ROTATION OF THE WARM MOLECULAR GAS SURROUNDING ULTRACOMPACT H ii REGIONS

We present molecular line and 1.4 mm continuum observations toward five massive star-forming regions at arcsecond resolution using the Submillimeter Array. We find that the warm molecular gas surrounding each H ii region (as traced by SO2 and OCS) appears to be undergoing bulk rotation. From the molecular line emission and thermal component of the continuum emission, we independently derived gas masses for each region which are consistent with each other. From the free–free component of the continuum emission, we estimate the minimum stellar mass required to power the H ii region and find that this mass, when added to the derived gas mass, is a significant fraction of the dynamical mass for that region.