The small-scale density and velocity structure of quiescent molecular clouds
E. Falgarone, J. L. Puget, M. Perault;
AaA, 1992, 257, 715
ABSTRACT:Using an ensemble of maps in rotational transitions of CO isotopic variants, obtained in a variety of clouds, the features of the link between the
velocity and density fields in molecular gas little contaminated by star
formation activity were identified.
The paradoxical role played by a turbulent
velocity field, predicted to generate density fluctuations and to stabilize
the unstable masses against gravitational collapse, is analyzed.
It is
shown that 32 structures isolated in the (l, b, v) data cubes of five different
clouds trace concentrations of gas, without prejudice to their own internal
density structure.
The results obtained on small-scale structures are
combined with those on larger structures drawn from previous work and the
literature, with the resulting ensemble covering a range of sizes and average
densities large enough to reveal new properties of the scaling laws between cloud
characteristics.
The results suggest that the velocity field is able to generate
inhomogeneities in the mass distribution of molecular clouds and that, up to some
threshold, this distribution is independent of self-gravity.
KEYWORDS: density distribution, gravitational collapse, interstellar gas, molecular clouds, abundance, carbon monoxide, interstellar matter, molecular gases, molecular rotation
CODE: falgarone92a