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|Long-Slit Spectrophotometry of the H II Regions GUM 38a and GUM 38b|
We present new long-slit spectrophotometric observations in the range3700--7200 Angstroms of the H II regions Gum 38a and Gum 38b (RCW 57).We study the spatial distribution of reddening and excitation throughoutthe complex by means of emission-line intensities. From the strongreddening difference, we confirm that Gum 38a and Gum 38b are twoindividual complexes, the former being in the foreground. We derivechemical abundances in both nebulae, the results of which are similar tothose of the Orion Nebula. This is consistent with the fact that thethree nebulae are located at similar Galactocentric distances. We alsodiscuss the general ionization structure of the complexes based on thespectral properties of several filaments and diffuse emission around thecentral bright knots of Gum 38a and beyond. In particular, we found aninteresting filament with strong [O I] lambda lambda 6300, 6364 lines.