An ALMA View of Dense Filamentary Fan-shaped Molecular Clouds in the Large Magellanic Cloud: Detailed Velocity Field Analysis and Comparison to an MHD Simulation

A supersonic collision of atomic and/or molecular clouds is a major mechanism of high-mass star formation. Such a collision is numerically simulated by magnetohydrodynamics to form the dense filamentary structures of molecular clouds(Inoue et al. 2018), and the observational test has been an issue of keen interest. We test this scheme of high-mass star formation in N159 in the molecular ridge region of the LMC because the 100 km/s atomic gas collision driven by the tidal interaction with the SMC has been reported (Fukui et al. 2017). Especially in N159E-Papillon and N159W-S, dense filamentary fan-shaped molecular clouds with lengths and opening angles of ~5 pc and ~30 deg, respectively, have masses of ~104 Mo (Fukui et al. 2019; Tokuda et al. 2019). However, the velocity fields of these regions have not been fully understood. We analyzed the ALMA Cycle 4 12CO and 13CO data in the N159E-Papillon, N159W-S, and N159W-N regions with a spatial resolution of 0.2 arcsec, particularly focusing on velocity fields of filamentary clouds. In the position-velocity cut perpendicular to the symmetric axis of the fan-shape in the three regions, the 12CO and 13CO gas indicate "cone-like" three dimensional distribution, which is in good agreement with Inoue et al. (2018).