Molecular filament formation and filament-cloud interaction: Hints from Nobeyama 45m telescope observations.

We present Nobeyama 45m telescope C18O, 13CO, and 12CO(1-0) mapping observations towards an interstellar filamentin the Taurus molecular cloud. We investigate the gas velocity structure along the filamentand in its surrounding parent cloud. The filamentis detected in the optically thin C18O emission as a single velocity component, ~1pc long, ~0.06pc wide structure. The C18O emission traces dust column densities larger than ~5x10^21 cm-2. The line-of-sight (LOS) velocity fluctuates along the filamentcrest with an average amplitude of ~0.2 km/s. The 13CO and 12CO integrated intensity mapsshow spatially extended emission around the elongated filament. We identify three extended structures with LOS velocities redshifted and blueshiftedwith respect to the average velocity of the filamentidentified in C18O. Based on combined analyses of velocity integrated channel maps and intensity variations of the optically thick 12CO spectra on and off the filament, we propose a 3-dimensional structure of the cloud surrounding the filament. We further suggest a multi-interaction scenario where sheet-like extended structures interact, in space and time, with the filamentand are responsible for its compression and/or disruption, playing an important role in the star formation history of the filament. We also identify, towards the same field, a very faint filamentshowing a velocity field compatible with the filamentformation process proposed by Inoue et al. (2017), where a filamentis formed due to convergence of a flow of matter generated by the bending of the ambient magnetic field structure induced by an interstellar shock compression.