  Stellar shells observed in many giant elliptical and lenticular as well as a
few spiral and dwarf galaxies presumably result from radial minor mergers of
galaxies. We show that the line-of-sight velocity distribution of the shells
has a quadruple-peaked shape. We found simple analytical expressions that
connect the positions of the four peaks of the line profile with the mass
distribution of the galaxy, namely, the circular velocity at the given shell
radius and the propagation velocity of the shell. The analytical expressions
were applied to a test-particle simulation of a radial minor merger, and the
potential of the simulated host galaxy was successfully recovered. Shell
kinematics can thus become an independent tool to determine the content and
distribution of dark matter in shell galaxies up to ~100 kpc from the center of
the host galaxy. Moreover we investigate the dynamical friction and gradual
disruption of the cannibalized galaxy during the shell formation in the
framework of a simulation with test particles. The coupling of both effects can
considerably redistribute positions and luminosities of shells. Neglecting them
can lead to significant errors in attempts to date the merger in observed shell
galaxies.
