  When a star gets too close to a supermassive black hole, it is torn apart by
the tidal forces. Roughly half of the stellar mass becomes unbound and flies
away at tremendous velocities - around $10^4$ km/s. In this work we explore the
idea that the shock produced by the interaction of the unbound debris with the
ambient medium gives rise to the synchrotron radio emission observed in several
TDEs. We use a moving mesh numerical simulation to study the evolution of the
unbound debris and the bow shock around it. We find that as the periapse
distance of the star decreases, the outflow becomes faster and wider. A tidal
disruption event whose periapse distance is a factor of 7 smaller than the
tidal radius can account for the radio emission observed in ASASSN-14li. This
model also allows us to obtain a more accurate estimate for the gas density
around the centre of the host galaxy of ASASSN-14li.
