An ALMA view of molecular filaments in the Large Magellanic Cloud II: An
  early stage of high-mass star formation embedded at colliding clouds in
  N159W-South
  We have conducted ALMA CO isotopes and 1.3 mm continuum observations toward
filamentary molecular clouds of the N159W-South region in the Large Magellanic
Cloud with an angular resolution of $\sim$0"25 ($\sim$0.07 pc). Although the
previous lower-resolution ($\sim$1") ALMA observations revealed that there is a
high-mass protostellar object at an intersection of two line-shaped filaments
in $^{13}$CO with the length scale of $\sim$10 pc, the spatially resolved
observations, in particular, toward the highest column density part traced by
the 1.3 mm continuum emission, the N159W-South clump, show complicated
hub-filamentary structures. We also discovered that there are multiple
protostellar sources with bipolar outflows along the massive filament. The
redshifted/blueshifted components of the $^{13}$CO emission around the massive
filaments/protostars have complementary distributions, which is considered to
be a possible piece of evidence for a cloud-cloud collision. We propose a new
scenario in which the supersonically colliding gas flow triggers the formation
of both the massive filament and protostars. This is a modification of the
earlier scenario of cloud-cloud collision, by Fukui et al., that postulated the
two filamentary clouds occur prior to the high-mass star formation. A recent
theoretical study of the shock compression in colliding molecular flows by
Inoue et al. demonstrates that the formation of filaments with hub structure is
a usual outcome of the collision, lending support for the present scenario. The
theory argues that the filaments are formed as dense parts in a shock
compressed sheet-like layer, which resembles $"$an umbrella with pokes.$"$
