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Browsing by Author "Henning, T."

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    Probing dust grain evolution in IM Lupi's circumstellar disc - Multi-wavelength observations and modelling of the dust disc
    (EDP Sciences, 2008-08-08) Pinte, C.; Padgett, D. L.; Menard, F.; Stapelfeldt, K. R.; Schneider, G.; Olofsson, J.; Panic, O.; Augereau, J. C.; Duchene, G.; Krist, J.; Pontoppidan, K.; Perrin, M. D.; Grady, C. A.; Kessler-Silacci, J.; van Dishoeck, E. F.; Lommen, D.; Silverstone, M.; Hines, D. C.; Wolf, S.; Blake, G. A.; Henning, T.; Stecklum, B.; University of Exeter; Centre National de la Recherche Scientifique (CNRS); UDICE-French Research Universities; Communaute Universite Grenoble Alpes; Universite Grenoble Alpes (UGA); California Institute of Technology; National Aeronautics & Space Administration (NASA); NASA Jet Propulsion Laboratory (JPL); University of Arizona; Leiden University; Leiden University - Excl LUMC; University of California System; University of California Berkeley; University of California Los Angeles; University of Texas System; University of Texas Austin; Max Planck Society; Eureka Scientific; University of Kiel; University of Alabama Tuscaloosa
    Aims. We present a panchromatic study, involving a multiple technique approach, of the circumstellar disc surrounding the T Tauri star IM Lupi (Sz 82). Methods. We have undertaken a comprehensive observational study of IM Lupi using photometry, spectroscopy, millimetre interferometry and multi-wavelength imaging. For the first time, the disc is resolved from optical and near-infrared wavelengths in scattered light, to the millimetre regime in thermal emission. Our data-set, in conjunction with existing photometric data, provides an extensive coverage of the spectral energy distribution, including a detailed spectrum of the silicate emission bands. We have performed a simultaneous modelling of the various observations, using the radiative transfer code MCFOST, and analysed a grid of models over a large fraction of the parameter space via Bayesian inference. Results. We have constructed a model that can reproduce all of the observations of the disc. Our analysis illustrates the importance of combining a wide range of observations in order to fully constrain the disc model, with each observation providing a strong constraint only on some aspects of the disc structure and dust content. Quantitative evidence of dust evolution in the disc is obtained: grain growth up to millimetre-sized particles, vertical stratification of dust grains with micrometric grains close to the disc surface and larger grains which have settled towards the disc midplane, and possibly the formation of fluffy aggregates and/ or ice mantles around grains.
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    STRUCTURE AND COMPOSITION OF TWO TRANSITIONAL CIRCUMSTELLAR DISKS IN CORONA AUSTRALIS
    (IOP Publishing, 2010-08-13) Hughes, A. M.; Andrews, S. M.; Wilner, D. J.; Meyer, M. R.; Carpenter, J. M.; Qi, C.; Hales, A. S.; Casassus, S.; Hogerheijde, M. R.; Mamajek, E. E.; Wolf, S.; Henning, T.; Silverstone, M. D.; Harvard University; Smithsonian Astrophysical Observatory; Smithsonian Institution; Swiss Federal Institutes of Technology Domain; ETH Zurich; California Institute of Technology; National Radio Astronomy Observatory (NRAO); Universidad de Chile; Leiden University; Leiden University - Excl LUMC; University of Rochester; University of Kiel; Max Planck Society; Eureka Scientific; University of Alabama Tuscaloosa
    The late stages of evolution of the primordial circumstellar disks surrounding young stars are poorly understood, yet vital to constraining theories of planet formation. We consider basic structural models for the disks around two similar to 10 Myr old members of the nearby RCrA association: RX J1842.9-3532 and RX J1852.3-3700. We present new arc second-resolution maps of their 230 GHz continuum emission from the Submillimeter Array and unresolved CO(3-2) spectra from the Atacama Submillimeter Telescope Experiment. By combining these data with broadband fluxes from the literature and infrared fluxes and spectra from the catalog of the Formation and Evolution of Planetary Systems Legacy program on the Spitzer Space Telescope, we assemble a multiwavelength data set probing the gas and dust disks. Using the Monte Carlo radiative transfer code RADMC to model simultaneously the spectral energy distribution and millimeter continuum visibilities, we derive basic dust disk properties and identify an inner cavity of radius 16 AU in the disk around RX J1852.3-3700. We also identify an optically thin 5 AU cavity in the disk around RX J1842.9-3532, with a small amount of optically thick material close to the star. The molecular line observations suggest an intermediate disk inclination in RX J1842.9-3532, consistent with the continuum emission. In combination with the dust models, the molecular data allow us to derive a lower CO content than expected, suggesting that the process of gas clearing is likely underway in both systems, perhaps simultaneously with planet formation.