Study of Molecular Clouds associated with HII Regions
  The properties of molecular clouds associated with 10 HII regions were
studied using CO observations. We identified 142 dense clumps within our sample
and found that our sources are divided into two categories: those with clumps
that show a power law size-line width relation (Type I) and those which do not
show any relation (Type II). The clumps in the Type I sources have larger power
law indices than found in previous studies. The clumps in the Type II sources
have larger line widths and show evidence (such as outflows) of current active
star formation within the clump. We suggest that the lack of a size-line width
relation is a sign of current active star formation. Massive clumps seem to
have similar masses calculated by different methods but lower mass clumps have
larger virial masses compared to velocity integrated and LTE mass. We found no
relation between mass distribution of the clumps and distance from the H~II
region ionization front, but a weak decrease of the excitation temperature with
increasing distance from the ionized gas. The clumps in collected shells around
the H~II regions have slightly larger line widths but no relation was found
between line width and distance from the H~II region, which probably indicates
that the internal dynamics of the clumps are not affected by the ionized gas.
Internal sources of turbulence, such as outflows and stellar winds from young
proto-stars may have a more important role on the molecular gas dynamics. We
suggest that large line width and larger size-line width power law indices are
therefore the initial characteristics of clumps in massive star forming clouds
and that some may evolve into objects similar to our Type II sources, where
local "second generation" stars are forming and eliminating the size-line-width
relation.
