Turbulent Gas Flows in the Rosette and G216‐2.5 Molecular Clouds: Assessing Turbulent Fragmentation Descriptions of Star Formation

The role of turbulent fragmentation in regulating the efficiency of starformation in interstellar clouds is examined from new wide field imaging of12CO and 13CO J=1-0 emission from the Rosette and G216-2.5 molecular clouds.The Rosette molecular cloud is a typical star forming giant molecular cloud andG215-2.5 is a massive molecular cloud with no OB stars and very little low massstar formation. The properties of the turbulent gas flow are derived from theset of eigenvectors and eigenimages generated by Principal Component Analysisof the spectroscopic data cubes. While the two clouds represent quite divergentstates of star formation activity, the velocity structure functions for bothclouds are similar. The sonic scale, lambda_S, defined as the spatial scale atwhich turbulent velocity fluctuations are equivalent to the local sound speed,and the turbulent Mach number evaluated at 1 pc, M_{1pc}, are derived for anensemble of clouds including the Rosette and, G216-2.5 regions that span alarge range in star formation activity. We find no evidence for the positivecorrelations between these quantities and the star formation efficiency, thatare predicted by turbulent fragmentation models. A correlation does existbetween the star formation efficiency and the sonic scale for a subset ofclouds with L_{FIR}/M(H_2) > 1 that are generating young stellar clusters.Turbulent fragmentation must play a limited and non-exclusive role indetermining the yield of stellar masses within interstellar clouds.Comment: Accepted by ApJ, 22 pages, 7 figure