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| EPoS Contribution |
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Triggered vs. turbulent fragmentation of molecular clouds
Nicola Schneider-Bontemps Sap/DAPnia-CEA, Gif-Sur-Yvette, FR | |
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Large-scale surveys in various molecular line tracers provide
constraints on the different star formation mechanisms (triggered SF
vs. turbulent fragmentation) and help to further develop and refine
turbulence models and cloud structure characterization techniques.
We thus present in this poster a study of the Cygnus X region, using wide-field imaging observations in low-J CO lines and the CS 2-1 line. An area of 35 (15) square degrees at 50" angular resolution was mapped in 13CO and C18O J=1-0 (CS 2-1 and N2H+ 1-0) at the FCRAO. The low-J transitions of CO isotopes trace gas at low densities which is distributed over all scales in molecular clouds. Applying the Delta-Variance structure analysis method will give a hint whether turbulence models driven on the largest scales reproduce the observed scaling behaviours for molecular clouds. However, Cygnus X is a high-mass star forming region where the strong dynamical influence of already formed clusters may dominate over turbulence effects. The mass distribution of dense cores and the velocity structure within the dense cores is determined using the line widths of the CS 2-1 line and the global velocity scaling behaviour is examined as well as other scaling relations (e.g. Larson relations). Since the collapse of dense cores in molecular clouds produces flattened or filamentary structures in turbulent cloud models, we will also study the geometry of the clumps seen in CS and 13CO. The ratio of major and minor axis of the clumps and the 13CO/CS mass ratio, determined by clumps finding procedures such as Gaussclumps or Clumpfind provide a statistical approach for this study. A comparison between these two programs shows the bias which is introduced by these techniques and to which extent the identification and properties of the clumps depend on the algorithm used. | |