  We present a novel and flexible tensor approach to computing the effect of a
time-dependent tidal field acting on a stellar system. The tidal forces are
recovered from the tensor by polynomial interpolation in time. The method has
been implemented in a direct-summation stellar dynamics integrator (NBODY6) and
test-proved through a set of reference calculations: heating, dissolution time
and structural evolution of model star clusters are all recovered accurately.
The tensor method is applicable to arbitrary configurations, including the
important situation where the background potential is a strong function of
time. This opens up new perspectives in stellar population studies reaching to
the formation epoch of the host galaxy or galaxy cluster, as well as for
star-burst events taking place during the merger of large galaxies. A pilot
application to a star cluster in the merging galaxies NGC 4038/39 (the
Antennae) is presented.
