An ALMA view of molecular filaments in the Large Magellanic Cloud I: The
  formation of high-mass stars and pillars in the N159E-Papillon Nebula
  triggered by a cloud-cloud collision
  We present the ALMA observations of CO isotopes and 1.3 mm continuum emission
toward the N159E-Papillon Nebula in the Large Magellanic Cloud (LMC). The
spatial resolution is 0"25-0"28 (0.06-0.07 pc), which is a factor of 3 higher
than the previous ALMA observations in this region. The high resolution allowed
us to resolve highly filamentary CO distributions with typical widths of
$\sim$0.1 pc (full width half maximum) and line masses of a few 100 $M_{\odot}$
pc$^{-1}$. The filaments (more than ten in number) show an outstanding
hub-filament structure emanating from the nebular center toward the north. We
identified for the first time two massive protostellar outflows of $\sim$10$^4$
yr dynamical age along one of the most massive filaments. The observations also
revealed several pillar-like CO features around the Nebula. The H II region and
the pillars have a complementary spatial distribution and the column density of
the pillars is an order of magnitude higher than that of the pillars in the
Eagle nebula (M16) in the Galaxy, suggesting an early stage of pillar formation
with an age younger than $\sim$10$^5$ yr. We suggest that a cloud-cloud
collision triggered the formation of the filaments and protostar within the
last $\sim$2 Myr. It is possible that the collision is more recent, as part of
the kpc-scale H I flows come from the tidal interaction resulting from the
close encounter between the LMC and SMC $\sim$200 Myr ago as suggested for R136
by Fukui et al.
