Discovery of CCS Velocity-coherent Substructures in the Taurus Molecular Cloud 1

We present the results of mapping observations toward a nearby starless filamentary cloud, the Taurus Molecular Cloud 1 (TMC-1), in the CCS ( , 45.379033 GHz) emission line, using the Nobeyama 45 m telescope. The map shows that the TMC-1 filament has a diameter of ∼0.1 pc and a length of ∼0.5 pc at a distance of 140 pc. The position-velocity diagrams of CCS clearly indicate the existence of velocity-coherent substructures in the filament. We identify 21 substructures that are coherent in the position-position-velocity space by eye. Most of the substructures are elongated along the major axis of the TMC-1 filament. The line densities of the subfilaments are close to the critical line density for the equilibrium (∼17 M☉ pc−1 for the excitation temperature of 10 K), suggesting that self-gravity should play an important role in the dynamics of the subfilaments.