Dynamo modeling of the Kepler F star KIC 12009504

TL;DR

This paper presents 3D dynamo simulations of the Kepler F star KIC 12009504, revealing a multi-year magnetic activity cycle and insights into the star's internal magnetic dynamics and structure.

Contribution

The study introduces the first 3D global-scale dynamo simulations of KIC 12009504, linking magnetic activity cycles to tachocline properties.

Findings

Revealed a multi-year activity cycle in simulations.

Showed magnetic fields help confine the tachocline.

Cycle length depends on tachocline width.

Abstract

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.