Density studies of giant extragalacticHII regions

We have studied the variation of the electron density with position in a selected group of bright giant extragalacticHII regions with the use of long slit spectrophotometry at high spectral and spatial resolution. Density values for the ionized gas of the regions have been obtained from the measurement of the SII] 6717, 6731 ratio. We conclude that the regions are not homogeneous; the density varies with position, with the zones of high density frequently associated to high surface brightness.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.