Magnetized interstellar molecular clouds - III. Filament Collisions and Core Formation: Insights into Substructures and Evolution

Abstract

We present the results of a driven, ideal magnetohydrodynamics simulation of a molecular cloud to study the formation of filamentary structures in molecular clouds and their fragmentation into dense cloud cores. Shock compression results in the formation of sub-parsec long filamentary structures. Large-scale supersonic flows push these small filaments together and form massive filamentary clouds. The main filament that forms stretches across the full 4.4 pc length of the simulation and has a median FWHM of 0.075 pc, similar to that observed in many molecular clouds. Subfilaments inside the main filament have a median FWHM of 0.03-0.04 pc, similar to the ``fibers" observed in molecular lines. The collision and merger of subcritical subfilaments is an important mechanism for the formation of prestellar cores. Colliding subfilaments and the resulting core at their intersection is a hub-filament system similar to that associated with massive star formation, but on a smaller scale. Core mergers can be significant in the growth of pre-stellar cores and may play a role in the formation of binary stars.