2011A&A...531A..19I

We study the λ 158 µm [CII] fine-structure line emission from star-forming regions as a function of metallicity. We have measured and mapped the [CII] emission from the very bright HII region complexes N 11 in the LMC and N 66 in the SMC; as well as the SMC HII regions N 25, N 27, N 83/N 84, and N 88 with the FIFI instrument on the Kuiper Airborne Observatory. In both LMC and SMC, the ratio of [CII] line to CO line and to the far-infrared continuum emission is much higher than seen almost anywhere else, including Milky Way star-forming regions, and whole galaxies. In the low metallicity, low dust-abundance environment of the LMC and the SMC UV mean free path lengths are much greater than those in the higher-metallicity Milky Way. The increased photoelectric heating efficiencies cause significantly greater relative [CII] line emission strengths. At the same time, similar decreases in PAH abundances have the opposite effect by diminishing photoelectric heating rates. Consequently, in low-metallicity environments relative [CII] strengths are high but exhibit little further dependence on actual metallicity. Relative [CII] strengths are slightly higher in the LMC than in the SMC which has both lower dust and lower PAH abundances.