Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2010-01-14
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
A&A, accepted
Scientific paper
We aim to better understand how the spatial structure of molecular clouds is governed by turbulence. For that, we study the large-scale spatial distribution of low density molecular gas and search for characteristic length scales. We employ a 35 square degrees 13CO 1-0 molecular line survey of Cygnus X and visual extinction (A_V) maps of 17 Galactic clouds to analyse the spatial structure using the Delta-variance method. This sample contains a large variety of different molecular cloud types with different star forming activity. The Delta-variance spectra obtained from the A_V maps show differences between low-mass star-forming (SF) clouds and massive giant molecular clouds (GMC) in terms of shape of the spectrum and its power-law exponent beta. Low-mass SF clouds have a double-peak structure with characteristic size scales around 1 pc (though with a large scatter around this value) and 4 pc. GMCs show no characteristic scale in the A_V-maps, which can partly be ascribed to a distance effect due to a larger line-of-sight (LOS) confusion. The Delta-variance for Cygnus, determined from the 13CO survey, shows characteristic scales at 4 pc and 40 pc, either reflecting the filament structure and large-scale turbulence forcing or - for the 4 pc scale - the scale below which the 13CO 1-0 line becomes optically thick. Though there are different processes that can introduce characteristic scales, i.e. geometry, decaying turbulence the transition scale from supersonic to subsonic turbulence (the sonic scale), line-of-sight effects and energy injection due to expanding supernova shells, outflows, HII-regions, and the relative contribution of these effects strongly varies from cloud to cloud, it is remarkable that the resulting turbulent structure of molecular clouds shows similar characteristics.
Andre Pascal
Bontemps Sylvain
Brunt Christopher
Federrath Christoph
Klessen Ralf
No associations
LandOfFree
The link between molecular cloud structure and turbulence does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The link between molecular cloud structure and turbulence, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The link between molecular cloud structure and turbulence will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-568265