  We combine GALEX and Gaia DR2 catalogs to track star formation in the
outskirts of our Galaxy. Using photometry, proper motions and parallaxes we
identify a structure of ~ 300 OB-type candidates located between 12 and 15 kpc
from the Galactic center that are kinematically cold. The structure is located
between l = 120 and 200 degrees, above the plane up to ~700 pc and below the
plane to ~ 1 kpc. The bulk motion is disk-like; however we measure a mean
upward vertical motion of 5.7 +-0.4 km/s, and a mean outward radial motion of
between 8 and 16 km/s. The velocity dispersion along the least dispersed of its
proper-motion axes (perpendicular to the Galactic disk) is 6.0 +-0.3 km/s
confirming the young age of this structure.
  While spatially encompassing the outer spiral arm of the Galaxy, this
structure is not a spiral arm. Its explanation as the Milky-Way warp is equally
unsatisfactory. The structure's vertical extent, mean kinematics and asymmetry
with respect to the plane indicate that its origin is more akin to a wobble
generated by a massive satellite perturbing the Galaxy's disk. The mean stellar
ages in this outer structure indicate the event took place some 200 Myr ago.
