We have mapped the large-scale distribution of the 492 GHz (C I) (3P1 to 3P0) and 220 GHz (13)CO J = 2 to 1 lines across the S140 molecular cloud. The observations employed the University of Texas Gaussian Focal Reducer on the Caltech Submillimeter Observatory telescope to produce a high surface accuracy off-axis telescope with a 3 min beam. The (C I) emission covers a greater than or equal to 8 by approximately 10 pc region which closely matches the extent of the S140 molecular cloud as seen in (13)CO. The line shapes of (C I) and (13)CO are also quite similar. Typical column densities of C0 are approximately 15 times those of (13)CO. In this source, the neutral carbon emission most likely arises in the photon-dominated surface layers of molecular clumps. The layer in which C0 is the dominant form of gaseous carbon contains greater than or equal to 20% of all the neutral material in the extended cloud. The ratio of the (C I) (3P1 to 3P0) to CO J = 2 to 1 cooling integrated over the cloud is approximately 1.3, similar to the global value of this ratio in our Galaxy and to the value in the inner 100 pc of IC 342 and M82.
No takes yet. Share an insight, caveat, or question.
Plume et al. (1994) studied this question.