UNVEILING A NETWORK OF PARALLEL FILAMENTS IN THE INFRARED DARK CLOUD G14.225–0.506

Abstract

We present the results of combined NH3(1,1) and (2,2) line emission observed\nwith the Very Large Array and the Effelsberg 100m telescope of the Infrared\nDark Cloud G14.225-0.506. The NH3 emission reveals a network of filaments\nconstituting two hub-filament systems. Hubs are associated with gas of\nrotational temperature Trot \\sim 25 K, non-thermal velocity dispersion ~1.1\nkm/s, and exhibit signs of star formation, while filaments appear to be more\nquiescent (Trot \\sim 11 K, non-thermal velocity dispersion ~0.6 km/s).\nFilaments are parallel in projection and distributed mainly along two\ndirections, at PA \\sim 10 deg and 60 deg, and appear to be coherent in\nvelocity. The averaged projected separation between adjacent filaments is\nbetween 0.5 pc and 1pc, and the mean width of filaments is 0.12 pc. Cores\nwithin filaments are separated by ~0.33 pc, which is consistent with the\npredicted fragmentation of an isothermal gas cylinder due to the 'sausage'-type\ninstability. The network of parallel filaments observed in G14.225-0.506 is\nconsistent with the gravitational instability of a thin gas layer threaded by\nmagnetic fields. Overall, our data suggest that magnetic fields might play an\nimportant role in the alignment of filaments, and polarization measurements in\nthe entire cloud would lend further support to this scenario.\n