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Paper: Infrared Dark Clouds
Volume: 387, Massive Star Formation: Observations Confront Theory
Page: 44
Authors: Jackson, J.M.; Chambers, E.T.; Rathborne, J.M.; Simon, R.; Zhang, Q.
Abstract: Infrared Dark Clouds are identified as deep extinction features against the Galactic mid-infrared background. Through 13CO and CS observations, we have determined kinematic distances to over 500 IRDCs. We find characteristic sizes of several pc and masses of a few thousand M, comparable to cluster-forming molecular clumps like Orion and Ophiuchus. Millimeter continuum images show that IRDCs contain compact cores with sizes <0.5 pc and masses ∼100 M. About 1/3 of these cores show unambiguous evidence for active star formation, such as outflows, high densities, broad lines, evidence for shocks, and ‘hot core’ chemistry. Several have luminosities >10,000 L, conclusively demonstrating that they contain high-mass protostars. Interferometeric images often reveal binary or multiple protostellar systems, indicating cluster formation. The ‘quiescent’ IRDC cores are probably high-mass ‘starless cores’.
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