EPoS Contribution
EPoS Contribution
Filament fragmentation at arbitrary length scales

Matthias Gritschneder
U Munich, Munich, DE
We analyze the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid based AMR-code RAMSES. It is well known that a straight marginable stable cylinder fragments into cores if the density is slightly perturbed. The cores form on the length scale of the fastest growing mode, set by the mass-to-line ratio of the filament. However, we discovered that a homogenous cylinder in a stable configuration starts to oscillate, is triggered into fragmentation, and collapses when it is bent, e.g. with a slight sinusoidal perturbation. This previously unstudied behaviour is important as it allows a filament to fragment at any given scale, as long as it has slight bends. In our realization in the figure below, the spacing between the cores matches the wavelength of the sinusoidal perturbation. We present a large scale parameter study investigating different wavelengths, different perturbations and various initial densities. With the help of these, we derive the oscillation period as well as the collapse timescale analytically from first principles. Furthermore, we study the behavior of a flow around the bent cylinder. The resulting surface perturbations are very reminiscent of the striation observed e.g. around B44.
Caption: KHI-instabilities around a bent cylinder in hydrostatic equilibrium. Cores have formed with a separation equal to the wavelength of the initial geometrical perturbation of the cylinder.
A. Burkert, U Munich, DE
S. Heigl, U Munich, DE
Key publication

Suggested Session: Filaments