HIGH-RESOLUTION OBSERVATIONS OF TURBULENCE IN THE SUBCONDENSATION TMC-1C IN HEILES CLOUD 2 - ESTIMATION OF THE VELOCITY SPECTRUM OF TURBULENCE

We have made mapping observations of 4' x 4' and 8' x 8' areas of the subcondensation TMC-IC in Heiles' cloud 2 of the Taurus complex (140 p c) by using the 45 m telescope of Nobeyama Radio Observatory. The (CO) -C-13(j = 1-0) and (CO)-O-18(J = 1-0) lines were used and the beam siz e of the telescope was almost-equal-to 17' (0.01 pc). From the raw dat a in each area we could extract fluctuating components whose wavelengt hs range from twice the grid spacing for our mapping to the size of ou r observed area, and the components are considered as turbulence in th is study. We have evaluated unbiased autocorrelation functions (ACFs) of turbulent velocity and intensity fields from the (CO)-C-13 and (CO) -O-18 data, respectively, and the ACFs show meaningful correlations in the turbulent velocity and intensity fields. Based on the ACFs in the 4' x 4' area we have estimated power spectra by a two-dimensional max imum entropy method. The velocity spectrum, equivalent to the lateral three-dimensional spectrum, does not decrease monotonically in proport ion to the wavenumber, but increases in the range from 1/(0.05 pc) to 1/(0.03 pc), unlike Kolmogorov's 5/3 law. This feature indicates that the energy of the lateral part of turbulence per unit mass concentrate s at the scales of less than or similar to 0.03 pc, and that the energ y dissipation does not occur at such small scales. Besides, the spectr um seems to have a peak at 0.15 pc, because turbulent motions having s cales larger than approximately 0.15 pc are removed as ordered motions in our analysis.