Gaia view of a stellar sub-structure in front of the Small Magellanic
  Cloud
  Recent observational studies identified a foreground stellar sub-structure
traced by red clump (RC) stars (~ 12 kpc in front of the main body) in the
eastern regions of the Small Magellanic Cloud (SMC) and suggested that it
formed during the formation of the Magellanic Bridge (MB), due to the tidal
interaction of the Magellanic Clouds. Previous studies investigated this
feature only up to 4.0 deg from the centre of the SMC due to the limited
spatial coverage of the data and hence could not find a physical connection
with the MB. To determine the spatial extent and properties of this foreground
population, we analysed data from the Gaia data release 2 (DR2) of a ~ 314 sq.
deg region centred on the SMC, which cover the entire SMC and a significant
portion of the MB. We find that the foreground population is present only
between 2.5 deg to ~ 5-6 deg from the centre of the SMC in the eastern regions,
towards the MB and hence does not fully overlap with the MB in the plane of the
sky. The foreground stellar population is found to be kinematically distinct
from the stellar population of the main body with ~ 35 km/s slower tangential
velocity and moving to the North-West relative to the main body. Though the
observed properties are not fully consistent with the simulations, a comparison
indicates that the foreground stellar structure is most likely a tidally
stripped counterpart of the gaseous MB and might have formed from the inner
disc (dominated by stars) of the SMC. A chemical and 3D kinematic study of the
RC stars along with improved simulations, including both tidal and
hydro-dynamical effects, are required to understand the offset between the
foreground structure and MB.
