IRAS IMAGES OF NEARBY DARK CLOUDS

We have investigated similar to 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, m ass, degree of isolation, homogeneity and morphology. IRAS 100 and 60 mu m co-added images were used to calculate the 100 mu m optical depth of dust in the clouds. These images of dust optical depth compare ver y well with (CO)-C-12 and (CO)-C-13 observations, and can be related t o H-2 column density. From the optical depth images we locate the edge s of dark clouds and the dense cores inside them. We have identified a total of 43 ''IRAS clouds'' (regions with A(upsilon) > 2) which conta in a total of 255 ''IRAS cores'' (regions with A(upsilon) > 4) and we catalog their physical properties. We find that the clouds are remarka bly filamentary, and that the cores within the clouds are often distri buted along the filaments. The largest cores are usually connected to other large cores by filaments. We have developed selection criteria t o 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 cl oud or core. Optically visible stars associated with the clouds have b een identified from the Herbig and Bell catalog. From these data we ch aracterize the physical properties of the clouds including their star- formation efficiency.