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

We present Nobeyama 45 m telescope (CO)-O-18, (CO)-C-13, and (CO)-C-12(1-0) mapping observations towards an interstellar filament in the Taurus molecular cloud. We investigate the gas velocity structure along the filament and in its surrounding parent cloud. The filament is detected in the optically thin (CO)-O-18 emission as a single velocity component with a similar to 1 pc long, similar to 0.06 pc wide structure. The (CO)-O-18 emission traces dust column densities larger than similar to 5 x 10(21) cm(-2). The line-of-sight (LOS) velocity fluctuates along the filament crest with an average amplitude of similar to 0.2 km s(-1). The (CO)-C-13 and (CO)-C-12 integrated intensity maps show spatially extended emission around the elongated filament. We identify three extended structures with LOS velocities redshifted and blueshifted with respect to the average velocity of the filament identified in (CO)-O-18. Based on combined analyses of velocity-integrated channel maps and intensity variations of the optically thick (CO)-C-12 spectra on and off the filament, we propose a three-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 filament and 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 filament showing a velocity field compatible with the filament formation process proposed by Inoue et al. (2018, PASJ, 70, S53), where a filament is 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.