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Now showing items 1 - 16 of 63

  • Mixed modes in red giants: a window on stellar evolution

    Mosser, B.   Benomar, O.   Belkacem, K.   Goupil, M. J.   Lagarde, N.   Michel, E.   Lebreton, Y.   Stello, D.   Vrard, M.   Barban, C.   Bedding, T. R.   Deheuvels, S.   Chaplin, W. J.   De Ridder, J.   Elsworth, Y.   Montalban, J.   Noels, A.   Ouazzani, R. M.   Samadi, R.   White, T. R.   Kjeldsen, H.  

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  • Impacts of radiative accelerations on solar-like oscillating main-sequence stars

    Deal, M.   Alecian, G.   Lebreton, Y.   Goupil, M. J.   Marques, J. P.   LeBlanc, F.   Morel, P.   Pichon, B.  

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  • How accurate are stellar ages based on stellar models?

    Lebreton, Y.   Goupil, M.J.   Montalbán, J.   Lebreton, Y.   Valls-Gabaud, D.   Charbonnel, C.  

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  • Asteroseismology for “à la carte” stellar age-dating and weighing

    Lebreton, Y.   Goupil, M. J.  

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  • Modelling a high-mass red giant observed by CoRoT

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

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  • Magnetic fields of intermediate-mass T Tauri stars

    Villebrun, F.   Alecian, E.   Hussain, G.   Bouvier, J.   Folsom, C. P.   Lebreton, Y.   Amard, L.   Charbonnel, C.   Gallet, F.   Haemmerlé, L.   Böhm, T.   Johns-Krull, C.   Kochukhov, O.   Marsden, S. C.   Morin, J.   Petit, P.  

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  • Impact of asteroseismology on improving stellar ages determination

    Lebreton, Y.   Alecian, G.   Lebreton, Y.   Richard, O.   Vauclair, G.  

    High precision photometry as performed by the CoRoT and Kepler satellites on-board instruments has allowed to detect stellar oscillations over the whole HR diagram. Oscillation frequencies are closely related to stellar interior properties via the density and sound speed profiles, themselves tightly linked with the mass and evolutionary state of stars. Seismic diagnostics performed on stellar internal structure models allow to infer the age and mass of oscillating stars. The accuracy and precision of the age determination depend both on the goodness of the observational parameters (seismic and classical) and on our ability to model a given star properly. They therefore suffer from any misunderstanding of the physical processes at work inside stars (as microscopic physics, transport processes ...). In this paper, we recall some seismic diagnostics of stellar age and we illustrate their efficiency in age-dating the CoRoT target HD 52265.
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  • Multiple Stellar Populations and Their Evolution in Globular Clusters: A Nucleosynthesis Perspective

    Charbonnel, C.   Moraux, E.   Lebreton, Y.   Charbonnel, C.  

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  • Excitation of stellar p-modes by turbulent convection

    Samadi, R.   Goupil, M.-J.   Lebreton, Y.  

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  • Seismology of δ Scuti stars in stellar clusters

    Lebreton, Y.   Michel, E.  

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  • MÉTHODE DE SUPPRESSION RÉVERSIBLE DE L'ODORAT CHEZ LA BREBIS ET VÉRIFICATION DE L'ANOSMIE AU MOYEN D'UNE ÉPREUVE COMPORTEMENTALE

    POINDRON, P.   LEBRETON, Y.   ORGEUR, P.   LAVENET, Colette  

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  • Spectra disentangling applied to the Hyades binary θ 2    Tauri AB: new orbit, orbital parallax and component properties

    Torres, K. B. V.   Lampens, P.   Frémat, Y.   Hensberge, H.   Lebreton, Y.   Škoda, P.  

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  • Gaia Data Release 2 Mapping the Milky Way disc kinematics

    Katz, D.   Antoja, T.   Romero-Gomez, M.   Drimmel, R.   Reyle, C.   Seabroke, G. M.   Soubiran, C.   Babusiaux, C.   Di Matteo, P.   Figueras, F.   Poggio, E.   Robin, A. C.   Evans, D. W.   Brown, A. G. A.   Vallenari, A.   Prusti, T.   de Bruijne, J. H. J.   Bailer-Jones, C. A. L.   Biermann, M.   Eyer, L.   Jansen, F.   Jordi, C.   Klioner, S. A.   Lammers, U.   Lindegren, L.   Luri, X.   Mignard, F.   Panem, C.   Pourbaix, D.   Randich, S.   Sartoretti, P.   Siddiqui, H. I.   van Leeuwen, F.   Walton, N. A.   Arenou, F.   Bastian, U.   Cropper, M.   Lattanzi, M. G.   Bakker, J.   Cacciari, C.   Castaneda, J.   Chaoul, L.   Cheek, N.   De Angeli, F.   Fabricius, C.   Guerra, R.   Holl, B.   Masana, E.   Messineo, R.   Mowlavi, N.   Nienartowicz, K.   Panuzzo, P.   Portell, J.   Riello, M.   Tanga, P.   Thevenin, F.   Gracia-Abril, G.   Comoretto, G.   Garcia-Reinaldos, M.   Teyssier, D.   Altmann, M.   Andrae, R.   Audard, M.   Bellas-Velidis, I.   Benson, K.   Berthier, J.   Blomme, R.   Burgess, P.   Busso, G.   Carry, B.   Cellino, A.   Clementini, G.   Clotet, M.   Creevey, O.   Davidson, M.   De Ridder, J.   Delchambre, L.   Dell'Oro, A.   Ducourant, C.   Fernandez-Hernandez, J.   Fouesneau, M.   Fremat, Y.   Galluccio, L.   Garcia-Torres, M.   Gonzalez-Nunez, J.   Gonzalez-Vidal, J. J.   Gosset, E.   Guy, L. P.   Halbwachs, J. -L.   Hambly, N. C.   Harrison, D. L.   Hernandez, J.   Hestroffer, D.   Hodgkin, S. T.   Hutton, A.   Jasniewicz, G.   Jean-Antoine-Piccolo, A.   Jordan, S.   Korn, A. J.   Krone-Martins, A.   Lanzafame, A. C.   Lebzelter, T.   Loeffler, W.   Manteiga, M.   Marrese, P. M.   Martin-Fleitas, J. M.   Moitinho, A.   Mora, A.   Muinonen, K.   Osinde, J.   Pancino, E.   Pauwels, T.   Petit, J. -M.   Recio-Blanco, A.   Richards, P. J.   Rimoldini, L.   Sarro, L. M.   Siopis, C.   Smith, M.   Sozzetti, A.   Sueveges, M.   Torra, J.   van Reeven, W.   Abbas, U.   Abreu Aramburu, A.   Accart, S.   Aerts, C.   Altavilla, G.   Alvarez, M. A.   Alvarez, R.   Alves, J.   Anderson, R. I.   Andrei, A. H.   Anglada Varela, E.   Antiche, E.   Arcay, B.   Astraatmadja, T. L.   Bach, N.   Baker, S. G.   Balaguer-Nunez, L.   Balm, P.   Barache, C.   Barata, C.   Barbato, D.   Barblan, F.   Barklem, P. S.   Barrado, D.   Barros, M.   Barstow, M. A.   Bartholome Munoz, S.   Bassilana, J. -L.   Becciani, U.   Bellazzini, M.   Berihuete, A.   Bertone, S.   Bianchi, L.   Bienayme, O.   Blanco-Cuaresma, S.   Boch, T.   Boeche, C.   Bombrun, A.   Borrachero, R.   Bossini, D.   Bouquillon, S.   Bourda, G.   Bragaglia, A.   Bramante, L.   Breddels, M. A.   Bressan, A.   Brouillet, N.   Bruesemeister, T.   Brugaletta, E.   Bucciarelli, B.   Burlacu, A.   Busonero, D.   Butkevich, A. G.   Buzzi, R.   Caffau, E.   Cancelliere, R.   Cannizzaro, G.   Cantat-Gaudin, T.   Carballo, R.   Carlucci, T.   Carrasco, J. M.   Casamiquela, L.   Castellani, M.   Castro-Ginard, A.   Charlot, P.   Chemin, L.   Chiavassa, A.   Cocozza, G.   Costigan, G.   Cowell, S.   Crifo, F.   Crosta, M.   Crowley, C.   Cuypers, J.   Dafonte, C.   Damerdji, Y.   Dapergolas, A.   David, P.   David, M.   de Laverny, P.   De Luise, F.   De March, R.   de Souza, R.   de Torres, A.   Debosscher, J.   del Pozo, E.   Delbo, M.   Delgado, A.   Delgado, H. E.   Diakite, S.   Diener, C.   Distefano, E.   Dolding, C.   Drazinos, P.   Duran, J.   Edvardsson, B.   Enke, H.   Eriksson, K.   Esquej, P.   Bontemps, G. Eynard   Fabre, C.   Fabrizio, M.   Faigler, S.   Falcao, A. J.   Farras Casas, M.   Federici, L.   Fedorets, G.   Fernique, P.   Filippi, F.   Findeisen, K.   Fonti, A.   Fraile, E.   Fraser, M.   Frezouls, B.   Gai, M.   Galleti, S.   Garabato, D.   Garcia-Sedano, F.   Garofalo, A.   Garralda, N.   Gavel, A.   Gavras, P.   Gerssen, J.   Geyer, R.   Giacobbe, P.   Gilmore, G.   Girona, S.   Giuffrida, G.   Glass, F.   Gomes, M.   Granvik, M.   Gueguen, A.   Guerrier, A.   Guiraud, J.   Gutierrez-Sanchez, R.   Haigron, R.   Hatzidimitriou, D.   Hauser, M.   Haywood, M.   Heiter, U.   Helmi, A.   Heu, J.   Hilger, T.   Hobbs, D.   Hofmann, W.   Holland, G.   Huckle, H. E.   Hypki, A.   Icardi, V.   Janssen, K.   de Fombelle, G. Jevardat   Jonker, P. G.   Juhasz, A. L.   Julbe, F.   Karampelas, A.   Kewley, A.   Klar, J.   Kochoska, A.   Kohley, R.   Kolenberg, K.   Kontizas, M.   Kontizas, E.   Koposov, S. E.   Kordopatis, G.   Kostrzewa-Rutkowska, Z.   Koubsky, P.   Lambert, S.   Lanza, A. F.   Lasne, Y.   Lavigne, J. -B.   Le Fustec, Y.   Le Poncin-Lafitte, C.   Lebreton, Y.   Leccia, S.   Leclerc, N.   Lecoeur-Taibi, I.   Lenhardt, H.   Leroux, F.   Liao, S.   Licata, E.   Lindstrom, H. E. P.   Lister, T. A.   Livanou, E.   Lobel, A.   Lopez, M.   Managau, S.   Mann, R. G.   Mantelet, G.   Marchal, O.   Marchant, J. M.   Marconi, M.   Marinoni, S.   Marschalko, G.   Marshall, D. J.   Martino, M.   Marton, G.   Mary, N.   Massari, D.   Matijevic, G.   Mazeh, T.   McMillan, P. J.   Messina, S.   Michalik, D.   Millar, N. R.   Molina, D.   Molinaro, R.   Molnar, L.   Montegriffo, P.   Mor, R.   Morbidelli, R.   Morel, T.   Morris, D.   Mulone, A. F.   Muraveva, T.   Musella, I.   Nelemans, G.   Nicastro, L.   Noval, L.   O'Mullane, W.   Ordenovic, C.   Ordonez-Blanco, D.   Osborne, P.   Pagani, C.   Pagano, I.   Pailler, F.   Palacin, H.   Palaversa, L.   Panahi, A.   Pawlak, M.   Piersimoni, A. M.   Pineau, F. -X.   Plachy, E.   Plum, G.   Poujoulet, E.   Prsa, A.   Pulone, L.   Racero, E.   Ragaini, S.   Rambaux, N.   Ramos-Lerate, M.   Regibo, S.   Riclet, F.   Ripepi, V.   Riva, A.   Rivard, A.   Rixon, G.   Roegiers, T.   Roelens, M.   Rowell, N.   Royer, F.   Ruiz-Dern, L.   Sadowski, G.   Selles, T. Sagrista   Sahlmann, J.   Salgado, J.   Salguero, E.   Sanna, N.   Santana-Ros, T.   Sarasso, M.   Savietto, H.   Schultheis, M.   Sciacca, E.   Segol, M.   Segovia, J. C.   Segransan, D.   Shih, I-C.   Siltala, L.   Silva, A. F.   Smart, R. L.   Smith, K. W.   Solano, E.   Solitro, F.   Sordo, R.   Soria Nieto, S.   Souchay, J.   Spagna, A.   Spoto, F.   Stampa, U.   Steele, I. A.   Steidelmueller, H.   Stephenson, C. A.   Stoev, H.   Suess, F. F.   Surdej, J.   Szabados, L.   Szegedi-Elek, E.   Tapiador, D.   Taris, F.   Tauran, G.   Taylor, M. B.   Teixeira, R.   Terrett, D.   Teyssandier, P.   Thuillot, W.   Titarenko, A.   Torra Clotet, F.   Turon, C.   Ulla, A.   Utrilla, E.   Uzzi, S.   Vaillant, M.   Valentini, G.   Valette, V.   van Elteren, A.   Van Hemelryck, E.   van Leeuwen, M.   Vaschetto, M.   Vecchiato, A.   Veljanoski, J.   Viala, Y.   Vicente, D.   Vogt, S.   von Essen, C.   Voss, H.   Votruba, V.   Voutsinas, S.   Walmsley, G.   Weiler, M.   Wertz, O.   Wevers, T.   Wyrzykowski, L.   Yoldas, A.   Zerjal, M.   Ziaeepour, H.   Zorec, J.   Zschocke, S.   Zucker, S.   Zurbach, C.   Zwitter, T.  

    Context. The second Gaia data release (Gaia DR2) contains high-precision positions, parallaxes, and proper motions for 1.3 billion sources as well as line-of-sight velocities for 7.2 million stars brighter than G(RVS) =3D 12 mag. Both samples provide a full sky coverage. Aims. To illustrate the potential of Gaia DR2, we provide a first look at the kinematics of the Milky Way disc, within a radius of several kiloparsecs around the Sun. Methods. We benefit for the first time from a sample of 6.4 million F-G-K stars with full 6D phase-space coordinates, precise parallaxes (sigma((omega) over bar)/(omega) over bar <=3D 20%), and precise Galactic cylindrical velocities (median uncertainties of 0.9-1.4 km s(-1) and 20% of the stars with uncertainties smaller than 1 km s(-1) on all three components). From this sample, we extracted a sub-sample of 3.2 million giant stars to map the velocity field of the Galactic disc from similar to 5 kpc to similar to 13 kpc from the Galactic centre and up to 2 kpc above and below the plane. We also study the distribution of 0.3 million solar neighbourhood stars (r < 200 pc), with median velocity uncertainties of 0.4 km s(-1), in velocity space and use the full sample to examine how the over-densities evolve in more distant regions. Results. Gaia DR2 allows us to draw 3D maps of the Galactocentric median velocities and velocity dispersions with unprecedented accuracy, precision, and spatial resolution. The maps show the complexity and richness of the velocity field of the galactic disc. We observe streaming motions in all the components of the velocities as well as patterns in the velocity dispersions. For example, we confirm the previously reported negative and positive galactocentric radial velocity gradients in the inner and outer disc, respectively. Here, we see them as part of a non-axisymmetric kinematic oscillation, and we map its azimuthal and vertical behaviour. We also witness a new global arrangement of stars in the velocity plane of the solar neighbourhood and in distant regions in which stars are organised in thin substructures with the shape of circular arches that are oriented approximately along the horizontal direction in the U - V plane. Moreover, in distant regions, we see variations in the velocity substructures more clearly than ever before, in particular, variations in the velocity of the Hercules stream. Conclusions. Gaia DR2 provides the largest existing full 6D phase-space coordinates catalogue. It also vastly increases the number of available distances and transverse velocities with respect to Gaia DR1. Gaia DR2 offers a great wealth of information on the Milky Way and reveals clear non-axisymmetric kinematic signatures within the Galactic disc, for instance. It is now up to the astronomical community to explore its full potential.
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  • Preparing the COROT space mission: new variable stars in the Galactic anticenter direction

    Poretti, E.   Alonso, R.   Amado, P.J.   Belmonte, J.A.   Garrido, R.   Martin-Ruiz, S.   Uytterhoeven, K.   Catala, C.   Lebreton, Y.   Michel, E.   Suarez, J.C.   Aerts, C.   Creevey, O.   Goupil, M.J.   Mantegazza, L.   Mathias, P.   Rainer, M.   Weiss, W.W.  

    The activities related to the preparation of the asteroseismic, photometric space mission COROT are described. Photoelectric observations, wide-field CCD photometry, uvbybeta calibrations, and further time series have been obtained at different observatories and telescopes. They have been planned to complete the COROT program in the direction of the Galactic anticenter. In addition to suitable asteroseismic targets covering the different evolutionary stages between zero-age main sequence and terminal-age main sequence, we discovered several other variable stars, both pulsating and geometric. We compared results on the incidence of variability in the Galactic center and anticenter directions. Physical parameters have been obtained, and evolutionary tracks fitting them have been calculated. The peculiarities of some individual stars are pointed out
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  • Properties of 42 solar-type kepler targets from the asteroseismic modeling portal

    Metcalfe, T.S.   Creevey, O.L.   Dogan, G.   Mathur, S.   Xu, H.   Bedding, T.R.   Chaplin, W.J.   Christensen-Dalsgaard, J.   Karoff, C.   Trampedach, R.   Benomar, O.   Brown, B.P.   Buzasi, D.L.   Campante, T.L.   Celik, Z.   Cunha, M.S.   Davies, G.R.   Deheuvels, S.   Derekas, A.   Di Mauro, M.P.   Garcia, R.A.   Guzik, J.A.   Howe, R.   MacGregor, K.B.   Mazumdar, A.   Montalban, J.   Monteiro, M.J.P.F.G.   Salabert, D.   Serenelli, A.   Stello, D.   Steslicki, M.   Suran, M.D.   Yinodotldinodotz, M.   Aksoy, C.   Elsworth, Y.   Gruberbauer, M.   Guenther, D.B.   Lebreton, Y.   Molaverdikhani, K.   Pricopi, D.   Simoniello, R.   White, T.R.  

    Recently the number of main-sequence and subgiant stars exhibiting solar-like oscillations that are resolved into individual mode frequencies has increased dramatically. While only a few such data sets were available for detailed modeling just a decade ago, the Kepler mission has produced suitable observations for hundreds of new targets. This rapid expansion in observational capacity has been accompanied by a shift in analysis and modeling strategies to yield uniform sets of derived stellar properties more quickly and easily. We use previously published asteroseismic and spectroscopic data sets to provide a uniform analysis of 42 solar-type Kepler targets from the Asteroseismic Modeling Portal. We find that fitting the individual frequencies typically doubles the precision of the asteroseismic radius, mass, and age compared to grid-based modeling of the global oscillation properties, and improves the precision of the radius and mass by about a factor of three over empirical scaling relations. We demonstrate the utility of the derived properties with several applications.
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  • THE EVOLUTION OF OXYGEN IN GALAXIES

    Stasinska, G.   Prantzos, N.   Meynet, G.   Simon-Diaz, S.   Chiappini, C.   Dessauges-Zavadsky, M.   Charbonnel, C.   Ludwig, H. -G.   Mendoza, C.   Grevesse, N.   Arnould, M.   Barbuy, B.   Lebreton, Y.   Decourchelle, A.   Hill, V.   Ferrando, P.   Hebrard, G.   Durret, F.   Katsuma, M.   Zeippen, C. J.  

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