Tidal star-planet interaction revealed by its imact on stellar activity

The project we have been working on is concerned with the activity 
and evolution of exoplanet hosting stars. 
The hypothesis we were exploring is that close-in, more massive exoplanets 
may influence the rotation evolution of the host in particular, 
making the stellar host more active than expected for given age and SpT.
To avoid the dependence on age in estimating the expected activity level, 
we only investigated planet-hosting stars that have a stellar companion, 
which we used as a reference for the expected activity level 
(assuming ofc that they formed at approx the same time and from the same interstellar cloud).
As the activity indicator, we used the X-ray Luminosity 
which accounts for the activity of the stellar corona.
Although the sample does not allow for a definite conclusion
our results point us to a positive correlation between 
the activity level of the planet host and the strength of the SPI.