Millimeter molecular line and infrared observations of dense clouds associated with small Hα emission regions

A search for new sites of ongoing star formation was made using Hα emission nebulosity as a guide. The J = 1 → 0 transition of 12C16O (115 GHz) is used as a temperature probe of the structure of these regions and thus as an indicator of the position of heating sources embedded in these molecular clouds. Of the 60 Hα regions surveyed, 30 distinct areas of CO emission enhanced in one or more localized areas have been detected. Several are very strong molecular-emission sources and some appear to be quite simple in structure compared to the giant molecular cloud/HII region complexes most commonly discussed in the literature. A search for high-density cores of these new regions was made using three transitions of H2CO. The column density of the 13CO (110 GHz) isotopic species was used as a rough guide for the formaldehyde survey. Compact high-density cores were found in the six best candidates, with H2 densities estimated to be greater than 104 to 105 cm-3. At least five of the six high-density regions found in the formaldehyde survey contain embedded infrared sources. These sources were found by mapping at 2.2μ. For two of the new molecular clouds, S140 and S255, sufficient data are available to assess the relative importance of various heat inputs to the clouds. Each cloud contains only one embedded source and two external stars. The gas kinetic temperature contour maps, obtained from detailed 12C16O observations, are then used to predict the dust cooling flux through far-infrared radiation and gas cooling through 12C16O radiation. The predicted far-infrared emission greatly exceeds the cooling by molecular lnes. This far-infrared flux should be observable