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The Weakness Of Diffuse Bands In Nebular Environments. Possible Impact On Thepah+ Hypothesis, T P. Snow, E L. Bakes, R H. Buss Jr., C G. Seab

Physics Faculty Publications

It has been widely suggested that PAH cations (PAH+) may be the carriers of the diffuse interstellar bands, so it is of interest to probe diffuse behavior in regions suspected of having high abundances of PAHs. Here we examine the strengths of several of the visible-wavelength diffuse interstellar bands in two nebular environments where infrared emission and ultraviolet indicators show that PAHs are abundant. One might expect the PAHs to be predominantly positively ionized in these regions, yet the diffuse bands are systematically weak. This led us to examine the ionization balance for see whether the weakness of the diffuse …