, slowly pulsating B stars, we find evidence for a new class of low-amplitude B-type pulsators between the SPB and Delta Sct instability strips, with a very broad range of frequencies and low amplitudes, as well as several slowly pulsating B stars with residual excess power at frequencies typically a factor three above their expected g-mode frequencies. The frequency data we obtained for numerous new B-type pulsators represent an appropriate starting point for further theoretical analyses of these stars, once their effective temperature, gravity, rotation velocity, and abundances will be derived spectroscopically in the framework of an ongoing FLAMES survey at the VLT., Comment: 22 pages, 30 figures, accepted for publication in A&A
Published: 2009

32. Probing the properties of convective cores through g modes: high-order g modes in SPB and γ Doradus stars

Author: P. Eggenberger, Andrea Miglio, Josefina Montalbán, and Arlette Noels
Subjects: Physics, Gravity (chemistry), Stellar mass, Astrophysics (astro-ph), FOS: Physical sciences, White dwarf, Astronomy and Astrophysics, Astrophysics, Asteroseismology, Spectral line, Stars, Amplitude, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, Main sequence
Abstract: In main sequence stars the periods of high-order gravity modes are sensitive probes of stellar cores and, in particular, of the chemical composition gradient that develops near the outer edge of the convective core. We present an analytical approximation of high-order g modes that takes into account the effect of the mu gradient near the core. We show that in main-sequence models, similarly to the case of white dwarfs, the periods of high-order gravity modes are accurately described by a uniform period spacing superposed to an oscillatory component. The periodicity and amplitude of such component are related, respectively, to the location and sharpness of the mu gradient. We investigate the properties of high-order gravity modes for stellar models in a mass domain between 1 and 10 Msun, and the effects of the stellar mass, evolutionary state, and extra-mixing processes on period spacing features. In particular, we show that for models of a typical SPB star, a chemical mixing that could likely be induced by the slow rotation observed in these stars, is able to significantly change the g-mode spectra of the equilibrium model. Prospects and challenges for the asteroseismology of gamma Doradus and SPB stars are also discussed., 18 pages, 29 figures, accepted for publication in MNRAS
Published: 2008

33. Polytropes as simple models of β Cephei stars

Author: Arlette Noels, R. Scuaire, Anne Thoul, and Mélanie Godart
Subjects: Physics, Stars, Simple (abstract algebra), Radiative transfer, Beta (velocity), Astrophysics, Polytropic process, Spectral line, Envelope (waves)
Abstract: Cephei stars have a simple structure: a convective core surrounded by a radiative envelope. It is therefore worth trying to describe Cephei stars with composite polytropes which are useful to retrieve structure parameters from frequency spectra. We show that the structure of Cephei models can relatively well be described with two-zone polytropic models. However this description is not convincing to depict oscillations of Cephei models.
Published: 2007

34. The Ε-mechanism in PMS and MS δ Scuti stars

Author: Richard Scuflaire, G. Lenain, Arlette Noels-Grötsch, and Marc-Antoine Dupret
Subjects: Physics, Oscillation, Astronomy, chemistry.chemical_element, Stellar core, Stars, Amplitude, chemistry, Ionization, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Helium, Excitation, Main sequence
Abstract: Scuti type stars are known to pulsate in nonradial low-order p and g modes. These oscillation modes are driven by the so-called -mechanism involving the second helium ionization zone. However, since g modes have signicant amplitudes near the stellar core, their excitation might be inuenced by the "-mechanism which is associated to the nuclear energy production. We investigate the eect of the "-mechanism on the stability of oscillation modes in 1.5 M pre-main sequence and main sequence stars.
Published: 2007

35. Young [$\alpha$/Fe]-enhanced stars discovered by CoRoT and APOGEE: What is their origin?

Author: Arlette Noels, M. A. G. Maia, Marie Martig, T. Morel, R. A. Garcia, Matthew Shetrone, Keivan G. Stassun, T. S. Rodrigues, Matthias Steinmetz, Sz. Meszaros, T. Kallinger, Paul Harding, Marica Valentini, Josefina Montalbán, D. P. Schneider, M. Schultheis, Friedrich Anders, J. A. Holtzman, R. de Assis Peralta, B. Mosser, S. Hekker, I. Minchev, L. N. da Costa, Andrea Miglio, C. Allende Prieto, Basilio X. Santiago, D. L. Nidever, N. Themeßl, S. R. Majewski, L. Girardi, S. Mathur, K. M. Cunha, F. Baudin, Cristina Chiappini, Timothy C. Beers, K. Pan, Ricardo P. Schiavon, Leibniz-Institut für Astrophysik Potsdam (AIP), 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), 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), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), 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)-Centre National d’Études Spatiales [Paris] (CNES), European Project: 338251,EC:FP7:ERC,ERC-2013-StG,STELLARAGES(2013), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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, and 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)
Subjects: RED-GIANT STARS, Milky Way, fundamental parameters [stars], MILKY-WAY DISK, Astrophysics, asteroseismology, Astrophysics::Cosmology and Extragalactic Astrophysics, Spectral line, Formacao de galaxias, Galaxy: disk, STELLAR POPULATIONS, SOLAR VICINITY, stellar content [Galaxy], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics, QB, Physics, Galaxy: stellar content, Spiral galaxy, Galactic Center, 1ST YEAR, abundances [Galaxy], Astronomy and Astrophysics, ELEMENTAL ABUNDANCE, Alpha (navigation), CHEMICAL ABUNDANCES, CHEMODYNAMICAL EVOLUTION, Astrophysics - Astrophysics of Galaxies, Chemical evolution, Stars, formation [Galaxy], Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Galaxy: formation, Asterosismologia, Galaxy: abundances, stars: fundamental parameters, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], disk [Galaxy], NEARBY STARS, GALACTIC-CENTER
Abstract: We report the discovery of a group of apparently young CoRoT red-giant stars exhibiting enhanced [alpha/Fe] abundance ratios (as determined from APOGEE spectra) with respect to Solar values. Their existence is not explained by standard chemical evolution models of the Milky Way, and shows that the chemical-enrichment history of the Galactic disc is more complex. We find similar stars in previously published samples for which isochrone-ages could be robustly obtained, although in smaller relative numbers, which could explain why these stars have not received prior attention. The young [alpha/Fe]-rich stars are much more numerous in the CoRoT-APOGEE (CoRoGEE) inner-field sample than in any other high-resolution sample available at present, as only CoRoGEE can explore the inner-disc regions and provide ages for its field stars. The kinematic properties of the young [$\alpha$/Fe]-rich stars are not clearly thick-disc like, despite their rather large distances from the Galactic mid-plane. Our tentative interpretation of these and previous intriguing observations in the Milky Way is that these stars were formed close to the end of the Galactic bar, near corotation -- a region where gas can be kept inert for longer times, compared to other regions shocked more frequently by the passage of spiral arms. Moreover, that is where the mass return from older inner-disc stellar generations should be maximal (according to an inside-out disc-formation scenario), further diluting the in-situ gas. Other possibilities to explain these observations (e.g., a recent gas-accretion event) are also discussed., Comment: Letter in press in Astronomy and Astrophysics (5 pages, 4 figures + 2 pages Appendix)
Published: 2015

36. Uncertainties on near-core mixing in red-clump stars: effects on the period spacing and on the luminosity of the AGB bump

Author: Arlette Noels, Andrea Miglio, Josefina Montalbán, Maurizio Salaris, Paola Marigo, Santi Cassisi, Adriano Pietrinferni, Diego Bossini, L. Girardi, Alessandro Bressan, and ITA
Subjects: European community, FOS: Physical sciences, MIXED-MODES, POPULATION SYNTHESIS, Stars: late-type, asteroseismology, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galactic nuclei, Grant funding, Luminosity, HORIZONTAL-BRANCH STARS, Settore FIS/05 - Astronomia e Astrofisica, GLOBULAR-CLUSTERS, Asteroseismology, Stars: evolution, Stars: interiors, Stars: low-mass, Space and Planetary Science, Astronomy and Astrophysics, Astrophysics::Solar and Stellar Astrophysics, low-mass [stars], WHITE-DWARFS, Red clump, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), interiors [stars], Physics, Astronomy, Horizontal branch, stars: evolution, stars: interiors, stars: late-type, stars: low-mass, OLD OPEN CLUSTERS, NGC 6819, Stars, Astrophysics - Solar and Stellar Astrophysics, evolution [stars], ASYMPTOTIC GIANT BRANCH, late-type [stars], Christian ministry, Astrophysics::Earth and Planetary Astrophysics, STELLAR EVOLUTION DATABASE, CONVECTIVE CORES
Abstract: Low-mass stars in the He-core-burning phase (HeCB) play a major role in stellar, galactic, and extragalactic astrophysics. The ability to predict accurately the properties of these stars, however, depends on our understanding of convection, which remains one of the key open questions in stellar modelling. We argue that the combination of the luminosity of the AGB bump (AGBb) and the period spacing of gravity modes (DP) during the HeCB phase, provides us with a decisive test to discriminate between competing models of these stars. We use the MESA, BaSTI, and PARSEC stellar evolution codes to model a typical giant star observed by Kepler. We explore how various near-core-mixing scenarios affect the predictions of the above-mentioned constraints, and we find that DP depends strongly on the prescription adopted. Moreover we show that the detailed behaviour of DP shows the signature of sharp variations in the Brunt-Vaisala frequency, which could potentially give additional information about near-core features. We find evidence for the AGBb among Kepler targets, and a first comparison with observations shows that, even if standard models are able to reproduce the luminosity distribution, no standard model can account for satisfactorily the period spacing of HeCB stars. Our analysis allows us to outline a candidate model to describe simultaneously the two observed distributions: a model with a moderate overshooting region characterized by an adiabatic thermal stratification. This prescription will be tested in the future on cluster stars, to limit possible observational biases., Comment: 13 pages, 10 figures, accepted for publication in MNRAS
Published: 2015
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37. The AGB bump: A calibrator for core mixing

Author: Léo Girardi, Maurizio Salaris, Alessandro Bressan, Arlette Noels, Andrea Miglio, Diego Bossini, Paola Marigo, and Josefina Montalbán
Subjects: Convection, Physics, QC1-999, FOS: Physical sciences, White dwarf, Observable, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Horizontal branch, Luminosity, Stars, Physics and Astronomy (all), Astrophysics - Solar and Stellar Astrophysics, Asymptotic giant branch, Astrophysics::Solar and Stellar Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Mixing (physics), Astrophysics::Galaxy Astrophysics
Abstract: The efficiency of convection in stars affects many aspects of their evolution and remains one of the key-open questions in stellar modelling. In particular, the size of the mixed core in core-He-burning low-mass stars is still uncertain and impacts the lifetime of this evolutionary phase and, e.g., the C/O profile in white dwarfs. One of the known observables related to the Horizontal Branch (HB) and Asymptotic Giant Branch (AGB) evolution is the AGB bump. Its luminosity depends on the position in mass of the helium-burning shell at its first ignition, that is affected by the extension of the central mixed region. In this preliminary work we show how various assumptions on near-core mixing and on the thermal stratification in the overshooting region affect the luminosity of the AGB bump, as well as the period spacing of gravity modes in core-He-burning models., Submitted to EPJ Web of Conferences, to appear in the Proceedings of the 3rd CoRoT Symposium, Kepler KASC7 joint meeting; 2 pages, 2 figures
Published: 2015

38. Combining multiple structural inversions to constrain the solar modelling problem.

Author: Buldgen, G., Salmon, S. J. A. J., Noels, A., Scuflaire, R., Montalban, J., Baturin, V. A., Eggenberger, P., Gryaznov, V. K., Iosilevskiy, I. L., Meynet, G., Chaplin, W. J., Miglio, A., Oreshina, A. V., Richard, O., and Starostin, A. N.
Subjects: STARS, PHYSICS, ENTROPY, HELIUM, CONVECTION (Astrophysics)
Abstract: Context. The Sun is the most studied of all stars, which serves as a reference for all other observed stars in the Universe. Furthermore, it also serves the role of a privileged laboratory of fundamental physics and can help us better understand processes occuring in conditions irreproducible on Earth. However, our understanding of our star is currently lessened by the so-called solar modelling problem, resulting from comparisons of theoretical solar models to helioseismic constraints. These discrepancies can stem from various causes, such as the radiative opacities, the equation of state as well as the mixing of the chemical elements. Aims. By analysing the potential of combining information from multiple seismic inversions, our aim is to help disentangle the origins of the solar modelling problem. Methods. We combined inversions of the adiabatic sound speed, an entropy proxy and the Ledoux discriminant with other constraints such as the position of the base of the convective zone and the photospheric helium abundance. First, we tested various combinations of standard ingredients available for solar modelling such as abundance tables, equation of state, formalism for convection and diffusion and opacity tables. Second, we studied the diagnostic potential of the inversions on models including ad hoc modifications of the opacity profile and additional mixing below the convective envelope. Results. We show that combining inversions provides stringent constraints on the required modifications to the solar ingredients, far beyond what can be achieved from sound speed inversions alone. We constrain the form and amplitude of the opacity increase required in solar models and show that a 15% increase at log T = 6.35 provides a significant improvement, but is insufficient on its own. A more global increase in the opacity, within the uncertainties of the current tables, coupled with a localized additional mixing at the bottom of the convective zone provides the best agreement for low-metallicity models. We show that high-metallicity models do not satisfy all the inversion results. We conclude that the solar modelling problem likely occurs from multiple small contributors, as other ingredients such as the equation of state or the formalism of convection can induce small but significant changes in the models and that using phase shift analyses combined with our approach is the next step for a better understanding of the inaccuracies of solar models just below the convective envelope. [ABSTRACT FROM AUTHOR]
Published: 2019
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39. [Untitled]

Author: Arlette Noels-Grötsch, Marc-Antoine Dupret, Conny Aerts, J. De Ridder, Richard Scuflaire, Andrés Moya, P. De Cat, R. Garrido, and Anne Thoul
Subjects: Delta, Physics, Identification (information), Stars, Space and Planetary Science, Mode (statistics), Astronomy and Astrophysics, Improved method, Beta (velocity), Astrophysics
Published: 2003

40. Accretion of gas by globular cluster stars

Author: Emmanuel Jehin, Alain Jorissen, Stéphane Goriely, Anne Thoul, Pierre Magain, Alfred F. Noels, and Geneviève Parmentier
Subjects: Physics, education.field_of_study, Subgiant, Astrophysics (astro-ph), Population, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Giant star, Accretion (astrophysics), Stars, Space and Planetary Science, Globular cluster, Cluster (physics), Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Halo, education, Astrophysics::Galaxy Astrophysics
Abstract: Some recent observations of the abundances of s-process, r-process, and alpha elements in metal-poor stars have led to a new scenario for their formation. According to this scenario, these stars were born in a globular cluster and accreted the s-process enriched gas expelled by cluster stars of higher-mass, thereby modifying their surface abundances. Later on, these polluted stars evaporated from the globular cluster to constitute an important fraction of the current halo population. In addition, there are now many direct observations of abundance anomalies not only in globular cluster giant stars but also in subgiant and main-sequence stars. Accretion provides again a plausible explanation for (at least some of) these peculiarities. Here we investigate further the efficiency of the accretion scenario. We find that in concentrated clusters with large escape velocities, accretion is very efficient and can indeed lead to major modifications of the stellar surface abundances., Comment: 11 pages; accepted for publication in Astronomy and Astrophysics
Published: 2002

41. Determining stellar parameters of asteroseismic targets: going beyond the use of scaling relations

Author: Arlette Noels, Andrea Miglio, Paola Marigo, Léo Girardi, Josefina Montalbán, Michele Trabucchi, H. R. Coelho, Diego Bossini, and T. S. Rodrigues
Subjects: RED-GIANT STARS, CLUSTER NGC 6819, Hertzsprung–Russell diagram, magnitude diagrams, fundamental parameters [stars], ECLIPSING BINARY, FOS: Physical sciences, MIXED-MODES, KEPLER INPUT CATALOG, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Hertzsprung-Russell and colour-magnitude diagrams, Stars: fundamental parameters, Astronomy and Astrophysics, Space and Planetary Science, 01 natural sciences, Luminosity, Kepler Input Catalog, symbols.namesake, 0103 physical sciences, ASTROPHYSICS MESA, Astrophysics::Solar and Stellar Astrophysics, Solar-like oscillations, PERIOD SPACINGS, MAIN-SEQUENCE, 010303 astronomy & astrophysics, Scaling, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, Estimation theory, Astronomy, Russell and colour, EVOLUTION, Galaxy, Stars, Hertzsprung, Astrophysics - Solar and Stellar Astrophysics, symbols, Astrophysics::Earth and Planetary Astrophysics, SOLAR-LIKE OSCILLATIONS
Abstract: Asteroseismic parameters allow us to measure the basic stellar properties of field giants observed far across the Galaxy. Most of such determinations are, up to now, based on simple scaling relations involving the large frequency separation, \Delta\nu, and the frequency of maximum power, \nu$_{max}$. In this work, we implement \Delta\nu\ and the period spacing, {\Delta}P, computed along detailed grids of stellar evolutionary tracks, into stellar isochrones and hence in a Bayesian method of parameter estimation. Tests with synthetic data reveal that masses and ages can be determined with typical precision of 5 and 19 per cent, respectively, provided precise seismic parameters are available. Adding independent information on the stellar luminosity, these values can decrease down to 3 and 10 per cent respectively. The application of these methods to NGC 6819 giants produces a mean age in agreement with those derived from isochrone fitting, and no evidence of systematic differences between RGB and RC stars. The age dispersion of NGC 6819 stars, however, is larger than expected, with at least part of the spread ascribable to stars that underwent mass-transfer events., Comment: 17 pages, 13 figures, accepted for publication in MNRAS
Published: 2017

42. The PLATO 2.0 mission

Author: Rauer, H., Catala, C., Aerts, C., Appourchaux, T., Benz, W., Brandeker, A., Christensen-Dalsgaard, J., Deleuil, M., Gizon, L., Goupil, M. -J., G��del, M., Janot-Pacheco, E., Mas-Hesse, M., Pagano, I., Piotto, G., Pollacco, D., Santos, N. C., Smith, A., C., J., Su��rez, Szab��, R., Udry, S., Adibekyan, V., Alibert, Y., Almenara, J. -M., Amaro-Seoane, P., Eiff, M. Ammler-von, Asplund, M., Antonello, E., Ball, W., Barnes, S., Baudin, F., Belkacem, K., Bergemann, M., Bihain, G., Birch, A. C., Bonfils, X., Boisse, I., Bonomo, A. S., Borsa, F., Brand��o, I. M., Brocato, E., Brun, S., Burleigh, M., Burston, R., Cabrera, J., Cassisi, S., Chaplin, W., Charpinet, S., Chiappini, C., Church, R. P., Csizmadia, Sz., Cunha, M., Damasso, M., Davies, M. B., Deeg, H. J., D��az, R. F., Dreizler, S., Dreyer, C., Eggenberger, P., Ehrenreich, D., Eigm��ller, P., Erikson, A., Farmer, R., Feltzing, S., Fialho, F. de Oliveira, Figueira, P., Forveille, T., Fridlund, M., Garc��a, R. A., Giommi, P., Giuffrida, G., Godolt, M., da Silva, J. Gomes, Granzer, T., Grenfell, J. L., Grotsch-Noels, A., G��nther, E., Haswell, C. A., Hatzes, A. P., H��brard, G., Hekker, S., Helled, R., Heng, K., Jenkins, J. M., Johansen, A., Khodachenko, M. L., Kislyakova, K. G., Kley, W., Kolb, U., Krivova, N., Kupka, F., Lammer, H., Lanza, A. F., Lebreton, Y., Magrin, D., Marcos-Arenal, P., Marrese, P. M., Marques, J. P., Martins, J., Mathis, S., Mathur, S., Messina, S., Miglio, A., Montalban, J., Montalto, M., Monteiro, M. J. P. F. G., Moradi, H., Moravveji, E., Mordasini, C., Morel, T., Mortier, A., Nascimbeni, V., Nelson, R. P., Nielsen, M. B., Noack, L., Norton, A. J., Ofir, A., Oshagh, M., Ouazzani, R. -M., P��pics, P., Parro, V. C., Petit, P., Plez, B., Poretti, E., Quirrenbach, A., Ragazzoni, R., Raimondo, G., Rainer, M., Reese, D. R., Redmer, R., Reffert, S., Rojas-Ayala, B., Roxburgh, I. W., Salmon, S., Santerne, A., Schneider, J., Schou, J., Schuh, S., Schunker, H., Silva-Valio, A., Silvotti, R., Skillen, I., Snellen, I., Sohl, F., Sousa, S. G., Sozzetti, A., Stello, D., Strassmeier, K. G., ��vanda, M., Szab��, Gy. M., Tkachenko, A., Valencia, D., van Grootel, V., Vauclair, S. D., Ventura, P., Wagner, F. W., Walton, N. A., Weingrill, J., Werner, S. C., Wheatley, P. J., Zwintz, K., DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Instituut voor Sterrenkunde [Leuven], Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Stockholm University, Stellar Astrophysics Centre [Aarhus] (SAC), Aarhus University [Aarhus], Department of Palaeontology, National Institutes of Health [Bethesda] (NIH)-The Natural History Museum (NHM), Laboratoire d'Informatique Avancée de Saint-Denis (LIASD), Université Paris 8 Vincennes-Saint-Denis (UP8), High Speed Networks Laboratory, Dept. of Telecommunications and Media Informatics, Budapest University of Technology and Economics [Budapest] (BME), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève = University of Geneva (UNIGE), Laboratoire d'astrophysique de l'observatoire de Besançon (UMR 6091) (LAOB), 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), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes - UFR Pharmacie (UGA UFRP), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Department of Physics and Astronomy [Leicester], University of Leicester, Institute for Digital Communication Joint Research Institute for Signal & Image Processing School of Engineering and Electronics - University of Edinburgh, University of Edinburgh, Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), DLR Institute of Planetary Research, German Aerospace Center (DLR), UCLA Economics, University of California [Los Angeles] (UCLA), University of California (UC)-University of California (UC), Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto = University of Porto, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Nottingham Transportation Engineering Centre, University of Nottingham, UK (UON), Thüringer Landessternwarte Tautenburg (TLS), Tel Aviv University (TAU), Center for Space and Habitability (CSH), University of Bern, Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Département Langues et Culture Internationale (LCI), Université européenne de Bretagne - European University of Brittany (UEB)-Télécom Bretagne-Institut Mines-Télécom [Paris] (IMT), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), School of Physical Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, CTS/UNINOVA, Faculty of Sciences and Technology, Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, School of Physics and Astronomy, University of Birmingham [Birmingham], Departamento de Física e Astronomia [Porto] (DFA/FCUP), Faculdade de Ciências da Universidade do Porto (FCUP), Universidade do Porto = University of Porto-Universidade do Porto = University of Porto, Danmarks Tekniske Universitet = Technical University of Denmark (DTU), 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)-Centre National de la Recherche Scientifique (CNRS), LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Institut für Physik, Universität Rostock, Landessternwarte Königstuhl [ZAH] (LSW), Universität Heidelberg [Heidelberg] = Heidelberg University, Mécanismes adaptatifs : des organismes aux communautés (MAOAC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Historisches Institut, Universität Paderborn (UPB), Hansen Experimental Physics Lab [Stanford] (HEPL), Stanford University, Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Department of Experimental Physics, University of Szeged [Szeged], ELTE Gothard Astrophysical Observatory, Eötvös Loránd University (ELTE), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), 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), Juelich Centre for Neutron Science, IFF, Forschungszentrum Juelich, Institut fuer Festkoerperforschung Juelich, Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universität Bern [Bern], Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université de Genève (UNIGE), Laboratoire d'astrophysique de l'observatoire de Besançon (LAOB), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Université Grenoble Alpes (UGA), University of California-University of California, Universidade do Porto [Porto], Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), European Space Agency (ESA)-European Space Agency (ESA), Tel Aviv University [Tel Aviv], Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), The Open University [Milton Keynes] (OU), Max-Planck-Institut für Sonnensystemforschung (MPS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Osaka City University Advanced Mathematical Institute (OCAMI), Osaka Media Center, Technical University of Denmark [Lyngby] (DTU), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Universität Heidelberg [Heidelberg], Muséum national d'Histoire naturelle (MNHN)-Collège de France (CdF)-Centre National de la Recherche Scientifique (CNRS), Hansen Experimental Physics Laboratory (HEPL), Stanford University [Stanford], ELTE Gao-Lendulet Research Group, Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Low Energy Astrophysics (API, FNWI), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Universidade do Porto, Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Osaka City university Advanced Mathematical Institute [Osaka] (OCAMI), Osaka City University (OCU), 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 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), 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), and Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)
Subjects: photometry, Gas giant, 530 Physics, FOS: Physical sciences, asteroseismology, Astrophysics::Cosmology and Extragalactic Astrophysics, transit surey, Asteroseismology, INSTRUMENTAÇÃO (ASTRONOMIA), Planet, Astrophysics::Solar and Stellar Astrophysics, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Seismaology, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Exoplanetary science, Planetary habitability, Exoplanets, 520 Astronomy, Stellar science, Astronomy, Astronomy and Astrophysics, Planetary system, 620 Engineering, Exoplanet, Stars, exoplanets, 13. Climate action, Space and Planetary Science, Transit survey, Terrestrial planet, Astrophysics::Earth and Planetary Astrophysics, Circumstellar habitable zone, Astrophysics - Earth and Planetary Astrophysics
Abstract: PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 sec readout cadence and 2 with 2.5 sec candence) providing a wide field-of-view (2232 deg2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2%, 4-10% and 10% for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50% of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0., Comment: 63 pages, 17 figures, submitted to Experimental Astronomy (ExA)
Published: 2014

43. The IACOB project

Author: Sergio Simón-Díaz, Paolo Ventura, S. Salmon, A. Herrero, M. A. Dupret, Mélanie Godart, and A. Grotsch-Noels
Subjects: Physics, 010308 nuclear & particles physics, Mode (statistics), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Instability, Asteroseismology, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Supergiant, Adiabatic process, 010303 astronomy & astrophysics, Stellar evolution, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, O-type star
Abstract: Asteroseismology is a powerful tool to access the internal structure of stars. Apart from the important impact of theoretical developments, progress in this field has been commonly associated with the analysis of time-resolved observations. Recently, the so-called macroturbulent broadening has been proposed to be a complementary and less expensive way -- in terms of observational time -- to investigate pulsations in massive stars. We assess to what extent this ubiquitous non-rotational broadening component shaping the line profiles of O stars and B supergiants is a spectroscopic signature of pulsation modes driven by a heat mechanism. We compute stellar main sequence and post-main sequence models from 3 to 70Msun with the ATON stellar evolution code and determine the instability domains for heat-driven modes for degrees l=1-20 using the adiabatic and non-adiabatic codes LOSC and MAD. We use the observational material presented in Sim\'on-D\'iaz et al. (2016) to investigate possible correlations between the single snapshot line-broadening properties of a sample of ~260 O and B-type stars and their location inside/outside the various predicted instability domains. We present an homogeneous prediction for the non-radial instability domains of massive stars for degree l up to 20. We provide a global picture of what to expect from an observational point of view in terms of frequency range of excited modes, and investigate the behavior of the instabilities with stellar evolution and increasing degree of the mode. Furthermore, our pulsational stability analysis, once compared to the empirical results of Sim\'on-D\'iaz et al. (2016), indicates that stellar oscillations originated by a heat mechanism can not explain alone the occurrence of the large non-rotational line-broadening component commonly detected in the O star and B supergiant domain., Comment: 14 pages, 8 figures, Reproduced with permission from Astronomy & Astrophysics, \c{opyright} ESO
Published: 2016

44. Apsidal motion in the massive binary HD 152218

Author: J. H. M. M. Schmitt, M. A. Dupret, Sophie Rosu, Arlette Noels, Grégor Rauw, Mélanie Godart, Laurent Mahy, and E. Gosset
Subjects: Physics, Solar mass, education.field_of_study, 010308 nuclear & particles physics, Apsidal precession, Population, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Radial velocity, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Stellar physics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, education, 010303 astronomy & astrophysics, Stellar evolution, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Open cluster
Abstract: Massive binary systems are important laboratories in which to probe the properties of massive stars and stellar physics in general. In this context, we analysed optical spectroscopy and photometry of the eccentric short-period early-type binary HD 152218 in the young open cluster NGC 6231. We reconstructed the spectra of the individual stars using a separating code. The individual spectra were then compared with synthetic spectra obtained with the CMFGEN model atmosphere code. We furthermore analysed the light curve of the binary and used it to constrain the orbital inclination and to derive absolute masses of 19.8 +/- 1.5 and 15.0 +/- 1.1 solar masses. Combining radial velocity measurements from over 60 years, we show that the system displays apsidal motion at a rate of (2.04^{+.23}_{-.24}) degree/year. Solving the Clairaut-Radau equation, we used stellar evolution models, obtained with the CLES code, to compute the internal structure constants and to evaluate the theoretically predicted rate of apsidal motion as a function of stellar age and primary mass. In this way, we determine an age of 5.8 +/- 0.6 Myr for HD 152218, which is towards the higher end of, but compatible with, the range of ages of the massive star population of NGC 6231 as determined from isochrone fitting., Accepted for publication in Astronomy & Astrophysics
Published: 2016

45. Differential population studies using asteroseismology: Solar-like oscillating giants in CoRoT fields LRc01 and LRa01

Author: Cristina Chiappini, Josefina Montalbán, William J. Chaplin, Mauro Barbieri, Alfred F. Noels, Benoit Mosser, Frédéric Baudin, V. Silva Aguirre, Annie Baglin, M. Valentini, Luca Fossati, Léo Girardi, Andrea Miglio, Thierry Morel, Luca Casagrande, 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), Etoile, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Physics, education.field_of_study, Milky Way, QC1-999, Population, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Giant star, Asteroseismology, Astrophysics - Astrophysics of Galaxies, Spectral line, Stars, Astrophysics - Solar and Stellar Astrophysics, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], education, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics
Abstract: Solar-like oscillating giants observed by the space-borne satellites CoRoT and Kepler can be used as key tracers of stellar populations in the Milky Way. When combined with additional photometric/spectroscopic constraints, the pulsation spectra of solar-like oscillating giant stars not only reveal their radii, and hence distances, but also provide well-constrained estimates of their masses, which can be used as proxies for the ages of these evolved stars. In this contribution we provide supplementary material to the comparison we presented in Miglio et al. (2013) between populations of giants observed by CoRoT in the fields designated LRc01 and LRa01., Comment: 11 pages, 7 figures, to appear in proceedings of 40th Liege International Astrophysical Colloquium 'Ageing low-mass stars: from red giants to white dwarfs'
Published: 2013

46. Non-radial, non-adiabatic solar-like oscillations in RGB and HB stars

Author: Josefina Montalbán, Kevin Belkacem, Alfred F. Noels, Marc-Antoine Dupret, R. Samadi, and M. Grosjean
Subjects: Physics, Hertzsprung–Russell diagram, media_common.quotation_subject, QC1-999, FOS: Physical sciences, Astrophysics, Inertia, Asteroseismology, Spectral line, Stars, symbols.namesake, Amplitude, Astrophysics - Solar and Stellar Astrophysics, symbols, Astrophysics::Solar and Stellar Astrophysics, Solar-like oscillations, Astrophysics::Earth and Planetary Astrophysics, Adiabatic process, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), media_common
Abstract: CoRoT and Kepler observations of red giants reveal rich spectra of non-radial solar-like oscillations allowing to probe their internal structure. We compare the theoretical spectrum of two red giants in the same region of the HR diagram but in different evolutionary phases. We present here our first results on the inertia, lifetimes and amplitudes of the oscillations and discuss the differences between the two stars., Comment: 40th Liege International Astrophysical Colloquium, 2 pages, 3 figures
Published: 2013
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47. Testing convective-core overshooting using period spacings of dipole modes in red giants

Author: Richard Scuflaire, Andrea Miglio, Paolo Ventura, Marc-Antoine Dupret, Josefina Montalbán, and Arlette Noels
Subjects: Physics, FOS: Physical sciences, Astronomy and Astrophysics, Observable, Astrophysics, Giant star, Asteroseismology, Red-giant branch, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Adiabatic process, Red clump, Stellar evolution, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: Uncertainties on central mixing in main sequence (MS) and core He-burning (He-B) phases affect key predictions of stellar evolution such as late evolutionary phases, chemical enrichment, ages etc. We propose a test of the extension of extra-mixing in two relevant evolutionary phases based on period spacing Delta_P of solar-like oscillating giants. From stellar models and their corresponding adiabatic frequencies (respectively computed with ATON and LOSC codes) we provide the first predictions of the observable Delta_P for stars in the red giant branch (RGB) and in the red clump (RC). We find: i) a clear correlation between Delta_P and the mass of the helium core (M_He); the latter in intermediate-mass stars depends on the MS overshooting, hence it can be used to set constraints on extra mixing during MS when coupled with chemical composition; ii) a linear dependence of the average value of the asymptotic period spacing (_a) during the He-B phase on the size of the convective core. A first comparison with the inferred asymptotic period spacing for Kepler RC stars suggests the need for extra mixing also during this phase, as evinced from other observational facts., Comment: 19 pages, 8 figures, accepted for publication in ApJ
Published: 2013
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48. Semi-convection: What Is the Underlying Physical Context?

Author: Arlette Noels
Subjects: Proton–proton chain reaction, Physics, Stars, CNO cycle, Opacity, Stellar mass, Radiation pressure, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics, Total pressure, Instability, Astrophysics::Galaxy Astrophysics
Abstract: Stellar conditions leading to a possible semi-convective mixing are discussed in three relevant cases: (1) low-mass MS stars in which the CNO cycle takes progressively the lead over the PP chain due to the increase in temperature as core hydrogen burning proceeds, (2) massive MS stars which experience a large contribution of the radiation pressure to the total pressure, and (3) core-helium-burning stars for which the production of carbon in the core increases the opacity. A short discussion of semi-convection in terms of instability of non-radial modes follows.
Published: 2013

49. Red Giants as Probes of the Structure and Evolution of the Milky Way

Author: Arlette Noels, Andrea Miglio, and Josefina Montalbán
Subjects: Physics, Astrophysics and Astronomy, Stellar population, Red giant, Milky Way, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Asteroseismology, Galaxy, Stars, Globular cluster, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Stellar evolution, Astrophysics::Galaxy Astrophysics
Abstract: Part I Asteroseismology of red giants.- Aspects of observational red giant population seismology.- Asteroseismology of red giants as a tool for studying stellar populations: first steps.- Adiabatic solar-like oscillations in red giant stars.- Energetic aspects of non-radial solar-like oscillations in red giants.- Part II Internal structure, atmosphere, and evolution of red giants: current models and their uncertainties.- Evolution and internal structure of red giants.- Uncertainties and systematics in stellar evolution models of Red Giant Stars.- Convection modelling and the morphology of RGBs in stellar clusters.- Helium burning in moderate-mass stars.- Hydrodynamic simulations of shell convection in stellar cores.- Impact of rotational mixing on the global and asteroseismic properties of red giants.- 3D picture of the convective envelope of a rotating RGB star.- Effects of rotation and thermohaline mixing in red giant stars.- 3D Model Atmospheres of Red Giant Stars.- Part III Stellar populations in the Milky Way.- Structure and Evolution of the Milky Way.- Red Giant stars: probing the MilkyWay chemical enrichment.- Chemical abundances of giants in globular clusters.- TRILEGAL, a TRIdimensional modeL of thE GALaxy: status and future.- The Besanc,on model of stellar population synthesis of the Galaxy.
Published: 2012

50. Atomic data and solar and stellar spectroscopy

Author: A Noels and N Grevesse
Subjects: Physics, Photosphere, Astronomy, Astrophysics, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Abundance of the chemical elements, Astronomical spectroscopy, Stars, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Emission spectrum, Spectroscopy, Astrophysics::Galaxy Astrophysics, Mathematical Physics, Atomic data
Abstract: Solar photospheric abundances, which are generally used as references for other stars, are now, on the whole, in very good agreement with the meteoritic abundances. This is not due to progress in solar spectroscopy but to better atomic data. We show that to go further into the analyses of solar and stellar spectra, improvements are needed in the number and the accuracy of atomic data.
Published: 1994

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