He II emission in extragalactic H II regions

摘要: Spectroscopic observations confirming the presence of nebular He II 4686-A emission in SMC H region N76 are presented, and it is demonstrated that associated with WO star IC 1613 also extended. The properties four regions discussed. close correlation specific stars indicates photoionization by themselves excitation mechanism, proposed this may be true for those nebulae ionized some rare high-excitation WN stars. existence these increases likelihood frequently observed dwarf emission-line galaxies origin. This prompts conclusion radiation field star-forming can harder than previously suspected, reopens issue whether young account ionization QSO absorption-line systems. 42 refs.