In the subsection “PAHs in Other PDRs, PNe, and RNe,” you first state that the presence of PAHs in oxygen-rich planetary nebulae (mixed-chemistry objects) supports the hypothesis that “PAHs can be formed outside of what would be the CO photodissociation front.” However, in the immediately following paragraph, you cite the same authors’ later work and conclude that the observed distribution of material “favor[s] the recent dredge-up as the explanation for the double chemistry in this object.” These appear to be two competing interpretations for the same set of observations. If the formation mechanism for PAHs in these mixed-chemistry environments is still unresolved and subject to contradictory explanations, how does this affect the overall narrative regarding PAH formation pathways and chemical evolution in evolved stellar systems? Could this ambiguity undermine the conclusions drawn in later sections that build upon these formation scenarios?
