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 the 1.3 mm continuum and in several molecular line transitions were performed in the compact (2"4 angular resolution) and very-extended (similar to 0"4 angular resolution) configurations. The continuum emission from the compact configuration shows a dust core of 150M(circle dot), while the very-extended configuration reveals a dense (2.6 x 107 cm(-3)) and compact (similar to 4000 au) condensation of 8M(circle dot). 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 (CO)-C-12(2 - 1), (CO)-C-13(2 - 1), and SO(6(5)- 5(4)) lines reveal a molecular outflow at PA similar to 135 degrees centered at the continuum peak. The extended (CO)-C-12(2 - 1) emission has been recovered with the IRAM 30 m telescope observations. Using the combined data set, we derive an outflow mass of 16.8M(circle dot). 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.