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J. H. Lacy, J. M. Scalo, M. J. Richter (University of Texas)
Double-peaked optically thick molecular line profiles with a blue asymmetry, combined with single-peaked optically thin lines along the same lines of sight have previously been interpreted in terms of gravitational collapse. We show that it is possible to obtain such profiles using a general velocity field with correlated fluctuations, without requiring gravitational collapse motions. The major assumption is that line excitation increases in regions of convergent flows. A simple model with a fractional Brownian noise velocity field is used as an illustration. We predict how the frequency distribution of line profile skewness should depend on the exponent of the fractional Brownian noise. Comparison with line profiles taken through two-dimensional simulations of driven self-gravitating MHD turbulence will be used to understand the contribution of various physical effects to the predicted shapes of the profiles.
The author(s) of this abstract have provided an email address for comments about the abstract: lacy@astro.as.utexas.edu