Synthesized spectra of turbulent clouds
E. Falgarone, D. C. Lis, T. G. Phillips, A. Pouquet, D. H. Porter, P. R. Woodward;
ApJ, 1994, 436, 728
ABSTRACT:A comparison has been made of the velocity structure of non-star-forming dense molecular clouds and the output of a 512(exp 3) hydrodynamic code
for compressible gas displaying features of turbulence.
A remarkable
similarity exists between the interstellar line profiles and the velocity
profiles found by integrating, with an optically thin assumption, through
subsections of the simulation.
This similarity is in terms of both the structure of
individual spectra, showing skewness, multiple peaks, and wings, and also the
variations of the spectra from point to point.
It is possible to see the origin of
the various velocity substructures and how they correlate with regions of
high density and velocity divergence, or regions of high vorticity, by
deprojecting individual spectra of the simulation.
It is found that the
interstellar medium spectra are best represented by the epoch of the simulation in
which the energy spectrum is essentially Kolmogorov-like and initially
developed shocks have been largely converted into vorticity
structures.
Further, it is found that the vorticity peaks ascribed to intermittency
contribute to the non-Gaussian features and wings of the line profile, but at an
intensity level that is weak compared to the contribution of the bulk of the flow.
KEYWORDS: compressible flow, gas dynamics, gas flow, interstellar gas, magnetohydrodynamic flow, molecular clouds, supersonic flow, velocity distribution, computerized simulation, flow velocity, kinematics, mathematical models, turbulence
PERSOKEY:turbulence, ,
CODE: falgarone94