  Although warm jupiters are generally too far from their stars for tides to be
important, the presence of an inner planetary companion to a warm jupiter can
result in tidal evolution of the system. Insight into the process and its
effects comes form classical secular theory of planetary perturbations. The
lifetime of the inner planet may be shorter than the age of the system, because
the warm jupiter maintains its eccentricity and hence promotes tidal migration
into the star. Thus a warm jupiter observed to be alone in its system might
have previously cleared away any interior planets. Before its demise, even if
an inner planet is of terrestrial scale, it may promote damping of the warm
jupiter's eccentricity. Thus any inferences of the initial orbit of an observed
warm jupiter must include the possibility of a greater initial eccentricity
than would be estimated by assuming it had always been alone. Tidal evolution
involving multiple planets also enhances the internal heating of the planets,
which readily exceeds that of stellar radiation for the inner planet, and may
be great enough to affect the internal structure of warm jupiters. Secular
theory gives insight into the tidal processes, providing, among other things, a
way to constrain eccentricities of transiting planets based on estimates of the
tidal parameter Q.
