Timescales of starspot variability in slow rotators

Abstract

There is an intriguing proximity between the turnover time τMLT of the standard mixing length theory of the Sun and the timescale τlam of solar activity patterns at the space scale of giant laminar convection assumed in deep layers of the Sun. To verify the reliability of this correspondence, we analyzed the light curves of 637 slowly rotating stars, observed by the Kepler mission, with periods from 16 to 30 days. The proximity τMLT ≈ τlam is confirmed. The performed study also confirms the manifestation of large scale turbulence in the dynamics of surface activity such as that in the Sun. These results open a new way to measure the key astrophysical parameter τMLT and to study deep convection that has been undetected with asteroseismology.