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Description
We have investigated ~100 nearby molecular clouds using the extensive, all-sky database of IRAS. The clouds in this study cover a wide range of physical properties including visual extinction, size, mass, degree of isolation, homogeneity and morphology. IRAS 100 and 60 micrometre co-added images were used to calculate the 100 micrometre optical depth of dust in the clouds. These images of dust optical depth compare very well with ^12^CO and ^13^CO observations, and can be related to H_2_ column density. From the optical depth images we locate the edges of dark clouds and the dense cores inside them. We have identified a total of 43 "IRAS clouds" (regions with Av>2) which contain a total of 255 "IRAS cores" (regions with Av>4) and we catalog their physical properties. We find that the clouds are remarkably filamentary, and that the cores within the clouds are often distributed along the filaments. The largest cores are usually connected to other large cores by filaments. We have developed selection criteria to search the IRAS Point Source Catalog for stars that are likely to be associated with the clouds and we catalog the IRAS sources in each cloud or core. Optically visible stars associated with the clouds have been identified from the Herbig and Bell catalog. From these data we characterize the physical properties of the clouds including their star-formation efficiency.
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