Helium and Hydrogen Line Ratios and The Stellar Content of Compact HII Regions

We present observations and models of the behaviour of the HI and HeI lines between 1.6 and 2.2μm in a small sample of compact HII regions. As in our previous papers on planetary nebulae, we find that the ‘pure’ 1.7007μm 4D–3P and 2.16475μm 7G–4F HeI recombination lines behave approximately as expected as the effective temperature of the central exciting… CONTINUE READING