Evidence for turbulence in \hii regions
C. R. O'Dell, H. O. Castaneda;
ApJ, 1987, 317, 686
ABSTRACT:The results of extensive velocity mapping across the face of Galactic H II regions are used to make an accurate determination of velocity
dispersions and structure functions for a number of nebulae.
A dependence of
random velocities upon scale, indicating the presence of turbulence, is
found.
These relationships are compared with the predictions of models for
Kolmogorov turbulence in H II regions, and poor agreement is found.
A more general
formulation shows that there is no single power law for the velocity-distance
relation that fits the observations.
From the variations in the shape of the
observed structure function, it is concluded that the turbulent energy enters
the nebulae at several different scales.
It is also found that velocity
broadening of the observed lines is significantly greater than would be inferred
from the velocity scatter across the face of the nebulae.
KEYWORDS: gas dynamics, h ii regions, nebulae, turbulence, velocity distribution, astronomical models, kolmogoroff theory
PERSOKEY:region hii, turbulence, ,
CODE: odell87