Low Mass Clumps in TMC-1: Scaling Laws in the Small Scale Regime

We present new observational data on the small scale structure of the Taurus Molecular Cloud 1 (TMC-1) in the regime of 0.02-0.04 PC and 0.04 -0.6 Mo. Our analysis is based on high resolution, high signal-to-noise, observations of an 8’x8’ area centered on the “cyanopolyyne peak” in the SE part of the TMC-1 ridge. The observations were made in the CCS 22 GHz and 45 GHz transitions using NASA’s Deep Space Network 70-m and 34-m telescopes at the Goldstone facility. The CCS emission in this region originates in three narrow components centered on LSR velocities of -5.7, 5.9, and 6.1 km S–l. These components each represent a separate cylindrical feature elongated along the ridge. Among the three velocity components we identified a total of 45 clumps with a typical CCS column density of w few x1013 cm-2, an H2 density of w few x104 cm -3, and a mass in the range of 0.04 to 0.6 MO. The statistical properties of these small scale clumps are compared with those of the larger ‘(NH3 cores” in cold clouds and ‘(CS cores” in the hotter Orion region. The CCS clumps in TMC-1 are found to conform to the Larson’s scaling laws (relating observed linewidth to clump size) derived from the larger cores down to the small scale regime (0.02 pc and 0.04 Mo). These clumps represent a regime where microturbulence is small, amounting to ~10~0 of the thermal pressure inside a clump. Of the 45 clumps, only five appear to be gravitationally unstable to collapse. The 6.1 km S-l component contains all the gravitationally unstable clumps and is the most likely site for future star formation. Subject headings: ISM: clouds ISM: individual (Taurus Molecular Cloud) ISM: molecules stars: formation radio lines: ISM