Study of the filamentary infrared dark cloud G192.76+00.10 in the S254-S258 OB complex

Abstract

We present results of a high resolution study of the filamentary infrared dark cloud G192.76+00.10 in the S254-S258 OB complex in several molecular species tracing different physical conditions. These include three isotopologues of carbon monoxide (CO), ammonia (NH3) and carbon monosulfide (CS). The aim of this work is to study the general structure and kinematics of the filamentary cloud, and its fragmentation and physical parameters. The gas temperature is derived from the NH3 (J, K) = (1, 1), (2, 2) and 12CO(2-1) lines, and the 13CO(1-0), 13CO(2-1) emission is used to investigate the overall gas distribution and kinematics. Several dense clumps are identified from the CS(2-1) data. Values of the gas temperature lie in the range 10 - 35K, and column density N(H2) reaches the value 5.1 1022 cm-2. The width of the filament is of order 1 pc. The masses of the dense clumps range from ∼ 30 M o to ∼ 160 M o. They appear to be gravitationally unstable. Themolecular emission shows a gas dynamical coherence along the filament. The velocity pattern may indicate longitudinal collapse.