Author: "J. P. Berger" - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"J. P. Berger"' showing total 121 results

Start Over Author "J. P. Berger"

121 results on '"J. P. Berger"'

1. First VLTI/GRAVITY Observations of HIP 65426 b: Evidence for a Low or Moderate Orbital Eccentricity

Author: Sarah Blunt, W. O. Balmer, J. J. Wang, S. Lacour, S. Petrus, G. Bourdarot, J. Kammerer, N. Pourré, E. Rickman, J. Shangguan, T. Winterhalder, R. Abuter, A. Amorim, R. Asensio-Torres, M. Benisty, J.-P. Berger, H. Beust, A. Boccaletti, A. Bohn, M. Bonnefoy, H. Bonnet, W. Brandner, F. Cantalloube, P. Caselli, B. Charnay, G. Chauvin, A. Chavez, E. Choquet, V. Christiaens, Y. Clénet, V. Coudé du Foresto, A. Cridland, R. Dembet, A. Drescher, and G. Duvert
Subjects: Astronomy
Abstract: Giant exoplanets have been directly imaged over orders of magnitude of orbital separations, prompting theoretical and observational investigations of their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data of HIP 65426 b, a cold, giant exoplanet which is a particular challenge for most formation theories at a projected separation of 92 au from its primary. Leveraging GRAVITY's astrometric precision, we present an updated eccentricity posterior that disfavors large eccentricities. The eccentricity posterior is still prior dependent, and we extensively interpret and discuss the limits of the posterior constraints presented here. We also perform updated spectral comparisons with self-consistent forward-modeled spectra, finding a best-fit ExoREM model with solar metallicity and C/O = 0.6. An important caveat is that it is difficult to estimate robust errors on these values, which are subject to interpolation errors as well as potentially missing model physics. Taken together, the orbital and atmospheric constraints paint a preliminary picture of formation inconsistent with scattering after disk dispersal. Further work is needed to validate this interpretation. Analysis code used to perform this work is available on GitHub: https://github.com/sblunt/hip65426.
Published: 2023
Full Text: View/download PDF

2. VLTI/GRAVITY Provides Evidence the Young, Substellar Companion HD 136164 Ab Formed Like a 'Failed Star'

Author: William O. Balmer, L. Pueyo, S. Lacour, J. J. Wang, T. Stolker, J. Kammerer, N. Pourré, M. Nowak, E. Rickman, S. Blunt, A. Sivaramakrishnan, D. Sing, K. Wagner, G.-D. Marleau, A.-M. Lagrange, R. Abuter, A. Amorim, R. Asensio-Torres, J.-P. Berger, H. Beust, A. Boccaletti, A. Bohn, M. Bonnefoy, H. Bonnet, M. S. Bordoni, G. Bourdarot, W. Brandner, F. Cantalloube, P. Caselli, B. Charnay, G. Chauvin, A. Chavez, E. Choquet, V. Christiaens, Y. Clénet, V. Coudé du Foresto, A. Cridland, R. Davies, R. Dembet, A. Drescher, G. Duvert, A. Eckart, F. Eisenhauer, N. M. Förster Schreiber, P. Garcia, R. Garcia Lopez, E. Gendron, R. Genzel, S. Gillessen, J. H. Girard, S. Grant, X. Haubois, G. Heißel, Th. Henning, S. Hinkley, S. Hippler, M. Houllé, Z. Hubert, L. Jocou, M. Keppler, P. Kervella, L. Kreidberg, N. T. Kurtovic, V. Lapeyrère, J.-B. Le Bouquin, P. Léna, D. Lutz, A.-L. Maire, F. Mang, A. Mérand, P. Mollière, C. Mordasini, D. Mouillet, E. Nasedkin, T. Ott, G. P. P. L. Otten, C. Paladini, T. Paumard, K. Perraut, G. Perrin, O. Pfuhl, D. C. Ribeiro, L. Rodet, Z. Rustamkulov, J. Shangguan, T. Shimizu, C. Straubmeier, E. Sturm, L. J. Tacconi, A. Vigan, F. Vincent, K. Ward-Duong, F. Widmann, T. Winterhalder, J. Woillez, S. Yazici, and the GRAVITY Collaboration
Subjects: Brown dwarfs, Substellar companion stars, Orbit determination, Orbits, Astronomy, QB1-991
Abstract: Young, low-mass brown dwarfs orbiting early-type stars, with low mass ratios ( q ≲ 0.01), appear to be intrinsically rare and present a formation dilemma: could a handful of these objects be the highest-mass outcomes of “planetary” formation channels (bottom up within a protoplanetary disk), or are they more representative of the lowest-mass “failed binaries” (formed via disk fragmentation or core fragmentation)? Additionally, their orbits can yield model-independent dynamical masses, and when paired with wide wavelength coverage and accurate system age estimates, can constrain evolutionary models in a regime where the models have a wide dispersion depending on the initial conditions. We present new interferometric observations of the 16 Myr substellar companion HD 136164 Ab (HIP 75056 Ab) made with the Very Large Telescope Interferometer (VLTI)/GRAVITY and an updated orbit fit including proper motion measurements from the Hipparcos–Gaia Catalog of Accelerations. We estimate a dynamical mass of 35 ± 10 M _J ( q ∼ 0.02), making HD 136164 Ab the youngest substellar companion with a dynamical mass estimate. The new mass and newly constrained orbital eccentricity ( e = 0.44 ± 0.03) and separation (22.5 ± 1 au) could indicate that the companion formed via the low-mass tail of the initial mass function. Our atmospheric fit to a SPHINX M-dwarf model grid suggests a subsolar C/O ratio of 0.45 and 3 × solar metallicity, which could indicate formation in a circumstellar disk via disk fragmentation. Either way, the revised mass estimate likely excludes bottom-up formation via core accretion in a circumstellar disk. HD 136164 Ab joins a select group of young substellar objects with dynamical mass estimates; epoch astrometry from future Gaia data releases will constrain the dynamical mass of this crucial object further.
Published: 2024
Full Text: View/download PDF

3. VLTI/GRAVITY Observations and Characterization of the Brown Dwarf Companion HD 72946 B

Author: William O. Balmer, Laurent Pueyo, Tomas Stolker, Henrique Reggiani, A.-L. Maire, S. Lacour, P. Mollière, M. Nowak, D. Sing, N. Pourré, S. Blunt, J. J. Wang, E. Rickman, J. Kammerer, Th. Henning, K. Ward-Duong, R. Abuter, A. Amorim, R. Asensio-Torres, M. Benisty, J.-P. Berger, H. Beust, A. Boccaletti, A. Bohn, M. Bonnefoy, H. Bonnet, G. Bourdarot, W. Brandner, F. Cantalloube, P. Caselli, B. Charnay, G. Chauvin, A. Chavez, E. Choquet, V. Christiaens, Y. Clénet, V. Coudé du Foresto, A. Cridland, R. Dembet, J. Dexter, A. Drescher, G. Duvert, A. Eckart, F. Eisenhauer, F. Gao, P. Garcia, R. Garcia Lopez, E. Gendron, R. Genzel, S. Gillessen, J. H. Girard, X. Haubois, G. Heißel, S. Hinkley, S. Hippler, M. Horrobin, M. Houllé, Z. Hubert, L. Jocou, M. Keppler, P. Kervella, L. Kreidberg, A.-M. Lagrange, V. Lapeyrère, J.-B. Le Bouquin, P. Léna, D. Lutz, J. D. Monnier, D. Mouillet, E. Nasedkin, T. Ott, G. P. P. L. Otten, C. Paladini, T. Paumard, K. Perraut, G. Perrin, O. Pfuhl, J. Rameau, L. Rodet, G. Rousset, Z. Rustamkulov, J. Shangguan, T. Shimizu, J. Stadler, O. Straub, C. Straubmeier, E. Sturm, L. J. Tacconi, E. F. van Dishoeck, A. Vigan, F. Vincent, S. D. von Fellenberg, F. Widmann, E. Wieprecht, E. Wiezorrek, T. Winterhalder, J. Woillez, S. Yazici, A. Young, The ExoGRAVITY Collaboration, and The GRAVITY Collaboration
Subjects: Brown dwarfs, L dwarfs, Interferometry, Long baseline interferometry, Optical interferometry, Orbit determination, Astrophysics, QB460-466
Abstract: Tension remains between the observed and modeled properties of substellar objects, but objects in binary orbits, with known dynamical masses, can provide a way forward. HD 72946 B is a recently imaged brown dwarf companion to a nearby, solar-type star. We achieve ∼100 μ as relative astrometry of HD 72946 B in the K band using VLTI/GRAVITY, unprecedented for a benchmark brown dwarf. We fit an ensemble of measurements of the orbit using orbitize! and derive a strong dynamical mass constraint M _B = 69.5 ± 0.5 M _Jup assuming a strong prior on the host star mass M _A = 0.97 ± 0.01 M _⊙ from an updated stellar analysis. We fit the spectrum of the companion to a grid of self-consistent BT-Settl-CIFIST model atmospheres, and perform atmospheric retrievals using petitRADTRANS . A dynamical mass prior only marginally influences the sampled distribution of effective temperature, but has a large influence on the surface gravity and radius, as expected. The dynamical mass alone does not strongly influence retrieved pressure–temperature or cloud parameters within our current retrieval setup. Independently of the cloud prescription and prior assumptions, we find agreement within ±2 σ between the C/O of the host (0.52 ± 0.05) and brown dwarf (0.43–0.63), as expected from a molecular cloud collapse formation scenario, but our retrieved metallicities are implausibly high (0.6–0.8) in light of the excellent agreement of the data with the solar-abundance model grid. Future work on our retrieval framework will seek to resolve this tension. Additional study of low surface gravity objects is necessary to assess the influence of a dynamical mass prior on atmospheric analysis.
Published: 2023
Full Text: View/download PDF

4. Constraining particle acceleration in Sgr A? with simultaneous GRAVITY, Spitzer, NuSTAR, and Chandra observations

Author: R. Abuter, A. Amorim, M. Bauböck, F. Baganoff, J. P. Berger, H. Boyce, H. Bonnet, W. Brandner, Y. Clénet, R. Davies, P. T. de Zeeuw, J. Dexter, Y. Dallilar, A. Drescher, A. Eckart, F. Eisenhauer, G. G. Fazio, N. M. Förster Schreiber, K. Foster, C. Gammie, P. Garcia, F. Gao, E. Gendron, R. Genzel, G. Ghisellini, S. Gillessen, M. A. Gurwell, M. Habibi, D. Haggard, C. Hailey, F. A. Harrison, X. Haubois, G. Heißel, T. Henning, and S. Hippler
Subjects: Astrophysics
Abstract: We report the time-resolved spectral analysis of a bright near-infrared and moderate X-ray flare of Sgr A⋆. We obtained light curves in the M, K, and H bands in the mid- and near-infrared and in the 2 − 8 keV and 2 − 70 keV bands in the X-ray. The observed spectral slope in the near-infrared band is νLν ∝ ν0.5 ± 0.2; the spectral slope observed in the X-ray band is νLν ∝ ν−0.7 ± 0.5. Using a fast numerical implementation of a synchrotron sphere with a constant radius, magnetic field, and electron density (i.e., a one-zone model), we tested various synchrotron and synchrotron self-Compton scenarios. The observed near-infrared brightness and X-ray faintness, together with the observed spectral slopes, pose challenges for all models explored. We rule out a scenario in which the near-infrared emission is synchrotron emission and the X-ray emission is synchrotron self-Compton. Two realizations of the one-zone model can explain the observed flare and its temporal correlation: one-zone model in which the near-infrared and X-ray luminosity are produced by synchrotron self-Compton and a model in which the luminosity stems from a cooled synchrotron spectrum. Both models can describe the mean spectral energy distribution (SED) and temporal evolution similarly well. In order to describe the mean SED, both models require specific values of the maximum Lorentz factor γmax, which differ by roughly two orders of magnitude. The synchrotron self-Compton model suggests that electrons are accelerated to γmax ∼ 500, while cooled synchrotron model requires acceleration up to γmax ∼ 5 × 104. The synchrotron self-Compton scenario requires electron densities of 1010 cm−3 that are much larger than typical ambient densities in the accretion flow. Furthermore, it requires a variation of the particle density that is inconsistent with the average mass-flow rate inferred from polarization measurements and can therefore only be realized in an extraordinary accretion event. In contrast, assuming a source size of 1 RS, the cooled synchrotron scenario can be realized with densities and magnetic fields comparable with the ambient accretion flow. For both models, the temporal evolution is regulated through the maximum acceleration factor γmax, implying that sustained particle acceleration is required to explain at least a part of the temporal evolution of the flare.
Published: 2021
Full Text: View/download PDF

5. The mass of β Pictoris c from β Pictoris b orbital motion

Author: Matthias Samland, Anne-Lise Maire, David Mouillet, Andreas Eckart, Valentin Christiaens, Julien Woillez, Sarah Blunt, K. Perraut, T. Paumard, T. Ott, Myriam Benisty, E. Nasedkin, A. Mérand, Z. Hubert, Stefan Hippler, Frank Eisenhauer, Roderick Dembet, Gilles Otten, F. H. Vincent, Pierre Léna, Jinyi Shangguan, Miriam Keppler, Ekkehard Wieprecht, G. Bourdarot, M. Houllé, Odele Straub, Alexander J. Bohn, M. Nowak, Felix Widmann, K. Ward-Duong, P. T. de Zeeuw, J.-B. Le Bouquin, Julia Stadler, T. Taro Shimizu, A. Boccaletti, David K. Sing, Ji Wang, Linda J. Tacconi, Arthur Vigan, Elodie Choquet, Jens Kammerer, Claudia Paladini, J. Rameau, R. J. García López, Xavier Haubois, E. Rickman, Guy Perrin, J. P. Berger, Wolfgang Brandner, Eric Gendron, G. Heißel, H. Bonnet, Laurent Jocou, A. Cridland, S. D. von Fellenberg, Pierre Kervella, R. Asensio-Torres, G. Rousset, O. Pfuhl, Erich Wiezorrek, M. Bonnefoy, Y. Clénet, Senol Yazici, R. Abuter, John D. Monnier, Laura Kreidberg, Paulo J. V. Garcia, Zafar Rustamkulov, Tomas Stolker, Gilles Duvert, Paul Mollière, H. Beust, Eckhard Sturm, António Amorim, Anne-Marie Lagrange, Paola Caselli, Christian Straubmeier, Th. Henning, G. Chauvin, Benjamin Charnay, Sylvestre Lacour, E. F. van Dishoeck, Jason Dexter, Stefan Gillessen, André Young, D. Lutz, V. Coudé du Foresto, R. Genzel, Feng Gao, J. H. Girard, Faustine Cantalloube, L. Rodet, Sasha Hinkley, A. Drescher, Vincent Lapeyrere, Laurent Pueyo, Matthew Horrobin, M. L. Bolzer, Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), MacoPharma, 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Caltech Department of Astronomy [Pasadena], California Institute of Technology (CALTECH), Departamento de Astronomía, Universidad de Chile = University of Chile [Santiago] (UCHILE), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, European Southern Observatory (ESO), Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Max-Planck-Institut für Astronomie (MPIA), 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), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Service de Pathologie respiratoire et allergologie [CHU Limoges], CHU Limoges, University of Auckland [Auckland], the GRAVITY Collaboration, Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), 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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), 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), Harvard University-Smithsonian Institution, and Université de Genève = University of Geneva (UNIGE)
Subjects: Astrophysics - instrumentation and methods for astrophysics, planets and satellites: detection, 010504 meteorology & atmospheric sciences, Astrophysics, Astrophysics - Earth and planetary astrophysics, 01 natural sciences, High angular resolution, Planet, instrumentation: high angular resolution, 0103 physical sciences, Beta Pictoris, 10. No inequality, instrumentation: interferometers, 010303 astronomy & astrophysics, Instrumentation, 0105 earth and related environmental sciences, Orbital elements, Physics, Interferometers, Astronomy and Astrophysics, Astrometry, Exoplanet, Radial velocity, Detection, Space and Planetary Science, Orbital motion, Planets and satellites, Eccentricity (mathematics), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Aims.We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet.Methods.We combined previous astrometry ofβPictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion ofβPictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet,βPictoris c, was also reobserved at a separation of 96 mas, confirming the previous orbital estimations.Results.From the astrometry of planet b only, we can (i) detect the presence ofβPictoris c and (ii) constrain its mass to 10.04−3.10+4.53MJup. If one adds the astrometry ofβPictoris c, the mass is narrowed down to 9.15−1.06+1.08MJup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89−0.75+0.75MJup. With a semimajor axis of 2.68 ± 0.02 au, a period of 1221 ± 15 days, and an eccentricity of 0.32 ± 0.02, the orbital parameters ofβPictoris c are now constrained as precisely as those ofβPictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets’ dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet.
Published: 2021
Full Text: View/download PDF

6. High Angular Resolution and Young Stellar Objects: Imaging the Surroundings of MWC 158 by Optical Interferometry

Author: J. Kluska, F. Malbet, J.-P. Berger, M. Benisty, B. Lazareff, J.-B. Le Bouquin, and C. Pinte
Published: 2020
Full Text: View/download PDF

7. The GRAVITY young stellar object survey

Author: A. Caratti o Garatti, R. Fedriani, R. Garcia Lopez, M. Koutoulaki, K. Perraut, H. Linz, W. Brandner, P. Garcia, L. Klarmann, T. Henning, L. Labadie, J. Sanchez-Bermudez, B. Lazareff, E. F. van Dishoeck, P. Caselli, P. T. de Zeeuw, A. Bik, M. Benisty, C. Dougados, T. P. Ray, A. Amorim, J.-P. Berger, Y. Clénet, V. Coudé du Foresto, G. Duvert, A. Eckart, F. Eisenhauer, F. Gao, E. Gendron, and R. Genzel
Published: 2020
Full Text: View/download PDF

8. Investigating the magnetospheric accretion process in the young pre-transitional disk system DoAr 44 (V2062 Oph)

Author: J. Bouvier, E. Alecian, S. H. P. Alencar, A. Sousa, J.-F. Donati, K. Perraut, A. Bayo, L. M. Rebull, C. Dougados, G. Duvert, J.-P. Berger, M. Benisty, K. Pouilly, C. Folsom, C. Moutou
Published: 2020
Full Text: View/download PDF

9. A family portrait of disk inner rims around Herbig Ae/Be stars

Author: J. Kluska, J.-P. Berger, F. Malbet, B. Lazareff, M. Benisty, J.-B. Le Bouquin, O. Absil, F. Baron, A. Delboulbé, G. Duvert, A. Isella, L. Jocou, A. Juhasz, S. Kraus, R. Lachaume, F. Ménard, R. Millan-Gabet, J. D. Monnier, T. Moulin, K. Perraut, S. Rochat, C. Pinte, F. Soulez, M. Tallon, W.-F. Thi, E. Thiébaut, W. Traub, G. Zins
Published: 2020
Full Text: View/download PDF

10. The GRAVITY young stellar object survey

Author: Y.-I. Bouarour, K. Perraut, F. Ménard, W. Brandner, A. Caratti o Garatti, P. Caselli, E. van Dishoeck, C. Dougados, R. Garcia-Lopez, R. Grellmann, T. Henning, L. Klarmann, L. Labadie, A. Natta, J. Sanchez-Bermudez, W.-F. Thi, P. T. de Zeeuw, A. Amorim, M. Bauböck, M. Benisty, J.-P. Berger, Y. Clenet, V. Coudé du Foresto, G. Duvert, A. Eckart, F. Eisenhauer, F. Eupen, M. Filho, F. Gao, P. Garcia
Published: 2020
Full Text: View/download PDF

11. NAOMI: the adaptive optics system of the Auxiliary Telescopes of the VLTI

Author: E. Cottalorda, C. Heritier, F. Delplancke-Ströbele, S. Zúñiga-Fernández, S. Guieu, Javier Reyes, M. Seidel, Alexander Meister, Laurent Jocou, Johan Kosmalski, G. Santos Tomás, Oliver Pfuhl, Pierre Bourget, Marcos Suarez, Christophe Verinaud, J. L. Beuzit, Anthony Meilland, Philippe B. Gitton, Andreas Haimerl, J.-B. Le Bouquin, Eric Stadler, C. Frank, Christophe Dupuy, Lorenzo Pettazzi, Pascaline Darré, Xavier Haubois, Gérard Zins, Frédéric Gonté, Jaime Alonso, Bruno Lopez, R. Donaldson, Peter Krempl, H. Bonnet, Pavel Shchekaturov, Johann Kolb, Frank Eisenhauer, Pablo Gutierrez, Thibaut Guerlet, Paul Lilley, Julien Woillez, J. P. Berger, Gerhard Fischer, M. Todorovic, Sebastien Egner, A. Mérand, Thibaut Moulin, Luis Caniguante, Christian Stephan, J. P. Kirchbauer, Luigi Andolfato, Guillermo Valdes, N. Hubin, D. Phan, Eloy Fuenteseca, Stewart McLay, M. Riedel, Isabelle Percheron, A. Delboulbe, Jerome Paufique, W. Pirani, Christian Schmid, Christian Soenke, J. Dupeyron, Jose Abad, Andrew Rakich, M. Le Louarn, Pablo Barriga, Stefan Huber, P. Haguenauer, Paul Jolley, G. Bourdarot, E. Aller Carpentier, R. Brast, Nicolas Schuhler, B. Delabre, Reinhold J. Dorn, Roderick Dembet, Sylvain Rochat, Roberto Abuter, Yves Magnard, J. Quentin, Luca Pasquini, R. Ridings, European Southern Observatory (ESO), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre Spatial Universitaire de Grenoble ( CSUG), CRLCC Eugène Marquis (CRLCC), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and 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)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Wavefront, Coupling, Very Large Telescope, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Context (language use), Astrophysics, Tracking (particle physics), 01 natural sciences, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 010309 optics, Interferometry, Optics, Space and Planetary Science, 0103 physical sciences, Astronomical seeing, Astrophysics::Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, business, Adaptive optics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics
Abstract: The tip-tilt stabilisation system of the 1.8 m Auxiliary Telescopes of the Very Large Telescope Interferometer was never dimensioned for robust fringe tracking, except when atmospheric seeing conditions are excellent. Increasing the level of wavefront correction at the telescopes is expected to improve the coupling into the single-mode fibres of the instruments, and enable robust fringe tracking even in degraded conditions. We deployed a new adaptive optics module for interferometry (NAOMI) on the Auxiliary Telescopes. We present its design, performance, and effect on the observations that are carried out with the interferometric instruments., Comment: 10 pages, 18 figures, 2 tables, A&A forthcoming
Published: 2019
Full Text: View/download PDF

12. First direct detection of an exoplanet by optical interferometry

Author: S. Lacour, M. Nowak, J. Wang, O. Pfuhl, F. Eisenhauer, R. Abuter, A. Amorim, N. Anugu, M. Benisty, J. P. Berger, H. Beust, N. Blind, M. Bonnefoy, H. Bonnet, P. Bourget, W. Brandner, A. Buron, C. Collin, B. Charnay, F. Chapron, Y. Clénet, V. Coudé du Foresto, P. T. de Zeeuw, C. Deen, R. Dembet, J. Dexter, G. Duvert, A. Eckart, N. M. Förster Schreiber, P. Fédou, P. Garcia, R. Garcia Lopez, and F. Ga
Published: 2019
Full Text: View/download PDF

13. A three-telescope active integrated optics spectro-interferometric combiner in the L-band for application to high precision interferometry

Author: Nadège Courjal, J. P. Berger, I. Heras, Gwenn Ulliac, S. Heidmann, Guillermo Martin, Alain Morand, E. Le Coarer, P. Benech, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut de Microélectronique, Electromagnétisme et Photonique - Laboratoire d'Hyperfréquences et Caractérisation (IMEP-LAHC ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), 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)-Centre National de la Recherche Scientifique (CNRS), Institut de Microélectronique, Electromagnétisme et Photonique - Laboratoire d'Hyperfréquences et Caractérisation (IMEP-LAHC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), and Université de Franche-Comté (UFC)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Technologie de Belfort-Montbeliard (UTBM)
Subjects: Physics, L band, business.industry, 02 engineering and technology, 01 natural sciences, law.invention, 010309 optics, Telescope, Interferometry, 020210 optoelectronics & photonics, Optics, law, 0103 physical sciences, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, 0202 electrical engineering, electronic engineering, information engineering, Integrated optics, business, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2018
Full Text: View/download PDF

14. GRAVITY chromatic imaging of η Car's core. Milliarcsecond resolution imaging of the wind-wind collision zone (Brγ, He I)

Author: S. Kellner, Pierre Kervella, Faustine Cantalloube, Johana Panduro, Magdalena Lippa, V. Coudé du Foresto, Y. Clénet, R. Abuter, G. Avila, Matteo Accardo, Konrad R. W. Tristram, Dan Popovic, Alejandra Rosales, A. Buron, R. Genzel, C. Deen, Laurent Jocou, Markus Schöller, T. Ott, H. Bonnet, P. Fédou, Frank Eisenhauer, R. van Boekel, Stefan Hippler, André Müller, Pierre Léna, Thibaut Moulin, Julien Woillez, L. Pallanca, Ekkehard Wieprecht, P.-O. Petrucci, N. Hubin, Leander Mehrgan, Sylvestre Lacour, Markus Wittkowski, Vincent Lapeyrere, Christian A. Hummel, M. Haug, Eckhard Sturm, Frederic Derie, Thanh Phan Duc, Sarah Kendrew, Burkhard Wolff, Mario Kiekebusch, Nicolas Blind, Andreas Kaufer, W. J. de Wit, Feng Gao, C. Collin, Silvia Scheithauer, L. Kern, Roderick Dembet, Matthew Horrobin, J.-U. Pott, Stefan Gillessen, Johann Kolb, Narsireddy Anugu, R.-R. Rohloff, M. Riquelme, J. Sanchez-Bermudez, Andreas Eckart, J. Moreno-Ventas, R. Brast, Z. Hubert, Isabelle Percheron, M. Mellein, F. Delplancke-Ströbele, M. Karl, Udo Neumann, Imke Wank, Rainer Lenzen, Odele Straub, Michael Esselborn, Armin Huber, J.-B. Le Bouquin, Ralf Klein, Juan-Luis Ramos, Erich Wiezorrek, Samuel Lévêque, K. Perraut, Frédéric Cassaing, C. E. Garcia Dabo, F. Müller, P. M. Plewa, Ewald Müller, N. Ventura, F. Chapron, Gerd Weigelt, M. Ebert, Martin Kulas, M. Wiest, Elodie Choquet, Luca Pasquini, A. Caratti o Garatti, A. Pflüger, T. de Zeeuw, Guy Perrin, Myriam Benisty, Yves Magnard, Joachim M. Bestenlehner, S. Oberti, António Amorim, Nicolas Schuhler, B. Lazareff, Paulo J. V. Garcia, Jason Dexter, Christian Straubmeier, Th. Henning, Jason Spyromilio, F. H. Vincent, A. Mérand, Senol Yazici, Felix Widmann, C. Rau, Pierre Bourget, R. J. García López, Xavier Haubois, Eric Gendron, Gérard Zins, G. Rousset, Andres J. Ramirez, Gilles Duvert, T. Paumard, Lieselotte Jochum, Idel Waisberg, F. Haussmann, O. Pfuhl, Sebastian Rabien, G. Rodríguez-Coira, Gerd Jakob, J. P. Berger, Wolfgang Brandner, D. Ziegler, and Marcos Suarez
Subjects: Physics, 010308 nuclear & particles physics, Binary number, Astronomy and Astrophysics, Astrophysics, Collision, 01 natural sciences, Galaxy, Wavelength, 13. Climate action, Space and Planetary Science, Angular diameter, 0103 physical sciences, Radiative transfer, Chromatic scale, 010303 astronomy & astrophysics, Cavity wall
Abstract: Context. η Car is one of the most intriguing luminous blue variables in the Galaxy. Observations and models of the X-ray, ultraviolet, optical, and infrared emission suggest a central binary in a highly eccentric orbit with a 5.54 yr period residing in its core. 2D and 3D radiative transfer and hydrodynamic simulations predict a primary with a dense and slow stellar wind that interacts with the faster and lower density wind of the secondary. The wind-wind collision scenario suggests that the secondary’s wind penetrates the primary’s wind creating a low-density cavity in it, with dense walls where the two winds interact. However, the morphology of the cavity and its physical properties are not yet fully constrained. Aims. We aim to trace the inner ∼5–50 au structure of η Car’s wind-wind interaction, as seen through Brγ and, for the first time, through the He I 2s-2p line. Methods. We have used spectro-interferometric observations with the K-band beam-combiner GRAVITY at the VLTI. The analyses of the data include (i) parametrical model-fitting to the interferometric observables, (ii) a CMFGEN model of the source’s spectrum, and (iii) interferometric image reconstruction. Results. Our geometrical modeling of the continuum data allows us to estimate its FWHM angular size close to 2 mas and an elongation ratio ϵ = 1.06 ± 0.05 over a PA = 130° ± 20°. Our CMFGEN modeling of the spectrum helped us to confirm that the role of the secondary should be taken into account to properly reproduce the observed Brγ and He I lines. Chromatic images across the Brγ line reveal a southeast arc-like feature, possibly associated to the hot post-shocked winds flowing along the cavity wall. The images of the He I 2s-2p line served to constrain the 20 mas (∼50 au) structure of the line-emitting region. The observed morphology of He I suggests that the secondary is responsible for the ionized material that produces the line profile. Both the Brγ and the He I 2s-2p maps are consistent with previous hydrodynamical models of the colliding wind scenario. Future dedicated simulations together with an extensive interferometric campaign are necessary to refine our constraints on the wind and stellar parameters of the binary, which finally will help us predict the evolutionary path of η Car.
Published: 2018

15. Cancer cell invasion and EMT marker expression: a three-dimensional study of the human cancer-host interface

Author: Peter Bronsert, Tobias Keck, D Bausch, M Kuehs, Ulrich F. Wellner, Gian Kayser, Elmar Stickeler, Ulrich T. Hopt, Oliver Schilling, Agnes Csanadi, Kathrin Enderle-Ammour, Martin Werner, CP Reiss, Johannes Lotz, J. P. Berger, Sylvia Timme, Y Vashist, Thomas Brabletz, Moritz Bader, Bernward Passlick, Jens Hoeppner, Janine Olesch, and Ilona Kohler
Subjects: Budding, Pathology, medicine.medical_specialty, Transition (genetics), Cell migration, Breast Adenocarcinoma, Biology, Pathology and Forensic Medicine, Staining, Cancer cell, Gene expression, Cancer research, medicine, Human cancer
Abstract: Cancer cell invasion takes place at the cancer-host interface and is a prerequisite for distant metastasis. The relationships between current biological and clinical concepts such as cell migration modes, tumour budding and epithelial-mesenchymal transition (EMT) remains unclear in several aspects, especially for the 'real' situation in human cancer. We developed a novel method that provides exact three-dimensional (3D) information on both microscopic morphology and gene expression, over a virtually unlimited spatial range, by reconstruction from serial immunostained tissue slices. Quantitative 3D assessment of tumour budding at the cancer-host interface in human pancreatic, colorectal, lung and breast adenocarcinoma suggests collective cell migration as the mechanism of cancer cell invasion, while single cancer cell migration seems to be virtually absent. Budding tumour cells display a shift towards spindle-like as well as a rounded morphology. This is associated with decreased E-cadherin staining intensity and a shift from membranous to cytoplasmic staining, as well as increased nuclear ZEB1 expression.
Published: 2014
Full Text: View/download PDF

16. Large granulation cells on the surface of the giant star π

Author: C, Paladini, F, Baron, A, Jorissen, J-B, Le Bouquin, B, Freytag, S, Van Eck, M, Wittkowski, J, Hron, A, Chiavassa, J-P, Berger, C, Siopis, A, Mayer, G, Sadowski, K, Kravchenko, S, Shetye, F, Kerschbaum, J, Kluska, and S, Ramstedt
Abstract: Convection plays a major part in many astrophysical processes, including energy transport, pulsation, dynamos and winds on evolved stars, in dust clouds and on brown dwarfs. Most of our knowledge about stellar convection has come from studying the Sun: about two million convective cells with typical sizes of around 2,000 kilometres across are present on the surface of the Sun-a phenomenon known as granulation. But on the surfaces of giant and supergiant stars there should be only a few large (several tens of thousands of times larger than those on the Sun) convective cells, owing to low surface gravity. Deriving the characteristic properties of convection (such as granule size and contrast) for the most evolved giant and supergiant stars is challenging because their photospheres are obscured by dust, which partially masks the convective patterns. These properties can be inferred from geometric model fitting, but this indirect method does not provide information about the physical origin of the convective cells. Here we report interferometric images of the surface of the evolved giant star π
Published: 2017

17. L’histoire extravagante de l’appendice et de l’appendicectomie : de la Renaissance à la vidéochirurgie

Author: J.-L. Berrod, P. Bonnichon, and J.-P. Berger
Subjects: Surgery
Abstract: Resume Les diagnostics apparemment simples ne sont pas toujours les plus faciles. Ainsi, nous avons retrace l’incroyable parcours qui fut necessaire pour admettre le concept d’appendicite et les modalites de son traitement chirurgical. Apres une longue periode preparatoire qui recouvre les xvi e et xvii e siecles, Francois Melier fut le premier, en 1837, qui relia la lesion anatomique, le diagnostic clinique et le traitement chirurgical. Durant le xix e siecle, le diagnostic et la pratique chirurgicale se developperent d’abord aux Etats-Unis, puis en France apres l’episode fâcheux de Leon Gambetta. Marquee initialement d’une morbidite lourde (20 %), le pronostic vital fut transforme par l’association de l’antibiotherapie apparue au cours de la seconde guerre mondiale et la morbidite fut alors abaissee a 2 %. Enfin, depuis une vingtaine d’annees, la videochirurgie a permis un traitement chirurgical mini-invasif. Ira-t-on plus loin dans cette evolution therapeutique en traitant medicalement ? Cependant, l’appendicite reste encore une maladie grave et imprevisible chez les enfants et chez les patients immunodeprimes. Il est permis de poser la question au debut du xxi e siecle ou l’on decrit a nouveau la typhlite, cette fois-ci plus credible…
Published: 2013
Full Text: View/download PDF

18. The close circumstellar environment of Betelgeuse

Author: Guy Perrin, Andrea Chiavassa, Michel Aurière, Sylvestre Lacour, Pierre Kervella, P. Mathias, J. P. Berger, Xavier Haubois, M. Montargès, A. López-Ariste, S. T. Ridgway, J.-B. Le Bouquin, Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), 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), Laboratoire Franco-Chilien d'Astronomie (LFCA), Universidad de Concepción [Chile]-Pontificia Universidad Católica de Chile (UC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Universidad de Chile, Joseph Louis LAGRANGE (LAGRANGE), 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), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), 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)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées, National Optical Astronomical Observatory (NOAO), European Southern Observatory (ESO), PHASE, the high-angular resolution partnership between ONERA, Observatoire de Paris, CNRS, and University Denis Diderot Paris 7, Programme National de Physique Stellaire (PNPS) of CNRS/INSU, France, NASA - Contrat : HST-GO-12610.001-A, 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), 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 national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), 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), 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), National Optical Astronomy Observatory (NOAO), Universidad de Chile = University of Chile [Santiago] (UCHILE)-Pontificia Universidad Católica de Chile (UC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Universidad de Concepción - University of Concepcion [Chile], 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 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 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, Centre National de la Recherche Scientifique (CNRS)-Universidad de Concepción [Chile]-Pontificia Universidad Católica de Chile (UC)-Universidad de Chile-Institut national des sciences de l'Univers (INSU - CNRS), 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: Convection, FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, individual: Betelgeuse, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Red supergiant, 010303 astronomy & astrophysics, infrared: stars, Solar and Stellar Astrophysics (astro-ph.SR), Convection cell, Betelgeuse, Physics, Photosphere, 010308 nuclear & particles physics, Astronomy and Astrophysics, supergiants, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], stars: imaging, Interstellar medium, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, techniques: interferometric, Astrophysics::Earth and Planetary Astrophysics, stars: mass-loss
Abstract: Context. The mass-loss mechanism of cool massive evolved stars is poorly understood. The proximity of Betelgeuse makes it an appealing target to study its atmosphere, map the shape of its envelope, and follow the structure of its wind from the photosphere out to the interstellar medium. Aims. A link is suspected between the powerful convective motions in Betelgeuse and its mass loss. We aim to constrain the spatial structure and temporal evolution of the convective pattern on the photosphere and to search for evidence of this link. Methods. We report new interferometric observations in the infrared H band using the VLTI/PIONIER instrument. We monitored the photosphere of Betelgeuse between 2012 January and 2014 November to look for evolutions that may trigger the outflow. Results. Our interferometric observations at low spatial frequencies are compatible with the presence of a hot spot on the photosphere that has a characteristic width of one stellar radius. It appears to be superposed on the smaller scale convective pattern. In the higher spatial frequency domain, we observe a significant difference between the observations and the predictions of 3D hydrodynamical simulations. Conclusions. We bring new evidence for the presence of a convective pattern in the photosphere of red supergiants. The inferred hot spot is probably the top of a giant convection cell although an asymmetric extension of the star cannot be excluded by these interferometric observations alone. The properties of the observed surface features show a stronger contrast and inhomogeneity as predicted by 3D radiative hydrodynamical simulations. We propose that the large observed feature is modifying the signature of the convective pattern at the surface of the star in a way that simulations cannot reproduce., Comment: 11 pages, 4 figures, 2016, A&A, 588, A130
Published: 2016
Full Text: View/download PDF

19. THE PULSATION OF χ CYGNI IMAGED BY OPTICAL INTERFEROMETRY: A NOVEL TECHNIQUE TO DERIVE DISTANCE AND MASS OF MIRA STARS

Author: Sylvestre Lacour, S. T. Ridgway, P. A. Schuller, Ettore Pedretti, John D. Monnier, H. Le Coroller, Rafael Millan-Gabet, M. G. Lacasse, J. P. Berger, Xavier Haubois, A. Poncelet, Henry C. Woodruff, W. A. Traub, Guy Perrin, Serge Meimon, Éric Thiébaut, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Angular acceleration, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astrophysics, 01 natural sciences, Acceleration, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Solar mass, Astronomy and Astrophysics, Radius, Delta-v (physics), Radial velocity, Amplitude, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Limb darkening, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: We present infrared interferometric imaging of the S-type Mira star Chi Cygni. The object was observed at four different epochs in 2005-2006 with the IOTA optical interferometer (H band). Images show up to 40% variation in the stellar diameter, as well as significant changes in the limb darkening and stellar inhomogeneities. Model fitting gave precise time-dependent values of the stellar diameter, and reveals presence and displacement of a warm molecular layer. The star radius, corrected for limb darkening, has a mean value of 12.1 mas and shows a 5.1mas amplitude pulsation. Minimum diameter was observed at phase 0.94+/-0.01. Maximum temperature was observed several days later at phase 1.02+/-0.02. We also show that combining the angular acceleration of the molecular layer with CO (Delta v = 3) radial velocity measurements yields a 5.9+/-1.5 mas parallax. The constant acceleration of the CO molecules -- during 80% of the pulsation cycle -- lead us to argument for a free-falling layer. The acceleration is compatible with a gravitational field produced by a 2.1(+1.5/-0.7) solar mass star. This last value is in agreement with fundamental mode pulsator models. We foresee increased development of techniques consisting in combining radial velocity with interferometric angular measurements, ultimately allowing total mapping of the speed, density, and position of the diverse species in pulsation driven atmospheres., Comment: 36 pages, accepted in ApJ
Published: 2009
Full Text: View/download PDF

20. Detection of non-radial pulsation and faint companion in the symbiotic star CH Cyg

Author: William C. Danchi, Peter G. Tuthill, Nathalie Thureau, Marc G. Lacasse, J.-P. Berger, John D. Monnier, Wesley A. Traub, Rafael Millan-Gabet, P. A. Schuller, Nathaniel P. Carleton, Ettore Pedretti, F. P. Schloerb, Sylvestre Lacour, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Brightness, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Star (graph theory), 01 natural sciences, Asymmetry, 010309 optics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, media_common, Physics, Astronomy and Astrophysics, Giant star, Radial velocity, Orbit, Wavelength, Astrophysics - Solar and Stellar Astrophysics, [SDU]Sciences of the Universe [physics], Space and Planetary Science, Symbiotic star, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: We have detected asymmetry in the symbiotic star CH Cyg through the measurement of precision closure-phase with the IONIC beam combiner, at the IOTA interferometer. The position of the asymmetry changes with time and is correlated with the phase of the 2.1-yr period found in the radial velocity measurements for this star. We can model the time-dependent asymmetry either as the orbit of a low-mass companion around the M giant or as an asymmetric, 20% change in brightness across the M giant. We do not detect a change in the size of the star during a 3 year monitoring period neither with respect to time nor with respect to wavelength. We find a spherical dust-shell with an emission size of 2.2+/-0.1 D* FWHM around the M giant star. The star to dust flux ratio is estimated to be 11.63+/-0.3. While the most likely explanation for the 20% change in brightness is non-radial pulsation we argue that a low-mass companion in close orbit could be the physical cause of the pulsation. The combined effect of pulsation and low-mass companion could explain the behaviour revealed by the radial-velocity curves and the time-dependent asymmetry detected in the closure-phase data. If CH Cyg is a typical long secondary period variable then these variations could be explained by the effect of an orbiting low-mass companion on the primary star., Comment: 11 pages 5 figures, accepted MNRAS
Published: 2009
Full Text: View/download PDF

21. First Images of R Aquarii and Its Asymmetric H2O Shell

Author: M. G. Lacasse, W. C. Danchi, Lee Anne Willson, John D. Monnier, H. Le Coroller, S. Ragland, W. D. Cotton, E. Pluzhnik, J. P. Berger, W. A. Traub, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Mira variable, R Aquarii, 010308 nuclear & particles physics, Point source, Astrophysics (astro-ph), Continuum (design consultancy), Shell (structure), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, law.invention, Wavelength, Space and Planetary Science, law, 0103 physical sciences, Closure phase, Astrophysics::Solar and Stellar Astrophysics, Maser, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: We report imaging observations of the symbotic long-period Mira variable R Aquarii (R Aqr) at near-infrared and radio wavelengths. The near-infrared observations were made with the IOTA imaging interferometer in three narrow-band filters centered at 1.51, 1.64, and 1.78 $\mu$m, which sample mainly water, continuum, and water features, respectively. Our near-infrared fringe visibility and closure phase data are analyzed using three models. (a) A uniform disk model with wavelength-dependent sizes fails to fit the visibility data, and is inconsistent with the closure phase data. (b) A three- component model, comprising a Mira star, water shell, and an off-axis point source, provide a good fit to all data. (c) A model generated by a constrained image reconstruction analysis provides more insight, suggesting that the water shell is highly non-uniform, i.e., clumpy. The VLBA observations of SiO masers in the outer molecular envelope show evidence of turbulence, with jet-like features containing velocity gradients., Comment: Accepted for publication in ApJ
Published: 2008
Full Text: View/download PDF

22. The limb-darkened Arcturus: imaging with the IOTA/IONIC interferometer

Author: S. Lacour, S. Meimon, E. Thiébaut, G. Perrin, T. Verhoelst, E. Pedretti, P. A. Schuller, L. Mugnier, J. Monnier, J. P. Berger, X. Haubois, A. Poncelet, G. Le Besnerais, K. Eriksson, R. Millan-Gabet, S. Ragland, M. Lacasse, W. Traub, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Brightness, optical interferometer, fundamental parameters [stars], k-giants, FOS: Physical sciences, double star, Atmospheric model, Astrophysics, angular diameters, 01 natural sciences, law.invention, 010309 optics, Telescope, effective temperature, law, 0103 physical sciences, Arcturus, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, iota, Physics, beam-combination, Photosphere, near-infrared interferometry, stars [infrared], individual : arcturus [stars], Astrophysics (astro-ph), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Effective temperature, interferometric [techniques], Interferometry, individual: Arcturus [stars], Space and Planetary Science, Limb darkening, stellar atmosphere models, Astrophysics::Earth and Planetary Astrophysics, radial-velocity variations
Abstract: This paper is an H band interferometric examination of Arcturus, a star frequently used as a spatial and spectral calibrator. Using the IOTA 3 telescope interferometer, we performed spectro-interferometric observation (R~35) of Arcturus. Atmospheric models and prescriptions were fitted to the data to derive the brightness distribution of the photosphere. Image reconstruction was also obtained using two software algorithms: Wisard and Mira. An achromatic power law proved to be a good model of the brightness distribution, with a limb darkening compatible with the one derived from atmospheric model simulations using our Marcs model. A Rosseland diameter of 21.05+/-0.21 was derived, corresponding to an effective temperature of T_eff=4295+/-26 K. No companion was detected from the closure phases, with an upper limit on the brightness ratio of 8e-4 at 1AU. Dynamic range at such distance from the photosphere was established at 1.5e-4 (1sigma rms). An upper limit of 1.7e-3 was also derived for the level of brightness asymmetries present on the photosphere., 12 pages, 12 figures, accepted in A&A
Published: 2008
Full Text: View/download PDF

23. Physical Orbit for λ Virginis and a Test of Stellar Evolution Models

Author: A. Claret, Guillermo Torres, Ettore Pedretti, P. Kern, Rafael Millan-Gabet, F. P. Schloerb, Wesley A. Traub, John D. Monnier, N. P. Carleton, Fabien Malbet, K. Perraut, Ming Zhao, J. P. Berger, M. G. Lacasse, A. F. Boden, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, 010308 nuclear & particles physics, Metallicity, Astrophysics (astro-ph), FOS: Physical sciences, Binary number, Astronomy and Astrophysics, Scale (descriptive set theory), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Lambda, 01 natural sciences, Stars, Orbit, 13. Climate action, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Infrared Optical Telescope Array, 010303 astronomy & astrophysics, Stellar evolution, Astrophysics::Galaxy Astrophysics
Abstract: Lambda Virginis (LamVir) is a well-known double-lined spectroscopic Am binary with the interesting property that both stars are very similar in abundance but one is sharp-lined and the other is broad-lined. We present combined interferometric and spectroscopic studies of LamVir. The small scale of the LamVir orbit (~20 mas) is well resolved by the Infrared Optical Telescope Array (IOTA), allowing us to determine its elements as well as the physical properties of the components to high accuracy. The masses of the two stars are determined to be 1.897 Msun and 1.721 Msun, with 0.7% and 1.5% errors respectively, and the two stars are found to have the same temperature of 8280 +/- 200 K. The accurately determined properties of LamVir allow comparisons between observations and current stellar evolution models, and reasonable matches are found. The best-fit stellar model gives LamVir a subsolar metallicity of Z=0.0097, and an age of 935 Myr. The orbital and physical parameters of LamVir also allow us to study its tidal evolution time scales and status. Although currently atomic diffusion is considered to be the most plausible cause of the Am phenomenon, the issue is still being actively debated in the literature. With the present study of the properties and evolutionary status of LamVir, this system is an ideal candidate for further detailed abundance analyses that might shed more light on the source of the chemical anomalies in these A stars., Comment: 43 Pages, 13 figures. Accepted for publication in ApJ
Published: 2007
Full Text: View/download PDF

24. Disk and wind interaction in the young stellar object MWC 297 spatially resolved with AMBER/VLTI

Author: F. Malbet, M. Benisty, W.-J. de Wit, S. Kraus, A. Meilland, F. Millour, E. Tatulli, J.-P. Berger, O. Chesneau, K.-H. Hofmann, A. Isella, A. Natta, R. G. Petrov, T. Preibisch, P. Stee, L. Testi, G. Weigelt, P. Antonelli, U. Beckmann, Y. Bresson, A. Chelli, M. Dugué, G. Duvert, S. Gennari, L. Glück, P. Kern, S. Lagarde, E. Le Coarer, F. Lisi, K. Perraut, P. Puget, F. Rantakyrö, S. Robbe-Dubois, A. Roussel, G. Zins, M. Accardo, B. Acke, K. Agabi, E. Altariba, B. Arezki, E. Aristidi, C. Baffa, J. Behrend, T. Blöcker, S. Bonhomme, S. Busoni, F. Cassaing, J.-M. Clausse, J. Colin, C. Connot, A. Delboulbé, A. Domiciano de Souza, T. Driebe, P. Feautrier, D. Ferruzzi, T. Forveille, E. Fossat, R. Foy, D. Fraix-Burnet, A. Gallardo, E. Giani, C. Gil, A. Glentzlin, M. Heiden, M. Heininger, O. Hernandez Utrera, D. Kamm, M. Kiekebusch, D. Le Contel, J.-M. Le Contel, T. Lesourd, B. Lopez, M. Lopez, Y. Magnard, A. Marconi, G. Mars, G. Martinot-Lagarde, P. Mathias, P. Mège, J.-L. Monin, D. Mouillet, D. Mourard, E. Nussbaum, K. Ohnaka, J. Pacheco, C. Perrier, Y. Rabbia, S. Rebattu, F. Reynaud, A. Richichi, A. Robini, M. Sacchettini, D. Schertl, M. Schöller, W. Solscheid, A. Spang, P. Stefanini, M. Tallon, I. Tallon-Bosc, D. Tasso, F. Vakili, O. von der Lühe, J.-C. Valtier, M. Vannier, and N. Ventura
Subjects: Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Young stellar object, Continuum (design consultancy), Visibility (geometry), Equator, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Spectral line, Wavelength, Space and Planetary Science, 0103 physical sciences, Thick disk, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Line (formation)
Abstract: The young stellar object MWC 297 has been observed with the VLT interferometer equipped with the AMBER instrument. MWC 297 has been spatially resolved in the continuum with a visibility of 0.50 as well as in the Br gamma emission line where the visibility decrease to a lower value of 0.33. This change in the visibility with the wavelength can be interpreted by the presence of an optically thick disk responsible for the visibility in the continuum and of a stellar wind traced by Br gamma and whose apparent size is 40% larger. We validate this interpretation by building a model of the stellar environment that combines a geometrically thin, optically thick accretion disk model consisting of gas and dust, and a latitude-dependent stellar wind outflowing above the disk surface. The continuum emission and visibilities obtained from this model are fully consistent with the interferometric AMBER data. They agree also with existing optical, near-infrared spectra and other broad-band near-infrared interferometric visibilities. A picture emerges in which MWC 297 is surrounded by an equatorial flat disk that is possibly still accreting and an outflowing wind which has a much higher velocity in the polar region than at the equator. [abridged]
Published: 2007
Full Text: View/download PDF

25. Cerebrospinal Fluid (CSF) Lactate and Pyruvate in Acute Neurological Situations

Author: J. P. Berger and R. Fawer
Subjects: Pathology, medicine.medical_specialty, Cerebrospinal fluid, business.industry, Medicine, business, Csf lactate
Published: 2015
Full Text: View/download PDF

26. First Surface‐resolved Results with the Infrared Optical Telescope Array Imaging Interferometer: Detection of Asymmetries in Asymptotic Giant Branch Stars

Author: David Malin, Rafael Millan-Gabet, F. P. Schloerb, Wesley A. Traub, P. Kern, Michael R. Pearlman, W. D. Cotton, John D. Monnier, P. Labeye, Ettore Pedretti, J. P. Berger, Charles H. Townes, Fabien Malbet, K. Perraut, S. Ragland, Gary Wallace, Kamal Souccar, W. C. Danchi, Nathaniel P. Carleton, P. Haguenauer, M. G. Lacasse, M. Brewer, Lee Anne Willson, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Brightness, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Asymmetry, Stars, Wavelength, Interferometry, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Asymptotic giant branch, Angular resolution, Astrophysics::Earth and Planetary Astrophysics, Infrared Optical Telescope Array, 010303 astronomy & astrophysics, Caltech Library Services, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, media_common
Abstract: International audience; We have measured nonzero closure phases for about 29% of our sample of 56 nearby asymptotic giant branch (AGB) stars, using the three-telescope Infrared Optical Telescope Array (IOTA) interferometer at near-infrared wavelengths (H band) and with angular resolutions in the range 5-10 mas. These nonzero closure phases can only be generated by asymmetric brightness distributions of the target stars or their surroundings. We discuss how these results were obtained and how they might be interpreted in terms of structures on or near the target stars. We also report measured angular sizes and hypothesize that most Mira stars would show detectable asymmetry if observed with adequate angular resolution.
Published: 2006
Full Text: View/download PDF

27. Keck Interferometer Observations of FU Orionis Objects

Author: Gautam Vasisht, Chas Beichman, M. Shao, R. Billmeier, Robert R. Thompson, Peter G. Tuthill, John D. Monnier, M. Hrynevych, D. Le Mignant, Bertrand Mennesson, M. Mark Colavita, Rafael Millan-Gabet, Marc J. Kuchner, G. van Belle, J.-P. Berger, Lynne A. Hillenbrand, Paola D'Alessio, Nuria Calvet, J. Gathright, S. Melnikov, Anneila I. Sargent, Stephen C. Unwin, A. Booth, A. Tannirkulam, Chris Neyman, Mark R. Swain, Peter Wizinowich, C. Koresko, Rachel Akeson, Michelle Creech-Eakman, Lee Hartmann, Wesley A. Traub, R. Ligon, A. F. Boden, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, 010504 meteorology & atmospheric sciences, Infrared, Scattering, Astrophysics::High Energy Astrophysical Phenomena, Young stellar object, Astrophysics (astro-ph), FOS: Physical sciences, Spectral density, Astronomy and Astrophysics, Field of view, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Interferometry, Amplitude, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Visibility, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences
Abstract: We present new K-band long baseline interferometer observations of three young stellar objects of the FU Orionis class, V1057 Cyg, V1515 Cyg and Z CMa-SE, obtained at the Keck Interferometer during its commissioning science period. The interferometer clearly resolves the source of near-infrared emission in all three objects. Using simple geometrical models we derive size scales (0.5-4.5 AU) for this emission. All three objects appear significantly more resolved than expected from simple models of accretion disks tuned to fit the broadband optical and infrared spectro-photometry. We explore variations in the key parameters that are able to lower the predicted visibility amplitudes to the measured levels, and conclude that accretion disks alone do not reproduce the spectral energy distributions and K-band visibilities simultaneously. We conclude that either disk models are inadequate to describe the near-infrared emission, or additional source components are needed. We hypothesize that large scale emission (10s of AU) in the interferometer field of view is responsible for the surprisingly low visibilities. This emission may arise in scattering by large envelopes believed to surround these objects., Accepted by The Astrophysical Journal, in press
Published: 2006
Full Text: View/download PDF

28. Role of PPARs in the regulation of obesity-related insulin sensitivity and inflammation

Author: D E Moller and J P Berger
Subjects: medicine.medical_specialty, Endocrinology, Diabetes and Metabolism, medicine.medical_treatment, Anti-Inflammatory Agents, Receptors, Cytoplasmic and Nuclear, Medicine (miscellaneous), Alpha (ethology), Peroxisome proliferator-activated receptor, Ligands, Proinflammatory cytokine, Insulin resistance, Internal medicine, medicine, Animals, Humans, Obesity, Inflammation, chemistry.chemical_classification, Nutrition and Dietetics, biology, Insulin, Lipid metabolism, medicine.disease, Insulin receptor, Endocrinology, chemistry, biology.protein, lipids (amino acids, peptides, and proteins), Peroxisome proliferator-activated receptor delta, Insulin Resistance, Transcription Factors
Abstract: Peroxisome proliferator-activated receptors (PPARs) are nuclear receptor isoforms with key roles in the regulation of lipid and glucose metabolism. Synthetic ligands for PPAR gamma (and PPAR alpha) have effects of promoting insulin sensitization in the context of obesity. Recent evidence suggests that activation of PPAR delta might produce similar effects. Both PPAR gamma and PPAR alpha have also been shown to produce selected anti-inflammatory effects and to reduce the progression of atherosclerosis in animals (alpha and gamma) or in humans (alpha). Mechanisms underlying insulin-sensitizing effects are complex. For PPAR gamma, direct effects on adipose tissue lipid metabolism with secondary benefits in liver and/or muscle (lipid levels and insulin signaling) have been implicated. For PPAR alpha, accelerated lipid catabolism may contribute to reduced muscle or liver 'steatosis'. Anti-inflammatory mechanisms as contributors to the beneficial metabolic effects of PPAR activation are also worth considering for the following reasons: (1) obesity and insulin resistance are associated with a proinflammatory milieu. (2) PPAR gamma has clear effects to oppose the effects of tumor necrosis factor-alpha (TNFalpha) in adipocytes. (3) effects of PPAR ligands on cytokine-mediated signaling (eg via NF-kappa B) may be expected to enhance insulin action. (4) Adipose production of several molecules that are implicated as markers or mediators of inflammation is reduced. (5) In humans, treatment with either PPAR alpha or PPAR gamma agonists has been shown to reduce circulating levels of proteins that serve as markers of inflammation. (6) Adiponectin, a fat-derived circulating factor that has been implicated as having anti-inflammatory activity, is induced by PPAR gamma agonism.
Published: 2003
Full Text: View/download PDF

29. Sub–Astronomical Unit Structure of the Near-Infrared Emission from AB Aurigae

Author: Rafael Millan-Gabet, Fabien Malbet, F. P. Schloerb, J. D. Bregman, J.-P. Berger, and Wesley A. Traub
Subjects: Physics, Be star, Astrophysics::High Energy Astrophysical Phenomena, Spatially resolved, Near-infrared spectroscopy, Astronomical unit, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Radius, Interferometry, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Infrared Optical Telescope Array, Astrophysics::Galaxy Astrophysics
Abstract: We present near-infrared, long-baseline, interferometric observations of AB Aurigae, a well-known Herbig Ae/Be star, obtained with the Infrared Optical Telescope Array. The near-infrared emission from this source has been spatially resolved for the first time, and the observations indicate a characteristic diameter of 5 mas for the emission, corresponding to 0.7 AU at the distance of AB Aur. The data appear to be most consistent with models in which the circumstellar material around AB Aurigae lies in a flattened structure with a central large hole or optically thin region of radius about 0.3 AU.
Published: 1999
Full Text: View/download PDF

30. European pressurized water reactor: safety objectives and principles

Author: K.-E. Schmidt, J. Czech, M. Serret, M. Yvon, J. Wirkner, J.-P. Berger, U. Krugmann, and M. Grenet
Subjects: Nuclear and High Energy Physics, Computer science, Mechanical Engineering, Pressurized water reactor, Environmental engineering, law.invention, Unit (housing), Nuclear Energy and Engineering, Containment, law, Risk analysis (business), Order (exchange), Nuclear power plant, Safety engineering, Systems engineering, media_common.cataloged_instance, General Materials Science, European union, Safety, Risk, Reliability and Quality, Waste Management and Disposal, media_common
Abstract: The approach for the EPR is largely evolutionary in order to make best use of existing experiences in designing and operating PWRs in France and Germany. Furthermore, this enables large unit sizes and contributes to economics. However, innovative features have been considered necessary in order to improve design compared to existing designs in some areas and to achieve a low level of risk, both for core melt and for large releases.
Published: 1999
Full Text: View/download PDF

31. Ultrasonography as an aid to diagnosis and treatment in a rural African hospital: a prospective study of 1,119 cases

Author: J P Berger and J P Steinmetz
Subjects: Adult, Male, Pediatrics, medicine.medical_specialty, Adolescent, MEDLINE, Context (language use), Rural Health, Diagnostic aid, Surveys and Questionnaires, Tropical Medicine, Virology, Humans, Medicine, Cameroon, Prospective Studies, Child, Prospective cohort study, Developing Countries, Aged, Retrospective Studies, Ultrasonography, business.industry, Rural health, Infant, Newborn, Infant, Retrospective cohort study, Middle Aged, Infectious Diseases, Child, Preschool, Female, Parasitology, business
Abstract: The aim of this study was to assess the utility of ultrasonography in a rural African hospital in Cameroon with scarce resources. A prospective questionnaire was administered and completed for each of the 1,119 consecutive cases included in the study. Among these 1,119 cases, the diagnosis made by clinicians and by echography could be verified by another means for 323 patients. Ultrasonography showed abnormal findings in 78% of the cases. In the group of 323 patients in which the diagnosis made by echography could be verified, it was correct in 95.4% of the cases, erroneous in 4.6% of the cases, judged useful for diagnosis in 67.8% of the cases, and not contributive in 27.6% of the cases. Ultrasonography was judged useful when treatment was decided upon in 62% of the cases. This study demonstrated the value of ultrasonography in the context of a developing country and the conditions by which its use could be delineated.
Published: 1999
Full Text: View/download PDF

32. FU Orionis Resolved by Infrared Long-Baseline Interferometry at a 2 AU Scale

Author: F. Malbet, J.-P. Berger, M. M. Colavita, C. D. Koresko, C. Beichman, A. F. Boden, S. R. Kulkarni, B. F. Lane, D. W. Mobley, X. P. Pan, M. Shao, G. T. Van Belle, and J. K. Wallace
Subjects: Physics, Photosphere, Infrared, Scattering, Young stellar object, Astrophysics (astro-ph), Resolution (electron density), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Lambda, Interferometry, Palomar Testbed Interferometer, Space and Planetary Science
Abstract: We present the first infrared interferometric observations of a young stellar object with a spatial projected resolution better than 2 AU. The observations were obtained with the Palomar Testbed Interferometer. FU Ori exhibits a visibility of V^2 =0.72 +/- 0.07 for a 103 +/- 5 m projected baseline at lambda = 2.2 microns. The data are consistent on the spatial scale probed by PTI both with a binary system scenario (maximum magnitude difference of 2.7 +/- 0.5 mag and smallest separation of 0.35 +/- 0.05 AU) and a standard luminous accretion disk model (approx. accretion rate of 6e-5 Mo/yr) where the thermal emission dominates the stellar scattering, and inconsistent with a single stellar photosphere., 13 pages, 4 figures, accepted for publication in ApJL
Published: 1998
Full Text: View/download PDF

33. Zooming in: high resolution 3D reconstruction of differently stained histological whole slide images

Author: J. P. Berger, Bernd Lahrmann, Janine Olesch, Oliver Sedlaczek, Hendrik Laue, Niels Grabe, Kai Breuhahn, André Homeyer, Johannes Lotz, Arne Warth, Stefan Heldmann, Michael Schwier, and Benedikt Müller
Subjects: Visual inspection, Computer science, business.industry, 3D reconstruction, Image registration, High resolution, Histology, Computer vision, Artificial intelligence, Zoom, business, 3D modeling
Abstract: Much insight into metabolic interactions, tissue growth, and tissue organization can be gained by analyzing differently stained histological serial sections. One opportunity unavailable to classic histology is three-dimensional (3D) examination and computer aided analysis of tissue samples. In this case, registration is needed to reestablish spatial correspondence between adjacent slides that is lost during the sectioning process. Furthermore, the sectioning introduces various distortions like cuts, folding, tearing, and local deformations to the tissue, which need to be corrected in order to exploit the additional information arising from the analysis of neighboring slide images. In this paper we present a novel image registration based method for reconstructing a 3D tissue block implementing a zooming strategy around a user-defined point of interest. We efficiently align consecutive slides at increasingly fine resolution up to cell level. We use a two-step approach, where after a macroscopic, coarse alignment of the slides as preprocessing, a nonlinear, elastic registration is performed to correct local, non-uniform deformations. Being driven by the optimization of the normalized gradient field (NGF) distance measure, our method is suitable for differently stained and thus multi-modal slides. We applied our method to ultra thin serial sections (2 μm) of a human lung tumor. In total 170 slides, stained alternately with four different stains, have been registered. Thorough visual inspection of virtual cuts through the reconstructed block perpendicular to the cutting plane shows accurate alignment of vessels and other tissue structures. This observation is confirmed by a quantitative analysis. Using nonlinear image registration, our method is able to correct locally varying deformations in tissue structures and exceeds the limitations of globally linear transformations.
Published: 2014
Full Text: View/download PDF

34. 2D and 3D MALDI-imaging: Conceptual strategies for visualization and data mining

Author: J. P. Berger, Wolfgang Dreher, Bernd M. Fischer, Jan Hendrik Kobarg, Jan Strehlow, Stefan Wirtz, Peter Maass, Stefan Heldmann, Herbert Thiele, Dennis Trede, Janina Oetjen, and Publica
Subjects: MALDI imaging, Scanner, Computer science, business.industry, Biophysics, Analytical chemistry, Image registration, Biochemistry, Analytical Chemistry, Visualization, Imaging, Three-Dimensional, Data visualization, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Data analysis, Data Mining, Computer vision, Segmentation, Artificial intelligence, business, Cluster analysis, Molecular Biology, Chromatography, Liquid
Abstract: 3D imaging has a significant impact on many challenges in life sciences, because biology is a 3-dimensional phenomenon. Current 3D imaging-technologies (various types MRI, PET, SPECT) are labeled, i.e. they trace the localization of a specific compound in the body. In contrast, 3D MALDI mass spectrometry-imaging (MALDI-MSI) is a label-free method imaging the spatial distribution of molecular compounds. It complements 3D imaging labeled methods, immunohistochemistry, and genetics-based methods. However, 3D MALDI-MSI cannot tap its full potential due to the lack of statistical methods for analysis and interpretation of large and complex 3D datasets. To overcome this, we established a complete and robust 3D MALDI-MSI pipeline combined with efficient computational data analysis methods for 3D edge preserving image denoising, 3D spatial segmentation as well as finding colocalized m/z values, which will be reviewed here in detail. Furthermore, we explain, why the integration and correlation of the MALDI imaging data with other imaging modalities allows to enhance the interpretation of the molecular data and provides visualization of molecular patterns that may otherwise not be apparent. Therefore, a 3D data acquisition workflow is described generating a set of 3 different dimensional images representing the same anatomies. First, an in-vitro MRI measurement is performed which results in a three-dimensional image modality representing the 3D structure of the measured object. After sectioning the 3D object into N consecutive slices, all N slices are scanned using an optical digital scanner, enabling for performing the MS measurements. Scanning the individual sections results into low-resolution images, which define the base coordinate system for the whole pipeline. The scanned images conclude the information from the spatial (MRI) and the mass spectrometric (MALDI-MSI) dimension and are used for the spatial three-dimensional reconstruction of the object performed by image registration techniques. Different strategies for automatic serial image registration applied to MS datasets are outlined in detail. The third image modality is histology driven, i.e. a digital scan of the histological stained slices in high-resolution. After fusion of reconstructed scan images and MRI the slice-related coordinates of the mass spectra can be propagated into 3D-space. After image registration of scan images and histological stained images, the anatomical information from histology is fused with the mass spectra from MALDI-MSI. As a result of the described pipeline we have a set of 3 dimensional images representing the same anatomies, i.e. the reconstructed slice scans, the spectral images as well as corresponding clustering results, and the acquired MRI. Great emphasis is put on the fact that the co-registered MRI providing anatomical details improves the interpretation of 3D MALDI images. The ability to relate mass spectrometry derived molecular information with in vivo and in vitro imaging has potentially important implications. This article is part of a Special Issue entitled: Computational Proteomics in the Post-Identification Era. Guest Editors: Martin Eisenacher and Christian Stephan.
Published: 2014

35. MRI-compatible pipeline for three-dimensional MALDI imaging mass spectrometry using PAXgene fixation

Author: Stefan Wirtz, Axel Walch, Herbert Thiele, Michael Gottschalk, Michaela Aichler, Peter Maass, Michael Becker, Stefan Heldmann, Dennis Trede, Theodore Alexandrov, Stefan Schiffler, Janina Oetjen, Jan Hendrik Kobarg, J. P. Berger, Jan Strehlow, and Publica
Subjects: Proteomics, MALDI imaging, Proteome, Biophysics, Analytical chemistry, Biology, Kidney, 01 natural sciences, Biochemistry, Mice, 03 medical and health sciences, Microscopy, medicine, Animals, Segmentation, Databases, Protein, 030304 developmental biology, Fixation (histology), 0303 health sciences, medicine.diagnostic_test, 010401 analytical chemistry, Volume rendering, Magnetic resonance imaging, Magnetic Resonance Imaging, 0104 chemical sciences, Visualization, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Biomedical engineering
Abstract: MALDI imaging mass spectrometry (MALDI-imaging) has emerged as a spatially-resolved label-free bioanalytical technique for direct analysis of biological samples and was recently introduced for analysis of 3D tissue specimens. We present a new experimental and computational pipeline for molecular analysis of tissue specimens which integrates 3D MALDI-imaging, magnetic resonance imaging (MRI), and histological staining and microscopy, and evaluate the pipeline by applying it to analysis of a mouse kidney. To ensure sample integrity and reproducible sectioning, we utilized the PAXgene fixation and paraffin embedding and proved its compatibility with MRI. Altogether, 122 serial sections of the kidney were analyzed using MALDI-imaging, resulting in a 3D dataset of 200 GB comprised of 2 million spectra. We show that elastic image registration better compensates for local distortions of tissue sections. The computational analysis of 3D MALDI-imaging data was performed using our spatial segmentation pipeline which determines regions of distinct molecular composition and finds m/z-values co-localized with these regions. For facilitated interpretation of 3D distribution of ions, we evaluated isosurfaces providing simplified visualization. We present the data in a multimodal fashion combining 3D MALDI-imaging with the MRI volume rendering and with light microscopic images of histologically stained sections. Biological significance Our novel experimental and computational pipeline for 3D MALDI-imaging can be applied to address clinical questions such as proteomic analysis of the tumor morphologic heterogeneity. Examining the protein distribution as well as the drug distribution throughout an entire tumor using our pipeline will facilitate understanding of the molecular mechanisms of carcinogenesis. This article is part of a Special Issue entitled: From Genome to Proteome: Open Innovations.
Published: 2013

36. Accompanying optical interferometry worldwide: the JMMC tools and services

Author: H. Beust, Florentin Millour, D. Bonneau, Karine Perraut, S. Lafrasse, Fabien Malbet, Olivier Chesneau, Michel Tallon, Xavier Delfosse, Alain Chelli, Jean-Louis Monin, Jacques Kluska, Antoine Mérand, Martin Vannier, Myriam Benisty, Pierre Cruzalèbes, J.-B. Le Bouquin, Gilles Duvert, Pierre Kervella, I. Tallon-Bosc, Guillaume Mella, L. Bourgès, Denis Mourard, Laurent M. Mugnier, Olivier Absil, A. Domiciano de Souza, J. P. Berger, Serge Meimon, and Nicolas Nardetto
Subjects: Interferometry, Software, Software suite, business.industry, Computer science, Listing (computer), Virtual observatory, business, Data science, Simulation
Abstract: This poster advertizes the Jean-Marie Mariotti Center software tools, databases and services aimed at facilitating the use of optical interferometry worldwide such as preparation of observations, data reduction and data analysis. Its mission and organization are presented before listing the current software suite. Finally some facts and perspectives are mentioned.
Published: 2012
Full Text: View/download PDF

37. Two telescopes ABCD electro-optic beam combiner based on lithium niobate for near infrared stellar interferometry

Author: Alain Delboulbé, M. Gineys, Samuel Heidmann, J. P. Berger, T. Moulin, J.-B. Le Bouquin, Guillermo Martin, Laurent Jocou, A. Nolot, and O. Caballero
Subjects: Wavefront, Physics, business.industry, Lithium niobate, Optical communication, Phase (waves), Single-mode optical fiber, Physics::Optics, law.invention, Interferometry, chemistry.chemical_compound, Optics, chemistry, Achromatic lens, law, Optoelectronics, business, Group delay and phase delay
Abstract: Lithium Niobate (LN) based electro-optic modulators are well known in the optical communications field, due to their high bandwidth and deep rejection ratio [1]. These performances could be used in the field of astronomy for stellar interferometry in the mid-infrared domain [2]. With our partners from Photline Technologies, we have conceived, developed and characterized a 2T ABCD [3] beam combiner in the near-infrared (1.5μm, the H-band in astrophysics). The modulation scheme, presented below in Figure 1, allows to determine the fringe characteristics in a single shot measurement, without the need to externally scan the optical phase delay. Fine adjustment of the relative phase can be achieved using the electro-optic properties of the lithium niobate waveguides. In particular, the phase on each output can be electrically controlled and locked by using appropriate electrodes. These devices have to ensure modal filtering to reject optical aberrations of the wavefront and thus optimize the fringes contrast, which means that they have to be single mode through all the spectral range of interest. This also means that the couplers should be achromatic and balanced in order to optimize the fringe contrast. We will present results on global transmission, performance of the couplers and the electro-optic behavior of the device using monochromatic as well as wide spectral sources in the H-band.
Published: 2011
Full Text: View/download PDF

38. GRAVITY: a four-telescope beam combiner instrument for the VLTI

Author: Laurent Jocou, Markus Schöller, R.-R. Rohloff, Sylvestre Lacour, Xavier Haubois, Philippe B. Gitton, Andreas Eckart, Guy Perrin, Christian Straubmeier, Th. Henning, Constanza Araujo-Hauck, H. Bartko, Frank Eisenhauer, Stefan Hippler, Pedro Carvas, O. Pfuhl, D. Moch, A. Gräter, Pierre Kervella, Nadia Kudryavtseva, Sebastian Rabien, M. Haug, Rainer Lenzen, Y. Clénet, Kevin Wagner, S. Kellner, M. Wiest, Damian Moratschke, Senol Yazici, P. Fédou, Arnaud Sevin, Stefan Gillessen, J. M. Rees, C. Collin, Gérard Rousset, F. Chapron, Juan-Luis Ramos, M. Thiel, António Amorim, D. Ziegler, Frédéric Gonté, Reiner Hofmann, A. Nolot, K. Perraut, Reinhard Genzel, Elodie Choquet, Ralf Klein, Vianak Naranjo, Eric Gendron, Pierre Léna, Pierre Haguenauer, Udo Neumann, Thibaut Moulin, T. Paumard, Harald Baumeister, J. P. Berger, Wolfgang Brandner, Sebastian Fischer, D. Rouan, Werner Laun, J. Lima, Vincent Lapeyrere, Frédéric Cassaing, 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), Pôle Astronomie du LESIA, 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)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Ingénieurs, Techniciens et Administratifs
Subjects: Physics, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy, Field of view, Astrometry, Metrology, law.invention, Black hole, Telescope, Interferometry, law, Magnitude (astronomy), Astrophysics::Solar and Stellar Astrophysics, Adaptive optics, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics
Abstract: GRAVITY is an adaptive optics assisted Beam Combiner for the second generation VLTI instrumentation. The instrument will provide high-precision narrow-angle astrometry and phase-referenced interferometric imaging in the astronomical K-band for faint objects. We describe the wide range of science that will be tackled with this instrument, highlighting the unique capabilities of the VLTI in combination with GRAVITY. The most prominent goal is to observe highly relativistic motions of matter close to the event horizon of Sgr A*, the massive black hole at center of the Milky Way. We present the preliminary design that fulfils the requirements that follow from the key science drivers: It includes an integrated optics, 4-telescope, dual feed beam combiner operated in a cryogenic vessel; near-infrared wavefrontsensing adaptive optics; fringe-tracking on secondary sources within the field of view of the VLTI and a novel metrology concept. Simulations show that 10 {\mu}as astrometry within few minutes is feasible for a source with a magnitude of mK = 15 like Sgr A*, given the availability of suitable phase reference sources (mK = 10). Using the same setup, imaging of mK = 18 stellar sources in the interferometric field of view is possible, assuming a full night of observations and the corresponding UV coverage of the VLTI., Comment: 20 pages, Proceedings SPIE Astronomical Telescopes and Instrumentation Conference 2010
Published: 2010
Full Text: View/download PDF

39. Strong near-infrared emission in the sub-AU disk of the Herbig Ae star HD163296: evidence for refractory dust?

Author: A. Mérand, A. Natta, Gilles Duvert, Leonardo Testi, Fabien Malbet, Johan Olofsson, J-B. LeBouquin, Stefan Kraus, Martin Vannier, J.-P. Berger, A. Isella, F. Massi, S. Robbe-Dubois, Myriam Benisty, Gerd Weigelt, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Division of Geological and Planetary Sciences [Pasadena], California Institute of Technology (CALTECH), European Southern Observatory, European Southern Observatory (ESO), Max-Planck-Institut für Radioastronomie (MPIFR), Laboratoire Hippolyte Fizeau (FIZEAU), Université Nice Sophia Antipolis (... - 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, 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), and Faure, Alexandre
Subjects: Physics, 010308 nuclear & particles physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Near-infrared spectroscopy, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Star (graph theory), [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 01 natural sciences, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, K band, Phase (matter), 0103 physical sciences, Closure phase, Spectral energy distribution, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Spectral resolution, 010303 astronomy & astrophysics, Refractory (planetary science), ComputingMilieux_MISCELLANEOUS, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics
Abstract: We present new long-baseline spectro-interferometric observations of the HerbigAe star HD163296 obtained in the H and K bands with the AMBER instrument at VLTI. The observations cover a range of spatial resolutions between 3 and 12 milli-arcseconds, with a spectral resolution of ~30. With a total of 1481 visibilities and 432 closure phases, they result in the best (u,v) coverage achieved on a young star so far. The circumstellar material is resolved at the sub-AU spatial scale and closure phase measurements indicate a small but significant deviation from point-symmetry. We discuss the results assuming that the near-infrared excess in HD163296 is dominated by the emission of a circumstellar disk. A successful fit to the spectral energy distribution, near-infrared visibilities and closure phases is found with a model where a dominant contribution to the H and K band emissions arises from an optically thin, smooth and point-symmetric region extending from about 0.1 to 0.45 AU. At the latter distance from the star, silicates condense, the disk becomes optically thick and develops a puffed-up rim, whose skewed emission can account for the non-zero closure phases. We discuss the nature of the inner disk emission and tentatively rule out dense molecular gas as well as optically thin atomic or ionized gas as its possible origin. We propose instead that the inner emission traces the presence of very refractory grains in a partially cleared region, extending at least to 0.5 AU. If so, we may be observing the disk of HD163296 just before it reaches the transition disk phase. However, we note that the nature of the refractory grains or even the possibility for any grain to survive at the very high temperatures we require (~2100-2300 K at 0.1 AU from the star) is unclear and should be investigated further., 14 pages; 12 figures; accepted by A&A
Published: 2010
Full Text: View/download PDF

40. An integrated optics beam combiner for the second generation VLTI instruments

Author: M. Benisty, J.-P. Berger, L. Jocou, P. Labeye, F. Malbet, K. Perraut, P. Kern, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Computer science, Aperture synthesis, FOS: Physical sciences, 01 natural sciences, law.invention, 010309 optics, Optics, Optical path, law, K band, 0103 physical sciences, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Very Large Telescope, business.industry, Near-infrared spectroscopy, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, H band, Polarization (waves), Wavelength, Interferometry, Space and Planetary Science, Achromatic lens, business, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The very recent years have seen a promising start in scientific publications making use of images produced by near-infrared long-baseline interferometry. The technique has reached, at last, a technical maturity level that opens new avenues for numerous astrophysical topics requiring milli-arcsecond model-independent imaging. The Very Large Telescope Interferometer (VLTI) is on the path to be equipped with instruments capable to combine between four to six telescopes. In the framework of the VLTI second generation instruments Gravity and VSI, we propose a new beam combining concept using Integrated Optics (IO) technologies with a novel ABCD-like fringe encoding scheme. Our goal is to demonstrate that IO-based combination brings considerable advantages in terms of instrumental design and performance. We therefore aim at giving a full characterization of an IO beam combiner to establish its performances and check its compliance with the specifications of an imaging instrument. Laboratory measurements were made in the H band with a dedicated testbed. We studied the beam combiners through the analysis of throughput, instrumental visibilities, phases and closure phases in wide band as well as with spectral dispersion. Study of the polarization properties is also done. We obtain competitive throughput, high and stable instrumental contrasts, stable but non-zero closure phases which we attribute to internal well calibrable optical path differences. We validate a new static and achromatic phase shifting IO function close to the nominal 90deg value. All these observables show limited chromaticity over the H band range. Our results demonstrate that such ABCD-like beam combiners are particularly well suited to achieve aperture synthesis imaging. This opens the way to extend to all near infrared wavelengths and in particular, the K band., 13 pages, 11 figures, 13 tables; Accepted by A&A
Published: 2009
Full Text: View/download PDF

41. Imaging the asymmetric dust shell around CI Cam with long baseline optical interferometry

Author: Michael R. Garcia, Wesley A. Traub, John D. Monnier, Ettore Pedretti, A. Tannirkulam, Nathalie Thureau, J.-P. Berger, F. P. Schloerb, Rafael Millan-Gabet, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Palomar Testbed Interferometer, 0103 physical sciences, interferometric -circumstellar matter -stars, Astrophysics::Solar and Stellar Astrophysics, Angular resolution, Infrared Optical Telescope Array, individual, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, 010308 nuclear & particles physics, high angular resolution -techniques, Astronomy and Astrophysics, Spectral bands, Position angle, 3. Good health, Wavelength, Interferometry, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Closure phase, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, techniques, CI Cam
Abstract: We present the first high angular resolution observation of the B[e] star/X-ray transient object CI Cam, performed with the two-telescope Infrared Optical Telescope Array (IOTA), its upgraded three-telescope version (IOTA3T) and the Palomar Testbed Interferometer (PTI). Visibilities and closure phases were obtained using the IONIC-3 integrated optics beam combiner. CI Cam was observed in the near-infrared H and K spectral bands, wavelengths well suited to measure the size and study the geometry of the hot dust surrounding CI Cam. The analysis of the visibility data over an 8 year period from soon after the 1998 outburst to 2006 shows that the dust visibility has not changed over the years. The visibility data shows that CI Cam is elongated which confirms the disc-shape of the circumstellar environment and totally rules out the hypothesis of a spherical dust shell. Closure phase measurements show direct evidence of asymmetries in the circumstellar environment of CI Cam and we conclude that the dust surrounding CI Cam lies in an inhomogeneous disc seen at an angle. The near-infrared dust emission appears as an elliptical skewed Gaussian ring with a major axis a = 7.58 +/- 0.24 mas, an axis ratio r = 0.39 +/- 0.03 and a position angle theta = 35 +/- 2 deg., Comment: 9 pages, 5 figures, accepted MNRAS
Published: 2009
Full Text: View/download PDF

42. GRAVITY: Astrometry on the galactic center and beyond

Author: Xavier Haubois, Vianak Naranjo, J. Ziegleder, P. Fédou, António Amorim, Jose Ramos, S. Lacour, Fabien Malbet, Nico Hamaus, L. Jocou, Stefan Hippler, Eric Gendron, A. Böhm, Werner Laun, M. Thiel, Oliver Pfuhl, Stefan Gillessen, Sebastian Rabien, Guy Perrin, Daniel Rouan, Harald Baumeister, Katie Dodds-Eden, K. Houairi, Christian Straubmeier, Th. Henning, Markus Schöller, Rainer Lenzen, Jorge Lima, A. Gräter, J. Kolmeder, Udo Neumann, Reinhard Genzel, Gérard Rousset, Thibaut Paumard, Pierre Kervella, J.-P. Berger, Andrea Richichi, Reiner Hofmann, Frédéric Cassaing, R.-R. Rohloff, Andreas Eckart, Marcus Haug, Ralf Klein, Felix Hormuth, K. Perraut, H. Bartko, Frank Eisenhauer, Wolfgang Brandner, Yann Clénet, S. Kellner, 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), Pôle Astronomie du LESIA, 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)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Ingénieurs, Techniciens et Administratifs, Groupement d'Intérêt Scientifique du Partenariat Haute résolution Angulaire Sol-Espace (GIS PHASE ), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Max-Planck-Institut für Astronomie (MPIA), Physikalisches Institut, Universität zu Köln, European Southern Observatory (ESO), Max-Planck-Institut für Extraterrestriche Physik (MPE), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ONERA, and SIM/IDL, Faculdade de Ciências da Universidade de Lisboa
Subjects: Wavefront, Physics, Event horizon, Milky Way, Galactic Center, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Field of view, Astrometry, Black hole, Space and Planetary Science, Adaptive optics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics::Galaxy Astrophysics
Abstract: International audience; We present the second-generation VLTI instrument GRAVITY, which currently is in the preliminary design phase. GRAVITY is specifically designed to observe highly relativistic motions of matter close to the event horizon of Sgr A*, the massive black hole at the center of the Milky Way. We have identified the key design features needed to achieve this goal and present the resulting instrument concept. It includes an integrated optics, four-telescope, dual feed beam combiner operated in a cryogenic vessel, near-infrared wavefront sensing adaptive optics, fringe tracking on secondary sources within the field of view of the VLTI and a novel metrology concept. Simulations show that the planned design matches the scientific needs; in particular that 10 muas astrometry is feasible for a source with a magnitude of mK = 15 like Sgr A*, given the availability of suitable phase reference sources.
Published: 2009
Full Text: View/download PDF

43. Milli-arcsecond Astrophysics with VSI, the VLTI Spectro-imager in the ELT Era

Author: F. Malbet, D. Buscher, G. Weigelt, P. Garcia, M. Gai, D. Lorenzetti, J. Surdej, J. Hron, R. Neuhäuser, P. Kern, L. Jocou, J.-P. Berger, O. Absil, U. Beckmann, L. Corcione, G. Duvert, M. Filho, P. Labeye, E. Le Coarer, G. Li Causi, J. Lima, K. Perraut, E. Tatulli, E. Thiébaut, J. Young, G. Zins, A. Amorim, B. Aringer, T. Beckert, M. Benisty, X. Bonfils, A. Chelli, O. Chesneau, A. Chiavassa, R. Corradi, M. de Becker, A. Delboulbé, G. Duchêne, T. Forveille, C. Haniff, E. Herwats, K.-H. Hofmann, J.-B. Le Bouquin, S. Ligori, D. Loreggia, A. Marconi, A. Moitinho, B. Nisini, P.-O. Petrucci, J. Rebordao, R. Speziali, L. Testi, F. Vitali, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Cavendish Laboratory, University of Cambridge [UK] (CAM), Max-Planck-Institut für Radioastronomie (MPIFR), Laboratoire de Modélisation Multi-échelles des Combustibles (LM2C), Service d'Etudes de Simulation du Comportement du combustibles (SESC), Département d'Etudes des Combustibles (DEC), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), INAF - Osservatorio Astrofisico di Torino (OATo), Istituto Nazionale di Astrofisica (INAF), Osservatorio di Astrofisica di Roma (OAR), Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Institut für Astrophysik [Wien], Universität Wien, Astrophysical Institute and University Observatory [Jena] (AIU), Friedrich-Schiller-Universität Jena, Institut d'Electronique du Solide et des Systèmes (InESS), Centre National de la Recherche Scientifique (CNRS), Centre d'Études Préhistoire, Antiquité, Moyen-Age (CEPAM), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto [Porto], Laboratoire d'Electronique et des Technologies de l'Information (CEA-LETI), Université Grenoble Alpes (UGA)-Direction de Recherche Technologique (CEA) (DRT (CEA)), INAF - Osservatorio Astronomico di Roma (OAR), SIM/IDL Faculdade de Ciências da Universidade de Lisboa (FCUL), University of Lisboa, Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS 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), Institut für Astronomie, Universität Wien (IFA), Laboratoire Gemini (LG), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Groupe de Recherche en Astronomie et Astrophysique du Languedoc (GRAAL), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto de Astrofisica de Canarias (IAC), Département Recherches Subatomiques (DRS-IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), Instituto Nacional de Engenharia, Tecnologia e Inovacco (INETI), European Southern Observatory (ESO), Department of Computer Science and Engineering [Bologna] (DISI), Università di Bologna [Bologna] (UNIBO), A. Moorwood, VSI collaboration, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Friedrich-Schiller-Universität = Friedrich Schiller University Jena [Jena, Germany], 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), Universidade do Porto, 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)), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), Instituto Nacional de Engenharia, Tecnologia e Inovacao (INETI), Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Université Nice Sophia Antipolis (1965 - 2019) (UNS), Universidade do Porto = University of Porto, École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-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)
Subjects: Physics, Active galactic nucleus, Mode (statistics), Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Domain (software engineering), [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Stars, Interferometry, Wavelength, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: 8 pages. To be published in the proceedings of the ESO workshop "Science with the VLT in the ELT Era", held in Garching (Germany) on 8-12 October 2007, A. Moorwood editor.; Nowadays, compact sources relatively warm like surfaces of nearby stars, circumstellar environments of stars from early stages to the most evolved ones and surroundings of active galactic nuclei can be investigated at milli-arcsecond scales only with the VLT in its interferometric mode. We propose a spectro-imager, named VSI (VLTI spectro-imager), which is capable to probe these sources both over spatial and spectral scales in the near-infrared domain. This instrument will provide information complementary to what is obtained at the same time with ALMA at different wavelengths and the extreme large telescopes.
Published: 2009
Full Text: View/download PDF

44. PEGASE, an infrared interferometer to study stellar environments and low mass companions around nearby stars

Author: M. Ollivier, O. Absil, F. Allard, J.-P. Berger, P. Bordé, F. Cassaing, B. Chazelas, A. Chelli, O. Chesneau, V. Coudé du Foresto, D. Defrère, P. Duchon, P. Gabor, J. Gay, E. Herwats, S. Jacquinod, P. Kern, P. Kervella, J.-M. Le Duigou, A. Léger, B. Lopez, F. Malbet, D. Mourard, D. Pelat, G. Perrin, Y. Rabbia, D. Rouan, J.-M. Reiss, G. Rousset, F. Selsis, P. Stee, J. Surdej, 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), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Étude des Phénomènes de Transfert et de l'Instantanéité : Agro-industrie et Bâtiment (LEPTIAB), Université de La Rochelle (ULR), 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), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Laboratoire Hippolyte Fizeau (FIZEAU), Université Nice Sophia Antipolis (... - 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), Laboratoire Bordelais de Recherche en Informatique (LaBRI), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB), Laboratoire Gemini (LG), 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)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'étude des Mécanismes de la recombinaison (LMR), Centre National de la Recherche Scientifique (CNRS), Departement d'Astrophysique Extragalactique et de Cosmologie (DAEC), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), 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), Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, 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), La Rochelle Université (ULR), Université Nice Sophia Antipolis (1965 - 2019) (UNS), Université de Bordeaux (UB)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Centre National de la Recherche Scientifique (CNRS), 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), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Cosmic Vision, Infrared, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 7. Clean energy, 010309 optics, 0103 physical sciences, 010303 astronomy & astrophysics, Low mass objects, Astrophysics::Galaxy Astrophysics, Physics, Spacecraft, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Interferometry, Stars, Space interferometry, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Darwin (spacecraft), Astrophysics::Earth and Planetary Astrophysics, Nulling interferometry, business, Low Mass, Circumstellar habitable zone
Abstract: International audience; PEGASE is a mission dedicated to the exploration of the environment (including habitable zone) of young and solar-type stars (particularly those in the DARWIN catalogue) and the observation of low mass companions around nearby stars. It is a space interferometer project composed of three free flying spacecraft, respectively featuring two 40 cm siderostats and a beam combiner working in the visible and near infrared. It has been proposed to ESA as an answer to the first “Cosmic Vision” call for proposals, as an M mission. The concept also enables full-scale demonstration of space nulling interferometry operation for DARWIN.
Published: 2009
Full Text: View/download PDF

45. Prospects for near-infrared characterisation of hot Jupiters with the VLTI Spectro-Imager (VSI)

Author: Olivier Absil, X. Bonfils, J. P. Berger, Fabien Malbet, S. Renard, and T. Forveille
Subjects: Physics, Stars, Planet, Hot Jupiter, Astrophysics::Instrumentation and Methods for Astrophysics, Closure phase, Astrophysics::Earth and Planetary Astrophysics, Emission spectrum, Astrophysics, Spectral resolution, Exoplanet, Spectral line
Abstract: In this paper, we study the feasibility of obtaining near-infrared spectra of bright extrasolar planets with the 2nd generation VLTI Spectro-Imager instrument (VSI), which has the required angular resolution to resolve nearby hot Extrasolar Giant Planets (EGPs) from their host stars. Taking into account fundamental noises, we simulate closure phase measurements of several extrasolar systems using four 8-m telescopes at the VLT and a low spectral resolution (R = 100). Synthetic planetary spectra from T. Barman are used as an input. Standard chi2-fitting methods are then used to reconstruct planetary spectra from the simulated data. These simulations show that low-resolution spectra in the H and K bands can be retrieved with a good fidelity for half a dozen targets in a reasonable observing time (about 10 hours, spread over a few nights). Such observations would strongly constrain the planetary temperature and albedo, the energy redistribution mechanisms, as well as the chemical composition of their atmospheres. Systematic errors, not included in our simulations, could be a serious limitation to these performance estimations. The use of integrated optics is however expected to provide the required instrumental stability (around 10^-4 on the closure phase) to enable the first thorough characterisation of extrasolar planetary emission spectra in the near-infrared.
Published: 2008
Full Text: View/download PDF

46. Right arm involvement and pain extension can help to differentiate coronary diseases from chest pain of other origin: a prospective emergency ward study of 278 consecutive patients admitted for chest pain

Author: G. van Melle, Bertrand Yersin, E. Haller, Thierry Buclin, and J. P. Berger
Subjects: Male, Thorax, Chest Pain, medicine.medical_specialty, Myocardial Infarction, Pain, Coronary Disease, Heart Auscultation, Disease, Chest pain, Constriction, Diagnosis, Differential, Internal medicine, Internal Medicine, medicine, Humans, Prospective Studies, Myocardial infarction, Prospective cohort study, Unstable angina, business.industry, Middle Aged, medicine.disease, Arm, Cardiology, Female, medicine.symptom, Emergency Service, Hospital, business
Abstract: In a prospective study of 278 consecutive patients admitted to an emergency ward for chest pain, the 115 clinical and paraclinical parameters available at the time of admission were evaluated by computer comparison with the final diagnoses. The most valuable items for making the diagnosis were classified according to their sensitivity, specificity and predictive value. Among the 278 patients, 100 individuals had myocardial infarctions (MI), 47 had unstable angina, 25 had stable angina and 106 patients had a non-coronary disease. The twelve most sensitive items for distinguishing MI from other conditions were the following: sudden onset of pain (70%): duration of more than 60 min (88%): constriction and squeezing (79%): oppression (75%): prior anginal attacks (61%): sex male (72%): age over 60 years (74%): abnormal heart auscultation (62%): abnormal electrocardiogram (ECG)(98%): segment (ST) disturbances (86%): increased glucose level (77%): CKMB fraction greater than 6% of total creatine kinase (CK) level (63%). Among the twelve most specific items, also with the best positive predictive value, irradiation in the right arm is of most importance: among the 51 patients with right arm involvement, 48 suffered from a coronary disease and 41 from a myocardial infarction. The largest extension of pain was reported in the latter group. It is concluded that chest pain with a wide irradiation involving the right arm strongly suggests that a myocardial infarction is ongoing.
Published: 1990
Full Text: View/download PDF

47. Multiway Beam Combiners for VITRUV

Author: L. Jocou, Myriam Benisty, P. Labeye, and J.-P. Berger
Subjects: Materials science, Photometric calibration, Optics, business.industry, business, Silicon etching, Beam (structure)
Published: 2007
Full Text: View/download PDF

48. Measurement of the Total Hadronic Cross-Section Below the Upsilon(4S) Resonance at BaBar Using Initial-State Radiation

Author: Nicolas J. P. Berger
Subjects: Physics, Nuclear physics, Range (particle radiation), Cross section (physics), Particle physics, Electron–positron annihilation, Hadron, Resonance, Production (computer science), State (functional analysis), Radiation
Abstract: The authors present an inclusive measurement of {Delta}{alpha}{sub had}{sup (5)}(m{sub Z}{sup 2}) at BABAR using the Initial State Radiation (ISR) technique in e{sup +}e{sup -} interactions to simultaneously explore the whole low energy range at reduced center-of-mass energies below 7 GeV, where the current knowledge of e{sup +}e{sup -} {yields} hadrons production limits the precision of the prediction of the running of {alpha}. The BABAR ISR data sample is considerably larger than existing e{sup +}e{sup -} R scan measurement data over most of the low energy range, and there are also many systematic advantages with the ISR technique to allow significantly improved precision on the integral for {Delta}{alpha}{sub had}{sup (5)}(m{sub Z}{sup 2}). This thesis reports on a measurement of {Delta}{alpha}{sub had}{sup (5)}(m{sub Z}{sup 2}) at the 3% precision level, improving on the current knowledge of this quantity.
Published: 2007
Full Text: View/download PDF

49. Visual/infrared interferometry of Orion Trapezium stars: Preliminary dynamical orbit and aperture synthesis imaging of the Theta 1 Orionis C system

Author: Karl-Heinz Hofmann, Ettore Pedretti, John D. Monnier, K. Ohnaka, Dieter Schertl, Wesley A. Traub, Gerd Weigelt, Rafael Millan-Gabet, Stefan Kraus, Y. Y. Balega, F. P. Schloerb, Th. Preibisch, J. P. Berger, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Aperture synthesis, media_common.quotation_subject, FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, Telescope, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Eccentricity (behavior), 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common, O-type star, Physics, 010308 nuclear & particles physics, Astrophysics (astro-ph), Astronomy and Astrophysics, Observable, Orbit, Stars, Space and Planetary Science, Orbital motion, Astrophysics::Earth and Planetary Astrophysics
Abstract: Located in the Orion Trapezium cluster, Theta 1 Orionis C is one of the youngest and nearest high-mass stars (O5-O7) and also known to be a close binary system. Using new multi-epoch visual and near-infrared bispectrum speckle interferometric observations obtained at the BTA 6 m telescope, and IOTA near-infrared long-baseline interferometry, we trace the orbital motion of the Theta 1 Ori C components over the interval 1997.8 to 2005.9, covering a significant arc of the orbit. Besides fitting the relative position and the flux ratio, we apply aperture synthesis techniques to our IOTA data to reconstruct a model-independent image of the Theta 1 Ori C binary system. The orbital solutions suggest a high eccentricity (e approx. 0.91) and short-period (P approx. 10.9 yrs) orbit. As the current astrometric data only allows rather weak constraints on the total dynamical mass, we present the two best-fit orbits. From these orbital solutions one can be favoured, implying a system mass of 48 M_sun and a distance to the Trapezium cluster of 434 pc. When also taking the measured flux ratio and the derived location in the HR-diagram into account, we find good agreement for all observables, assuming a spectral type of O5.5 for Theta 1 Ori C1 (M=34.0 M_sun) and O9.5 for C2 (M=15.5 M_sun). We find indications that the companion C2 is massive itself, which makes it likely that its contribution to the intense UV radiation field of the Trapezium cluster is non-negligible. Furthermore, the high eccentricity of the preliminary orbit solution predicts a very small physical separation during periastron passage (approx. 1.5 AU, next passage around 2007.5), suggesting strong wind-wind interaction between the two O stars., Comment: 13 pages, 9 figures, Accepted for publication in Astronomy & Astrophysics
Published: 2007
Full Text: View/download PDF

50. VITRUV Precursors: IONIC2T/IONIC3T

Author: Fabien Malbet, P. Haguenauer, I. Schanen, Myriam Benisty, Markus Schöller, Laurent Jocou, J. B. Lebouquin, John D. Monnier, P. Labeye, Ettore Pedretti, Wesley A. Traub, K. Perraut, Rafael Millan-Gabet, J. P. Berger, Andreas Glindemann, Alain Delboulbé, and P. Kern
Subjects: Physics, Young stellar object, Closure phase, Astrophysics
Published: 2007
Full Text: View/download PDF

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Language

Publication Type

Journal

Database

Publisher

121 results on '"J. P. Berger"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources