VELOCITY COHERENCE IN DENSE CORES

By analyzing the dependence of line width on size in NH3 maps of dense cores, and in (CO)-O-18 and OH maps of the gas around the cores, we f ind that: (1) on scales larger than the FWHM contour of an NH3 core, l ine width is correlated with size such that Delta nu proportional to R -a where a similar to 0 2; and (2) within the cores themselves, the po wer-law slope of the line width-size relation goes to zero (i.e., line width is constant). We interpret this result as evidence for a breakp oint between ''turbulent'' self-similar molecular clouds and ''velocit y coherent cores'' which can collapse to form individual stars or smal l groups of stars.