Abstract
We report VLA observations of 8.3 GHz continuum and H92 α radio recombination line towards the star forming regions G34.26+0.15 and G5.89-0.39. Both regions show considerable mean optical depth in the continuum at 8.3 GHz, τc ~= 2 , and the H92 α line can be used to study opacity variations across the face of the nebula. We detected H92 α emission in the ultracompact component A of G34.26+0.15, but not in the ultracompact component B. This result is puzzling since both ultracompact components are similar in continuum flux density and angular size. G5.89-0.39 shows strong velocity gradients in the H92 α line, but these cannot be attributed only to rotation, as previously proposed.
