Mostrando recursos 1 - 20 de 5.476

  1. L'astronomie dans le monde - 02/2017

    Manfroid, Jean
    Matière noire - Supernova ASASSN-15lh - Tache sur Jupiter - Dioxyde de carbone - Araignées martiennes - Cassini (suite) - Cérès - Bételgeuse - Formation des galaxies - Mars humide

  2. L'astronomie dans le monde - 01/2017

    Manfroid, Jean
    Disques protoplanétaires– Rondeur naturelle – Galaxie Toile d’Araignée – Les premiers résultats d’ExoMars – Biréfringence du vide

  3. Dense Gas in Ultra-Luminous Far-Infrared Galaxies

    Baan, W. A.; Henkel, Carsten; Loenen, A. F.; Baudry, Alain; Wiklind, T.
    19 pages, 12 figures,

  4. A Study of Superbubbles in the ISM : Break-Out, Escape of LYC Photons and Molecule Formation

    Roy, Arpita
    Multiple coherent supernova explosions (SNe) in an OB association can produce a strong shock that moves through the interstellar medium (ISM). These shocks fronts carve out hot and tenuous regions in the ISM known as superbubbles. The density contour plot at three different times (0.5 Myr (left panel), 4 Myr (middle panel), 9.5 Myr (right panel)) showing different stages of superbubble evolution for n0 = 0.5 cm−3, z0 = 300 pc, and for NOB = 104. This density contour plot is produced using ZEUS-MP 2D hydrodynamic simulation with a resolution of 512 × 512 with a logarithmic grid extending...

  5. Droit de la protection sociale 6 ème édition

    Morvan, Patrick
    Cet ouvrage explore la galaxie des systèmes qui constitue le droit de la protection sociale (régimes légaux, régimes complémentaires de retraite, garanties collectives de retraite et de prévoyance dans l'entreprise, assurance chômage, aide sociale). Il démêle et décrit les règles du droit de la sécurité sociale ainsi que ses rapports avec le droit de l'Union européenne et de la CEDH (qui sont ici omniprésents), le droit processuel, le droit civil des obligations, le droit pénal, le droit du travail, le droit des affaires et le droit public. Si l'auteur accorde le premier rang au raisonnement juridique, l'étude de cette matière,...

  6. Gas inflows towards the nucleus of NGC 1358

    Schnorr Müller, Allan; Storchi-Bergmann, Thaisa; Nagar, Neil M.; Robinson, Andrew; Lena, Davide
    We use optical spectra from the inner 1.8×2.5 kpc2 of the Seyfert 2 galaxy NGC1358, obtained with the GMOS integral field spectrograph on the Gemini South telescope at a spatial resolution of ≈165 pc, to assess the feeding and feedback processes in this nearby active galaxy. Five gaseous kinematical components are observed in the emission line profiles. One of the components is present in the entire field-of-view and we interpret it as due to gas rotating in the disc of the galaxy. Three of the remaining components we interpret as associated with active galactic nucleus (AGN) feedback: a compact unresolved...

  7. Evolution of the accretion disc around the supermassive black hole of NGC 7213

    Schimoia, Jáderson da Silva; Storchi-Bergmann, Thaisa; Winge, Claudia; Nemmen, Rodrigo S.; Eracleous, Michael
    We present observations of the double-peaked broad Hα profile emitted by the active nucleus of NGC7213 using the Gemini South Telescope in 13 epochs between 2011 September 27 and 2013 July 23. This is the first time that the double-peaked line profile of this nucleus – typical of gas emission from the outer parts of an accretion disc surrounding a supermassive black hole (SMBH) – is reported to vary. From the analysis of the line profiles we find two variability time-scales: (1) the shortest one, between 7 and 28 d, is consistent with the light travel time between the ionizing...

  8. Loss of mass and stability of galaxies in modified newtonian dynamics

    Wu H. Zhao B. Famaey G. Gentile O.Tiret F. Combes G.W. Angus A.C. Robin, X.

  9. Dark-energy constraints and correlations with systematics from CFHTLS weak lensing, SNLS supernovae Ia and WMAP5

    Kilbinger, M.; Benabed, K.; Guy, J.; Astier, P.; Tereno, I.; Fu, L.; Wraith, D.; Coupon, J.; Mellier, Y.; Balland, C.; Bouchet, F. R.; Hamana, T.; Hardin, D.; McCracken, H. J.; Pain, R.; Regnault, N.; Schultheis, M.; Yahagi, H.
    Aims: We combine measurements of weak gravitational lensing from the CFHTLS-Wide survey, supernovae Ia from CFHT SNLS and CMB anisotropies from WMAP5 to obtain joint constraints on cosmological parameters, in particular, the dark-energy equation-of-state parameter w. We assess the influence of systematics in the data on the results and look for possible correlations with cosmological parameters. Methods: We implemented an MCMC algorithm to sample the parameter space of a flat CDM model with a dark-energy component of constant w. Systematics in the data are parametrised and included in the analysis. We determine the influence of photometric calibration of SNIa data...

  10. The Chemical Evolution of Galaxies by Successive starbursts

    Contini R. Coziol S. Considère E. Davoust R.E. Carlos Reyes, T.
    International audience

  11. Gentes y agentes, condiciones paradiplomáticas de la creación de una frontera móvil

    Amilhat Szary, Anne-Laure
    «¿Paradiplomacia con quién y para quién?», constituye la pregunta central de este texto, proponiendo retornar a las definiciones básicas de un campo cognitivo actualmente en proceso de consolidarse, enriqueciéndolo con los aportes de una geopolítica crítica. Se trata de reconstruir la comprensión de los procesos sociales y políticos, pero también culturales y simbólicos, que están en juego en el funcionamiento de las fronteras con-temporáneas, para ubicar con más agudeza los desafíos contenidos en las nuevas reglas del juego paradiplomático. Para tomar en cuenta la evolución del concepto de frontera, desde la definición de un límite territorial linear, contenedor de una...

  12. Accurate determination of the mass distribution in spiral galaxies

    Blais-Ouellette, S.; Amram, P.; Carignan, C.; Swaters, R.
    High resolution Fabry-Perot data of six spiral galaxies are presented. Those data extend the previous sample of spiral galaxies studied with high resolution 3D spectroscopy to earlier morphological types. All the galaxies in the sample have available H I data at 21 cm from the VLA or Westerbork. Velocity fields are analyzed and Hα rotation curves are computed and compared to H I curves. The kinematics of NGC 5055 central regions are looked at more closely. Its peculiar kinematics can be interpreted either as a bipolar outflow or as a counter-rotating disk, possibly hosting a 9 ±2 x 10^8 M_⊙...

  13. The ROSAT deep survey. VII. RX J105343+5735: A massive cluster at z = 1.263

    Thompson, D.; Pozzetti, L.; Hasinger, G.; Lehmann, I.; Schmidt, M.; Soifer, B. T.; Szokoly, G.; Wilson, G.; Zamorani, G.
    The eastern lobe of the unusual double-lobed extended X-ray source RX J105343+5735 is confirmed to be a massive cluster at high redshift. Deep optical and near-infrared imaging show an overdensity of galaxies in both X-ray lobes, including a significant excess of red galaxies (R – K > 5.3) with colors typical of elliptical galaxies at z > 1. We have used new photometry to place better constraints on the redshifts of the cluster galaxies. A Keck NIRSPEC spectrum of one of the bright central galaxies in the eastern lobe shows a narrow Hα emission line at 1.485 microns, yielding a...

  14. High-resolution SZ imaging of clusters of galaxies with the NIKA2 camera at the IRAM 30-m telescope

    Mayet, F.
    International audience

  15. The ROSAT Deep Survey. VI. X-ray sources and Optical identifications of the Ultra Deep Survey

    Lehmann, I.; Hasinger, G.; Schmidt, M.; Giacconi, R.; Trümper, J.; Zamorani, G.; Gunn, J. E.; Pozzetti, L.; Schneider, D. P.; Stanke, T.; Szokoly, G.; Thompson, D.; Wilson, G.
    The ROSAT Deep Surveys in the direction of the Lockman Hole are the most sensitive X-ray surveys performed with the ROSAT satellite. About 70-80% of the X-ray background has been resolved into discrete sources at a flux limit of ~10^(-15) erg cm^(-2) s^(-1) in the 0.5-2.0 keV energy band. A nearly complete optical identification of the ROSAT Deep Survey (RDS) has shown that the great majority of sources are AGNs. We describe in this paper the ROSAT Ultra Deep Survey (UDS), an extension of the RDS in the Lockman Hole. The Ultra Deep Survey reaches a flux level of 1.2...

  16. Warm dust and aromatic bands as quantitative probes of star-formation activity

    Förster Schreiber, N. M.; Roussel, H.; Sauvage, M.; Charmandaris, V.
    We combine samples of spiral galaxies and starburst systems observed with ISOCAM on board ISO to investigate the reliability of mid-infrared dust emission as a quantitative tracer of star formation activity. The total sample covers very diverse galactic environments and probes a much wider dynamic range in star formation rate density than previous similar studies. We find that both the monochromatic 15 μm continuum and the 5-8.5 µm emission constitute excellent indicators of the star formation rate as quantified by the Lyman continuum luminosity L_(Lye), within specified validity limits which are different for the two tracers. Normalized to projected surface...

  17. A Ku-Band Polarimeter for the Owens Valley Radio Observatory 40-Meter Telescope

    Karkare, Kirit Sukrit

    Blazars are active galactic nuclei - small, extremely luminous objects at the center of galaxies powered by material accreting around a supermassive black hole - which emit relativistic jets of highly energetic plasma along our line of sight. There is no accepted model for jet composition, acceleration, and confinement; observations at different wavelengths will help us understand these emission mechanisms. Since 2007, the 40-Meter Telescope at the Owens Valley Radio Observatory has been monitoring over 1100 blazars every two days. The variability in radio light curves is likely to be correlated with gamma-rays, which we are observing with the Fermi Gamma-Ray Space Telescope.


  18. "Super-deblended" Dust Emission in Galaxies: I. The GOODS-North Catalog and the Cosmic Star Formation Rate Density out to Redshift 6

    Liu, Daizhong; Daddi, Emanuele; Dickinson, Mark; Owen, Frazer; Pannella, Maurilio; Sargent, Mark; Béthermin, Matthieu; Magdis, Georgios; Gao, Yu; Shu, Xinwen; Wang, Tao; Jin, Shuowen; Inami, Hanae
    International audience

  19. Submillimeter C and CO Lines in Galaxies

    Gerin, M.; Phillips, T. G.; Contursi, A.
    We present measurements of the fine structure transitions of atomic carbon, and of the submillimeter rotational lines of carbon monoxide in a variety of external galaxies. We discuss the relative contributions of atomic carbon and carbon monoxide for the cooling of molecular gas in these galaxies, and how these lines can be used to determine the physical conditions in the emitting gas.

  20. The internal structure of high-Z E/S0 galaxies from LSD

    Treu, T.; Koopmans, L. V. E.
    We summarize results from the first year of the Lenses Structure and Dynamics Survey (LSD). Using the Echelle Imager and Spectrograph at the Keck-II Telescope, we have measured spatially resolved velocity dispersion profiles of a sample of distant (up to z=1) early-type galaxies that are gravitational lenses. By combining lensing and dynamical analyses we can set firm limits on the dark matter density profile, the controversial inner slope of the dark matter halo, the mass-to-light ratio of the luminous component, the total mass distribution, and on the velocity ellipsoid by breaking the mass anisotropy-relation. The implications of these measurements in...

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