The Hercules satellite: a stellar stream in the Milky Way halo?
  We investigate the possibility that the recently discovered Hercules Milky
Way satellite is in fact a stellar stream in formation, thereby explaining its
very elongated shape with an axis ratio of 3 to 1. Under the assumption that
Hercules is a stellar stream and that its stars are flowing along the orbit of
its progenitor, we find an orbit that would have recently brought the system
close enough to the Milky Way to induce its disruption and transformation from
a bound dwarf galaxy into a stellar stream. The application of simple
analytical techniques to the tentative radial velocity gradient observed in the
satellite provides tight constraints on the tangential velocity of the system
(v_t = -16^{+6}_{-22} km/s in the Galactic Standard of Rest). Combined with its
large receding velocity, the determined tangential velocity yields an orbit
with a small pericentric distance (R_peri = 6^{+9}_{-2} kpc). Tidal disruption
is therefore a valid scenario for explaining the extreme shape of Hercules. The
increase in the mean flattening of dwarf galaxies as one considers fainter
systems could therefore be the impact of a few of these satellites not being
bound stellar systems dominated by dark matter but, in fact, stellar streams in
formation, shedding their stars in the Milky Way's stellar halo.
