The disk-outflow system in the S255IR area of high mass star formation
  We report the results of our observations of the S255IR area with the SMA at
1.3 mm in the very extended configuration and at 0.8 mm in the compact
configuration as well as with the IRAM-30m at 0.8 mm. The best achieved angular
resolution is about 0.4 arcsec. The dust continuum emission and several tens of
molecular spectral lines are observed. The majority of the lines is detected
only towards the S255IR-SMA1 clump, which represents a rotating structure
(probably disk) around the young massive star. The achieved angular resolution
is still insufficient for conclusions about Keplerian or non-Keplerian
character of the rotation. The temperature of the molecular gas reaches 130-180
K. The size of the clump is about 500 AU. The clump is strongly fragmented as
follows from the low beam filling factor. The mass of the hot gas is
significantly lower than the mass of the central star. A strong DCN emission
near the center of the hot core most probably indicates a presence of a
relatively cold ($\lesssim 80$ K) and rather massive clump there. High velocity
emission is observed in the CO line as well as in lines of high density tracers
HCN, HCO+, CS and other molecules. The outflow morphology obtained from
combination of the SMA and IRAM-30m data is significantly different from that
derived from the SMA data alone. The CO emission detected with the SMA traces
only one boundary of the outflow. The outflow is most probably driven by jet
bow shocks created by episodic ejections from the center. We detected a dense
high velocity clump associated apparently with one of the bow shocks. The
outflow strongly affects the chemical composition of the surrounding medium.
