Properties of interstellar filaments as derived from Herschel observations

We present a scenario for filament formation and evolution motivated by recent observational results of nearby molecular clouds. The analysis of more than 250 filaments observed in 7 regions by the Herschel Gould Belt Survey show that the filaments are characterized by a narrow distribution of central width sharply peaked at ∼ 0.1 pc. This typical filament width corresponds, within a factor of ∼ 2 to the sonic scale below which interstellar turbulence becomes subsonic in diffuse gas, which may suggest that the filaments form as a result of the dissipation of large-scale turbulence. The analysis of IRAM 30 m molecular line observations of a sample of these filaments show evidence of an increase in non-thermal velocity dispersion with column density which suggest an evolution of the supercritical filaments in mass per unit length while accreting surrounding material