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S. Gezari (Brown Univ. \& Maria Mitchell Obs.), M.J. Reid (Harvard-Smithsonian Center for Astrophysics), V. Strelnitski (Maria Mitchell Obs.)
Supersonic turbulence as traced by water vapor masers was investigated in five sources associated with outflows from young stars: W49N, W51N, W51MAIN, W3(OH), and ORION-KL. Statistical properties of the spatial structure and velocity field of the sources were analyzed using published VLBI water maser maps. All of the five sources demonstrate a power-law dependence of two-point velocity difference on point separation and a fractal spatial distribution --- a power-law dependence of surface density of companions to a point on distance to the companions. These two properties are known as typical of turbulent media. The exponent of the velocity-separation power law is close to its classical Kolmogorov value 1/3 for four out of five of the sources. ORION-KL is the only exception, and reasons for this are discussed. The exponent of the surface density-separation power law indicates a low fractal dimension (less than 1) in all five of the sources. These results confirm our previous conclusions, based on the analysis of W49N and SgrB2M (Alexander et al. 1998, Holder et al. 1998), that (1) the water masers are imbedded in a turbulent medium and, most probably, originate at the sites of enhanced dissipation of turbulent energy, and (2) supersonic turbulence as traced by the water masers is characterized by a Kolmogorov velocity-separation correlation function and a low fractal dimension. The combination of these two statistical properties puts strong constraints on the existing theories of turbulence.
The author(s) of this abstract have provided an email address for comments about the abstract: Suvi_Gezari@Brown.edu