THE H-II REGION SHARPLESS-170 - A MULTISCALE ANALYSIS OF THE H-ALPHA VELOCITY-FIELD

A total of 12,695 Her radial velocities were measured across the H II region Sh 170 using a Fabry-Perot camera. The mean V-LSR of the ionize d gas is -50.10 +/- 0.08 km s(-1) with a velocity dispersion of 8.70 /- 0.05 km s(-1). Sh 170 has a blueshift of 6.4 km s(-1) with respect to the associated molecular cloud. The nebula is density bounded on al l visible sides, indicating that the H II region is seen in front of t he molecular cloud. The velocity field can be explained as an expansio n of the ionized gas away from the molecular cloud toward the observer . A north-south velocity gradient of 1.4 km s(-1) pc is also observed. The locus of the less negative velocity (V-LSR approximate to -45 km s(-1)) coincides with the molecular cloud's position. Several kinemati cal and morphological aspects of Sh 170 are in good agreement with the ''Champagne'' phase model. Sh 170 has a similar to 2 pc cavity devoid of ionized gas approximately centered on the ionizing star which can be explained by the action of a stellar wind. The large number of velo city measurements allowed a systematic analysis of velocity fluctuatio ns in Sh 170. The relation between centroid velocity dispersion sigma( c) and scale l was derived. The two-point autocorrelation (C) and stru cture (S) functions were used; these are reliable tools for the invest igation of the statistical properties of fluctuating gas motions. It w as found that velocity correlation occurs at scales smaller than 0.7 p c in Sh 170. The e-folding length of the autocorrelation function (the correlation length) is 0.03 +/- 0.02 pc, and a power-law relation bet ween S and scale was obtained: S(tau) proportional to tau(0.8+/-0.1). An interpretation of these results in terms of turbulence is presented .