The [OI] fine structure line profiles in Mon R2 and M17 SW: the puzzling nature of cold foreground material identified by [12CII] self-absorption

C. Guevara, J. Stutzki V. Ossenkopf-Okada, U. Graf +8

Context. Recent studies of the optical depth comparing [12CII] and [13CII] line profiles in Galactic star-forming regions revealed strong self-absorption in [12CII] by low excitati…