Dense Cores, Filaments and Outflows in the S255IR Region of High Mass
  Star Formation
  We investigate at a high angular resolution the spatial and kinematic
structure of the S255IR high mass star-forming region, which demonstrated
recently the first disk-mediated accretion burst in the massive young stellar
object. The observations were performed with ALMA in Band 7 at an angular
resolution $ \sim 0.1^{\prime\prime}$, which corresponds to $ \sim 180 $ AU.
The 0.9 mm continuum, C$^{34}$S(7-6) and CCH $N=4-3$ data show a presence of
very narrow ($ \sim 1000 $ AU), very dense ($n\sim 10^7$ cm$^{-3}$) and warm
filamentary structures in this area. At least some of them represent apparently
dense walls around the high velocity molecular outflow with a wide opening
angle from the S255IR-SMA1 core, which is associated with the NIRS3 YSO. This
wide-angle outflow surrounds a narrow jet. At the ends of the molecular outflow
there are shocks, traced in the SiO(8-7) emission. The SiO abundance there is
enhanced by at least 3 orders of magnitude. The CO(3-2) and SiO(8-7) data show
a collimated and extended high velocity outflow from another dense core in this
area, SMA2. The outflow is bent and consists of a chain of knots, which may
indicate periodic ejections possibly arising from a binary system consisting of
low or intermediate mass protostars. The C$^{34}$S emission shows evidence of
rotation of the parent core. Finally, we detected two new low mass compact
cores in this area (designated as SMM1 and SMM2), which may represent
prestellar objects.
