(Abridged) Aims. We intend to derive statistical properties of stochastic gas
motion inside the dense low mass star forming molecular cores traced by
NH3(1,1) and (2,2) emission lines. Methods. We use the spatial two-point
autocorrelation (ACF) and structure functions calculated from maps of the
radial velocity fields. Results. We find oscillating ACFs which eventually
decay to zero with increasing lags on scales of 0.04 <= l <= 0.5 pc. The
current paradigm supposes that the star formation process is controlled by the
interplay between gravitation and turbulence, the latter preventing molecular
cores from a rapid collapse due to their own gravity. Thus, oscillating ACFs
may indicate a damping of the developed turbulent flows surrounding the dense
but less turbulent core - a transition to dominating gravitational forces and,
hence, to gravitational collapse.Comment: 11 pages, 16 figures, 3 tables, to be published in Astronomy and
Astrophysic
