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Astron. Astrophys. 353, 339-348 (2000)

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Characterizing the structure of interstellar turbulence

M.-M. Mac Low *  1 and V. Ossenkopf 2

1 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
2 1. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany

Received 10 May 1999 / Accepted 11 October 1999


Modeling the structure of molecular clouds depends upon good methods to statistically compare simulations with observations in order to constrain the models. Here we characterize a suite of hydrodynamical and magnetohydrodynamical (MHD) simulations of supersonic turbulence using an averaged wavelet transform, the [FORMULA]-variance, that has been successfully used to characterize observations. We find that, independent of numerical resolution and dissipation, the only models that produce scale-free, power-law [FORMULA]-variance spectra are those with hypersonic rms Mach numbers, above [FORMULA], while slower supersonic turbulence tend to show characteristic scales and produce non-power-law spectra. Magnetic fields have only a minor influence on this tendency, though they tend to reduce the scale-free nature of the turbulence, and increase the transfer of energy from large to small scales. The evolution of the characteristic length scale seen in supersonic turbulence follows exactly the [FORMULA] power-law predicted from recent studies of the kinetic energy decay rate.

Key words: hydrodynamics – Magnetohydrodynamics (MHD) – turbulence – ISM: clouds – ISM: kinematics and dynamics – ISM: structure

* Current Address: Department of Astrophysics, American Museum of Natural History, 79th Street at Central Park West, New York, NY 10024-5192, USA

Send offprint requests to: V. Ossenkopf (ossk@zeus.ph1.uni-koeln.de)

© European Southern Observatory (ESO) 2000

Online publication: December 8, 1999