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Comprehensive studies of isolated low mass star forming cores have greatly enhanced our understanding of the structure and evolution of these objects. Most star formation, however, occurs in clustered environments, which are characterized by more complex geometries and kinematics. In this detailed study, we present combined single-dish and interferometric NH3 (1,1) and (2,2) observations in the Oph B, C and F filaments in the cluster-forming Ophiuchus molecular cloud. We find surprising differences in the physical properties of the filaments. Dense gas in Oph B is extremely 'clumpy', but kinetic temperatures vary little and are warmer than those observed in isolated cores, and over most of the filament non-thermal motions dominate the observed linewidths. Several localized emission peaks are associated with higher NH3 column density, near-thermal linewidths and moderately cooler gas temperatures. In contrast to isolated cores, however, these NH3 peaks are not coincident with the millimeter continuum emission peaks. Conversely, in Oph C, the NH3 and dust continuum emission correlate well. In addition, we find Oph C is significantly colder than Oph B, with near-thermal linewidths. Oph F is warmer than both Oph B and C, and shows complicated velocity structure possibly caused by embedded protostars. Additional single-dish detections of transitions from the early-time molecules CCS and HC5N provide evidence that Oph C may be in a younger evolutionary state than B or F.
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