Observations of major ionization fronts in M42 and M8

Image tube filter photographs taken in the light of the low ionization energy Nii] and high ionization energy Oiii] lines of the core of M42 are presented. These were taken with the 98-in. Isaac Newton telescope. The whole core of M42 appears to be a complex of ionization fronts. An Nii] photograph of M8 also suggests that the whole of this Hii region is composed of a mass of fronts penetrating into a huge neutral region containing dust, gas and molecules.