  The Kepler mission has collected light curves for almost 4 years. The
excellent quality of these data has allowed us to probe the structure and the
dynamics of the stars using asteroseismology. With the length of data
available, we can start to look for magnetic activity cycles. The Kepler data
obtained for the F star, KIC 12009504, shows a rotation period of 9.5 days and
additional variability that could be due to the magnetic activity of the star.
Here we present recent and preliminary 3D global-scale dynamo simulations of
this star with the ASH and STELEM codes, capturing a substantial portion of the
convection and the stable radiation zone below it. These simulations reveal a
multi-year activity cycle whose length tentatively depends upon the width of
the tachocline present in the simulation. Furthermore, the presence of a
magnetic field and the dynamo action taking place in the convection zone
appears to help confine the tachocline, but longer simulations will be required
to confirm this.

Solar and Stellar Astrophysics