  Young, OB-type candidates are identified in a ~7900 sq-deg. region
encompassing the Large and Small Magellanic Clouds (LMC/SMC) periphery, the
Bridge, part of the Magellanic Stream (MS) and Leading Arm (LA). Selection is
based on UV, optical and IR photometry from existing large-area surveys and
proper motions from the Southern Proper Motion 4 catalog (SPM4). The spatial
distribution of these young star candidates shows: 1) a well-populated SMC wing
which continues westward with two branches partially surrounding the SMC, 2) a
rather narrow path from the SMC wing eastward toward the LMC which is offset by
1 to 2 deg. from the high-density H I ridge in the Bridge, 3) a well-populated
periphery of the LMC dominated by clumps of stars at the ends of the LMC bar
and 4) a few scattered candidates in the MS and two overdensities in the LA
regions above and below the Galactic plane. Additionally, a proper-motion
analysis is made of a radial-velocity selected sample of red giants and
supergiants in the LMC, previously shown to be a kinematically and chemically
distinct subgroup, most likely captured from the SMC. SPM4 proper motions of
these stars also indicate they are distinct from the LMC population. The
observational results presented here, combined with the known orbits of the
Clouds, and other aspects of the LMC morphology, suggest an off-center,
moderate to highly-inclined collision between the SMC and the LMC's disk that
took place between 100 and 200 Myr ago.

Astrophysics of Galaxies