SMA Observations of the Hot Molecular Core IRAS 18566+0408
  We present Submillimeter Array (SMA) observations toward the high-mass
star-forming region IRAS 18566+0408. Observations at 1.3 mm continuum and in
several molecular line transitions were performed in the compact (2."4 angular
resolution) and very-extended (~0."4 angular resolution) configurations. The
continuum emission from the compact configuration shows a dust core of 150
Msun, while the very-extended configuration reveals a dense (2.6 x 10^7 cm^-3)
and compact (~4,000 AU) condensation of 8 Msun. We detect 31 molecular
transitions from 14 species including CO isotopologues, SO, CH3OH, OCS, and
CH3CN. Using the different k-ladders of the CH3CN line, we derive a rotational
temperature at the location of the continuum peak of 240 K. The 12CO(2-1),
13CO(2-1), and SO(6_5-5_4) lines reveal a molecular outflow at PA ~135^o
centered at the continuum peak. The extended 12CO(2-1) emission has been
recovered with the IRAM 30 m telescope observations. Using the combined data
set, we derive an outflow mass of 16.8 Msun. The chemically rich spectrum and
the high rotational temperature confirm that IRAS 18566+0408 is harboring a hot
molecular core. We find no clear velocity gradient that could suggest the
presence of a rotational disk-like structure, even at the high resolution
observations obtained with the very-extended configuration.
