33.8 GHz CCS survey of molecular cores in dark clouds

We have conducted a survey of the CCS J(N) = 3(2)-2(1) line toward 11 dark clouds and star-forming regions at 30 " spatial resolution and 0.054 km s(- 1) velocity resolution. CCS was detected only in quiescent clouds, not in a ctive star-forming regions. The CCS distribution shows remarkable clumpy st ructure, and 25 clumps are identified in seven clouds. Seven clumps with ex tremely narrow nonthermal line widths (<0.1 km s(-1)) are among the most qu iescent clumps ever found. The CCS clumps tend to exist around the higher d ensity regions traced by NH3 emission or submillimeter continuum sources, a nd the distribution is not spherically symmetric. Variation of the CCS abun dance was suggested as an indicator of the evolutionary status of star form ation. However, we can only find a weak correlation between N(CCS) and n(H2 ,vir). The velocity distributions of CCS clouds reveal that a systematic ve locity pattern generally exists. The most striking feature in our data is a ring structure in the position-velocity diagram of L1544 with an well-reso lved inner hole of 0.04 pc x 0.13 km s(-1) and an outer boundary of 0.16 pc x 0.55 km s(-1). This position-velocity structure clearly indicates an edg e-on disk or ring geometry, and it can be interpreted as a collapsing disk with an infall velocity greater than or similar to 0.1 km s(-1) and a rotat ional velocity less than our velocity resolution. Nonthermal line width dis tribution is generally coherent in CCS clouds, which could be evidence for the termination of Larson's Law at small scales, similar to 0.1 pc.