The Magellanic Stream at 20 kpc: A New Orbital History for the
  Magellanic Clouds
  We present new simulations of the formation of the Magellanic Stream based on
an updated first-passage interaction history for the Magellanic Clouds,
including both the Galactic and Magellanic Coronae and a live dark matter halo
for the Milky Way. This new interaction history is needed because previously
successful orbits need updating to account for the Magellanic Corona and the
loosely bound nature of the Magellanic Group. These orbits involve two tidal
interactions over the last 3.5 Gyrs and reproduce the Stream's position and
appearance on the sky, mass distribution, and velocity profile. Most
importantly, our simulated Stream is only $\sim$20 kpc away from the Sun at its
closest point, whereas previous first-infall models predicted a distance of
$100-200$ kpc. This dramatic paradigm shift in the Stream's 3D position would
have several important implications. First, estimates of the observed neutral
and ionized masses would be reduced by a factor of $\sim$5. Second, the stellar
component of the Stream is also predicted to be $<$20 kpc away. Third, the
enhanced interactions with the MW's hot corona at this small distance would
substantially shorten the Stream's lifetime. Finally, the MW's UV radiation
field would be much stronger, potentially explaining the H$\alpha$ emission
observed along most of the Stream. Our prediction of a 20 kpc Stream could be
tested by searching for UV absorption lines towards distant MW halo stars
projected onto the Stream.
