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arXiv · 1404.4359

Looking for activity cycles in late-type Kepler stars using time-frequency analysis

K. Vida·K. Oláh·R. Szabó
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Abstract

We analyse light curves covering four years of 39 fast-rotating ($P_\mathrm{rot}< 1d$) late-type active stars from the Kepler database. Using time-frequency analysis (Short-Term Fourier-Transform), we find hints for activity cycles of 300-900 days at 9 targets from the changing typical latitude of the starspots, which, with the differential rotation of the stellar surface change the observed rotation period over the activity cycle. We also give a lowest estimation for the shear parameter of the differential rotation, which is ~0.001 for the cycling targets. These results populate the less studied, short period end of the rotation-cycle length relation.

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K. Vida, K. Oláh, R. Szabó. 2014-04-16. Looking for activity cycles in late-type Kepler stars using time-frequency analysis. https://doi.org/10.1093/mnras%2Fstu760

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