期刊
ASTRONOMY & ASTROPHYSICS
卷 531, 期 -, 页码 -出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/201016336
关键词
ISM: clouds; galaxies: ISM; Magellanic Clouds; infrared: ISM; dust, extinction
资金
- NASA [NAGW-4454, 1394366]
- NSF [AST-0705157]
- Netherlands Organisation for Pure Research (N.W.O.)
Context. We study the lambda 158 mu m [C II] fine-structure line emission from star-forming regions as a function of metallicity. Aims. We have measured and mapped the [C II] 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. Methods. In both LMC and SMC, the ratio of [C II] 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. Results. 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 [C II] 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 [C II] strengths are high but exhibit little further dependence on actual metallicity. Relative [C II] strengths are slightly higher in the LMC than in the SMC which has both lower dust and lower PAH abundances.
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