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We compare the physical properties of H II regions situated in galactic nuclei, in regions immediately surrounding the nuclei ("hotspots"), and in the disks, using optical spectrophotometry and radio-continuum data. The integrated properties (size, Hα luminosity) of the nuclei and hotspots are similar to those of the brightest disk H II regions, but we find important differences in the emission-line spectra, internal structure, and radio properties. Roughly half of the H II region and starburst nuclei show evidence for a secondary ionization component, either an active nucleus or large-scale shocks. This feature is seen both in the line ratios and line profiles. This supports the idea that many spiral nuclei are composite in nature, with a central LINER or Seyfert-like nucleus surrounded by star-forming regions. The combination of this complex ionization structure with extinction will hinder the interpretation of their spectra in terms of standard nebular models. Hotspots possess unusually high surface brightness but are comparable in luminosity to bright disk H II regions. Their most unusual property is a very strong stellar continuum (relative to the emission-line luminosity). This may reflect a long history of star formation in the same region or an unusual stellar mass spectrum in the ionizing clusters.
C. et al. (Sat,) studied this question.