The 3D Kinematics of Gas in the Small Magellanic Cloud
  We investigate the kinematics of neutral gas in the Small Magellanic Cloud
(SMC) and test the hypothesis that it is rotating in a disk. To trace the 3D
motions of the neutral gas distribution, we identify a sample of young, massive
stars embedded within it. These are stars with radial velocity measurements
from spectroscopic surveys and proper motion measurements from Gaia, whose
radial velocities match with dominant HI components. We compare the observed
radial and tangential velocities of these stars with predictions from the
state-of-the-art rotating disk model based on high-resolution 21 cm
observations of the SMC from the Australian Square Kilometer Array Pathfinder
telescope. We find that the observed kinematics of gas-tracing stars are
inconsistent with disk rotation. We conclude that the kinematics of gas in the
SMC are more complex than can be inferred from the integrated radial velocity
field. As a result of violent tidal interactions with the LMC, non-rotational
motions are prevalent throughout the SMC, and it is likely composed of distinct
sub-structures overlapping along the line of sight.
