The Rotating Molecular Structures and the Ionized Outflow Associated
  with IRAS 16547-4247
  We present VLA 1.3 cm radio continuum and water maser observations as well as
SMA SO$_2$ (226.300 GHz) and 1.3 mm dust continuum observations toward the
massive star formation region IRAS 16547-4247. We find evidence of multiple
sources in the central part of the region. There is evidence of a rotating
structure associated with the most massive of these sources, traced at small
scales (~50 AU) by the water masers. At large scales (~1000 AU) we find a
velocity gradient in the SO2 molecular emission with a barely resolved
structure that can be modeled as a rotating ring or two separate objects. The
velocity gradients of the masers and of the molecular emission have the same
sense and may trace the same structure at different size scales. The position
angles of the structures associated with the velocity gradients are roughly
perpendicular to the outflow axis observed in radio continuum and several
molecular tracers. We estimate the mass of the most massive central source to
be around 30 solar masses from the velocity gradient in the water maser
emission. The main source of error in this estimate is the radius of the
rotating structure. We also find water masers that are associated with the
large scale molecular outflow of the system, as well as water masers that are
associated with other sources in the region. Our results suggest that the
formation of this source, one of the most luminous protostars or protostellar
clusters known, is taking place with the presence of ionized jets and disk-like
structures.
