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

Abstract

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.