  It has been hypothesized that the presence of closely orbiting giant planets
is associated with enhanced chromospheric emission of their host stars. The
main cause for such a relation would likely be enhanced dynamo action induced
by the planet. We present measurements of chromospheric emission in 234 planet
candidate systems from the Kepler mission. This ensemble includes 37 systems
with giant planet candidates, which show a clear emission enhancement. The
enhancement, however, disappears when systems which are also identified as
eclipsing binary candidates are removed from the ensemble. This suggests that a
large fraction of the giant planet candidate systems with chromospheric
emission stronger than the Sun are not giant planet system, but false
positives. Such false-positive systems could be tidally interacting binaries
with strong chromospheric emission. This hypotesis is supported by an analysis
of 188 eclipsing binary candidates that show increasing chromospheric emission
as function of decreasing orbital period.
