Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear Hydromagnetic Wave Support of a Stratified Molecular Cloud II:
  A Parameter Study   We use numerical simulations to study the effect of nonlinear MHD waves in a
stratified, self-gravitating molecular cloud that is bounded by a hot and
tenuous external medium. In a previous paper, we had shown the details of a
standard model and studied the effect of varying the dimensionless amplitude.
In this paper, we present the results of varying two other important free
parameters: beta_0, the initial ratio of gas to magnetic pressure at the cloud
midplane, and the dimensionless frequency of driving. Furthermore, we present
the case of a temporally random driving force. Our results demonstrate that a
very important consideration for the actual level of turbulent support against
gravity is the ratio of driving wavelength lambda_0 to the the size of the
initial non-turbulent cloud; maximum cloud expansion is achieved when this
ratio is close to unity. The best consistency with the observational
correlation of magnetic field strength, turbulent line width, and density is
achieved by cloud models with beta_0 approx 1. We also calculate the spatial
power spectra of the turbulent clouds, and show that significant power is
developed on scales larger than the scale length H_0 of the initial cloud, even
if the input wavelength of turbulence lambda_0 approx H_0. The cloud
stratification and resulting increase of Alfven speed toward the cloud edge
allows for a transfer of energy to wavelengths significantly larger than
lambda_0. This explains why the relevant time scale for turbulent dissipation
is the crossing time over the cloud scale rather than the crossing time over
the driving scale.

25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an