Key points are not available for this paper at this time.
Observations of (C-13)O J = 6 yields 5 emission from a variety of galactic star-forming regions are reported. Sources spanning a luminosity range of six orders of magnitude were observed in this transition. These observations confirm the existence of large amounts of warm, dense, quiescent molecular gas in most Galactic star-forming regions. Mid-J lines of (C-12)O are very optically thick. The lower limit to the kinetic gas temperature is around 100 K. Typical column densities in the warm gas components are as high as 10 exp 23/sq cm or higher. The molecular hydrogen densities are high enough to keep the mid-J CO level population close to thermalized. The new measurements provide further evidence that the warm, dense, quiescent gas found in star formation regions is most likely to be heated by the energetic UV radiation escaping the H II regions around young stars.
Graf et al. (Mon,) studied this question.