Discovery of Magellanic Stellar Debris in the H3 Survey
  We report the discovery of 15 stars in the H3 survey that lie, in projection,
near the tip of the trailing gaseous Magellanic Stream (MS). The stars have
Galactocentric velocities $< -155$ km s$^{-1}$, Galactocentric distances of
$\approx 40$ to 80 kpc (increasing along the MS), and [Fe/H] consistent with
that of stars in the Small Magellanic Cloud. These 15 stars comprise 94% (15 of
16) of the H3 observed stars to date that have $R_{GAL} > 37.5$ kpc, $-$350 km
s$^{-1} < V_{GSR} < -155$ km s$^{-1}$, and are not associated with the
Sagittarius Stream. They represent a unique portion of the Milky Way's outer
halo phase space distribution function and confirm that unrelaxed structure is
detectable even at radii where H3 includes only a few hundred stars. Due to
their statistical excess, their close association with the MS and H I compact
clouds in the same region, both in position and velocity space, and their
plausible correspondence with tidal debris in a published simulation, we
identify these stars as debris of past Magellanic Cloud encounters. These stars
are evidence for a stellar component of the tidal debris field far from the
Clouds themselves and provide unique constraints on the interaction.
