  We present the results of hydrodynamic simulations of the interaction between
a 10 Jupiter mass planet and a red or asymptotic giant branch stars, both with
a zero-age main sequence mass of 3.5 $M_\odot$. Dynamic in-spiral timescales
are of the order of few years and a few decades for the red and asymptotic
giant branch stars, respectively. The planets will eventually be destroyed at a
separation from the core of the giants smaller than the resolution of our
simulations, either through evaporation or tidal disruption. As the planets
in-spiral, the giant stars' envelopes are somewhat puffed up. Based on
relatively long timescales and even considering the fact that further in-spiral
should take place before the planets are destroyed, we predict that the merger
would be difficult to observe, with only a relatively small, slow brightening.
Very little mass is unbound in the process. These conclusions may change if the
planet's orbit enhances the star's main pulsation modes. Based on the angular
momentum transfer, we also suspect that this star-planet interaction may be
unable to lead to large scale outflows via the rotation-mediated dynamo effect
of Nordhaus and Blackman. Detectable pollution from the destroyed planets would
only result for the lightest, lowest metallicity stars. We furthermore find
that in both simulations the planets move through the outer stellar envelopes
at Mach-3 to Mach-5, reaching Mach-1 towards the end of the simulations. The
gravitational drag force decreases and the in-spiral slows down at the sonic
transition, as predicted analytically.
