Carbon in the N159/N160 complex of the large Magellanic Cloud

We present a study of carbon in N159/N160, an H II region complex in the lo w-metallicity Large Magellanic Cloud. We have mapped this region, which com prises four distinct molecular clouds spanning a wide range of star formati on activity, in four transitions: (CO)-C-13 (J = 1 --> 0), (CO)-C-12 (J = 2 --> 1) and (J = 4 --> 3), and [C I] (P-3(1) --> P-3(0)). Combining these d ata with existing [C II] (P-2(3/2) --> P-2(1/2)) observations provides a co mplete picture of the predominant forms of carbon in the gas phase of the I SM. The new CO (J = 2 --> 1) data show that the complex is immersed in an e nvelope of extended, low-level emission, undetected by previous (J = 1 --> 0) mapping efforts. The (CO)-C-12 (J = 2 --> 1)/J = 1 --> 0) ratio in this envelope is greater than or similar to3, a value consistent with optically thin CO emission. The envelope is also relatively bright in [C I] and [C II ], and calculations show that it is mostly photodissociated: it appears to be translucent (A(v) < 1). Neutral carbon emission in the complex unexpecte dly peaks at the quiescent southern cloud (N159S). In the northern portion of the map (the N160 nebula), the H II regions prominent in [C II] correspo nd to holes in the [C I] distribution. Overall we find that, while the I-[C II]/I-CO ratio is enhanced with respect to similar complexes in the Milky W ay, the I-[CI]/I-CO ratio appears to be similar or reduced.