First detection of submillimeter [C I] emission in the small magellanic cloud

We report the first detection of [C I] (P-3(1) --> P-3(0)) emission at 609 mu m in a region of the Small Magellanic Cloud (N27). Environments poor in heavy elements and dust such as the SMC are thought to be dominated by photodissociation regions (PDRs), This is the lowest metallicity source where submillimeter neutral carbon emission has been detected. Studying the I-[CI]\I-CO ratio in several sources spanning more than an order of magnitude in metallicity Z, we find that the I-[CI]\I-CO ratio increases for decreasing Z. The existence of such a trend points to a photodissociation origin for most of the neutral carbon in molecular clouds, in agreement with standard PDR models. We also report Infrared Space Observatory far-infrared (FIR) spectroscopic observations of N27 and use them to derive its physical properties. Comparison between the density and radiation field revealed by FIR diagnostics (n similar to 300-1000 cm(-3), chi(uv) similar to 30 chi(0)-100 chi(0)) and those derived from millimeter and submillimeter data (n similar to 10(5) cm(-3), chi(uv) greater than or similar to 30 chi(0)) suggests that the FIR lines originate in more diffuse gas and are perhaps dominated by the interclump medium. Regardless of the cause, analysis of the FIR and millimeter-submillimeter data produces a discrepancy of 2 orders of magnitude for the density of this source.