Formation of the active star forming region LHA 120-N 44 triggered by
  tidally-driven colliding HI flows
  N44 is the second active site of high mass star formation next to R136 in the
Large Magellanic Cloud (LMC). We carried out a detailed analysis of HI at 60
arcsec resolution by using the ATCA & Parkes data. We presented decomposition
of the HI emission into two velocity components (the L- and D-components) with
the velocity separation of 60 km s$^{-1}$. In addition, we newly defined the
I-component whose velocity is intermediate between the L- and D-components. The
D-component was used to derive the rotation curve of the LMC disk, which is
consistent with the stellar rotation curve (Alves et al. 2000). Toward the
active cluster forming region of LHA 120-N 44, the three velocity components of
HI gas show signatures of dynamical interaction including bridges and
complementary spatial distributions. We hypothesize that the L- and
D-components have been colliding with each other since 5 Myrs ago and the
interaction triggered formation of the O and early B stars ionizing N44. In the
hypothesis the I-component is interpreted as decelerated gas in terms of
momentum exchange in the collisional interaction of the L- and D-components. In
the N44 region the Planck sub-mm dust optical depth is correlated with the HI
intensity, which is well approximated by a linear regression. We found that the
N44 region shows a significantly steeper regression line than in the Bar region
indicating less dust abundance in the N44 region, which is ascribed to the
tidal interaction between the LMC with the SMC 0.2 Gyrs ago.
