Rotation of the Warm Molecular Gas Surrounding Ultracompact HII Regions
  We present molecular line and 1.4 mm continuum observations towards five
massive star forming regions at arcsecond resolution using the Submillimeter
Array (SMA). We find that the warm molecular gas surrounding each HII region
(as traced by SO_2 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 HII region and find that this mass,
when added to the derived gas mass, is a significant fraction of the dynamical
mass for that region.
