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Universität zu Köln
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Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut

Radiative transfer in turbulent clouds

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Line radiative transfer

Closely related to the study of molecular cloud structure is the inverstigation and theoretical modelling of line radiative transfer in turbulent clouds needed to translate between the three-dimensional physical cloud structure and the observable line profiles.

We compute full 3-D line radiative transfer effects using a two scale-approximation (Ossenkopf 2002) applicable to any turbulent density and velocity field. Line tracers are sensitive to narrow gas density intervals only, but the information from their profiles is essential to constrain the turbulent velocity structure.


Comparison of the CO 2-1 map of MCLD123.5+24.9 in the Polaris Flare taken with the KOSMA 3m telescope (left) and the corresponding map from a simple fractal cloud model (right). The fractal model is able to reproduce the statistical properties of the observation and shows thus a similar kind of structure.

The line radiative transfer in three dimensional turbulent structures is simulated and the resulting maps are compared to the observations. This extends the analysis to the third dimension providing a clue to the real cloud structure. From comparisons with MHD models we can learn about the nature of turbulence in molecular clouds.