On the tidal radius of satellites on prograde and retrograde orbits
  A tidal radius is a distance from a satellite orbiting in a host potential
beyond which its material is stripped by the tidal force. We derive a revised
expression for the tidal radius of a rotating satellite which properly takes
into account the possibility of prograde and retrograde orbits of stars.
Besides the eccentricity of the satellite orbit, the tidal radius depends also
on the ratio of the satellite internal angular velocity to the orbital angular
velocity. We compare our formula to the results of two $N$-body simulations of
dwarf galaxies orbiting a Milky Way-like host on a prograde and retrograde
orbit. The tidal radius for the retrograde case is larger than for the
prograde. We introduce a kinematic radius separating stars still orbiting the
dwarf galaxy from those already stripped and following the potential of the
host galaxy. We find that the tidal radius matches very well the kinematic
radius. Our results provide a connection between the formalism of the tidal
radius derivation and the theory of resonant stripping.
