EPoS Contribution
EPoS Contribution
Quantifying Filamentary Collapse Modes in Molecular Clouds

Volker Ossenkopf-Okada
KOSMA, Koeln, DE
We propose a novel technique to measure the spectrum of filaments in any two-dimensional data set. Using anisotropic wavelets we can quantify and distinguish local and global anisotropies and measure the size distribution of filaments. The unbiased view to the Herschel column density maps of the Polaris Flare and the Aquila molecular cloud does not confirm any universal characteristic filament width. The maps show an almost scale-free filamentary spectrum up to the size of the dominating filament. This has a width of about 0.3 pc in Polaris and 0.15 pc in Aquila. The filaments in Polaris show no preferential direction in contrast to the global alignment that we trace in Aquila.
By comparing the power in isotropic and anisotropic structures we can measure the relative importance of spherical and cylindrical collapse modes and their spatial distribution. All substructures in Polaris are gravitationally stable. In Aquila we find regions prone to cylindrical collapse and others prone to spherical collapse. The fastest collapse is expected for a cyclindrical mode in the main filament.
Caption: Spatial distribution and size of the collapse modes in Aquila obtained from the column density map (left). The central figure shows the spherical collapse modes, the right one the cyclindrical modes. The colors quantify the length of the gravitational interaction being proportional to the local free-fall time.
R. Stepanov, ICMM, RU
N. Schneider, KOSMA, DE
Suggested Session: Filaments