HIGH-RESOLUTION (CO)-O-17 OBSERVATIONS OF M17SW .3. ANALYSIS OF DENSITY AND VELOCITY STRUCTURE

In an earlier paper, we presented an analysis of the small-scale struc ture of the M17SW molecular cloud based on observations of the optical ly thick HCO+ and HCN J = 3 --> 2 transitions. In this paper we presen t observations of the (CO)-O-17 J = 3 --> 2 transition. This transitio n is optically thin, is observed with a slightly smaller beam, and suf fers less from confusion by cool gas; as a result it should be a bette r tracer of the kinematics of the warm molecular gas in the region. We analyse the structure using the same techniques as in Paper I, and fi nd that our earlier results are confirmed by these new data. In partic ular, we identify 35 individual clumps, with masses ranging from 10-10 00 M.. The clump mass spectrum has a slope of -1.9 +/- 0.2, which is i dentical to our earlier value. Autocorrelation and structure function analysis of the velocity centroid map confirms the presence of small-s cale, nearly isotropic motion with a characteristic scale of almost-eq ual-to 0.2 pc; the variation with scale of the turbulent pressure and energy dissipation rate are similar to those derived for the HCO+ and HCN data. The Gaussian-clump decomposition is broadly similar to that for (CO)-O-18 J = 2 --> 1 by Stutzki & Gusten, within the area common to both maps, but differs greatly from that for HCO+ and HCN. Thus, al though clump fitting is a useful formal description of structure, it i s only an approximate description of real (non-Gaussian) molecular clo ud components.