Published online by Cambridge University Press: 14 August 2015
Observations have revealed the presence of inhomogeneities in both density and velocity in Hiiregions. Dense non-ionized condensations can persist for a long time, developing bright rims of dense ionized gas around them. Attempts have been made to understand the large ~50 km s-1 motions seen in some Hiiregions by invoking stellar winds or the flow of cosmic ray particles through the plasma.