THE PROPERTIES OF NARROW RECOMBINATION LINE HII REGIONS

we propose to study farinfrared line and continuum emission from hii regions with unusually narrow radio recombination lines. compared with most star forming regions, these objects require both very low electron temperature (t_e<virgul4600 k) and small nonthermal line broadening in the ionized gas. the low temperatures could be the result of high abundances, low electron density, and/or low effective stellar temperature. the origin of the lack of nonthermal broadening is more speculative, but may be produced by low density and the absence of density gradients and stellar winds. by probing both the ionized gas and the adjacent photodissociated material, the proposed fir line measurements (siii (33 microns), siv (10.5 microns), and siii (35 microns)) together with measurements already obtained during calibration of the lws (oiii (52 and 88 microns), niii 57 microns), oi (63 and 146 microns), nii (122 microns), and cii (158 microns), and the 43173 micron continuum) on the same objects will determine the physical conditions which are responsible for the low temperature and the lack of nonthermal line broadening. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]