Structure of the W40 cloud and small-scale clumpiness in high-mass star-forming regions

I will give the results of millimeter molecular line and dust continuum study of the dense cloud associated with W40, one of the nearby HII regions. The results of the GMRT decimeter observations will also be given. The cloud consists of the clumpy dust ring and an extended molecular region. There are sharp differences in morphologies of dust and molecular gas. Physical parameters of the dust clumps and molecular gas have been obtained. The clumps which are close to the main HII region are probably more evolved than the others showing signs of ongoing star formation which is probably triggered by the ionized front expanding into the cloud. In the second part of the talk I will give some indirect evidences for an existence of small-scale clumpy structure in several high-mass star-forming regions based on the analysis of line profiles obtained with high signal-to-noise ratios. The results of the calculations within the framework of the model consisted of an ensemble of clumps having low volume filling factor and moving with random velocities in the inter-clump media are given. The physical parameters of probable small-scale clumpy structure are derived and discussed.