Tachocline Alfvén waves manifested in stellar activity

Context. The short-time (< 700 days) periodicities of both the stellar and solar activity that controls space weather are usually discussed as manifestations Rossby modes in tachoclines. Various interpretations this phenomenon have been proposed, particular for Sun, can be verified by considering broad population nonsolar-type stars. Aims. We look surface features, drifting longitude, compare their drift rates with those predicted different low-frequency waves photospheres Methods. Analogously to Hovmöller diagrams meteorology, we constructed a dynamic diagram pattern (DDSAP) visualize rotational variability radiation flux function rotation phase time. used high-precision light curves fast-rotating main sequence stars, periods 0.5 4 days, from Kepler mission database. Results. found quasi-periodic lanes (DLs) various durations intensities DDSAPs 108 In course analysis, carried out correction nullifying drifts longest-lasing DLs presumably related long-lived starspot complexes co-rotating star. discovered clear elongated cluster absolute values DLs’ versus effective temperatures. This cannot attributed any accidental contaminations or manifestation photospheres, because extremely short timescales. An approximate equality positive negative considered makes it impossible interpret them terms Kelvin and/or magneto-Rossby It is only global kink-type Alfvénic oscillations tachocline whole allow us estimated forming above-mentioned cluster, well turnover times convective zones. corresponding magnetic field strength appears about 50 kG, which approximately middle range assumptions literature. Conclusions. Alfvén an important, albeit commonly ignored factor interiors. Apparently, tachocline’s ought play role triggering emergence tubes. Their opens up unique way probing tachoclines individual Since investigations performed thus far based on shallow-fluid approximation, also assuming rigid fixed bottom layer, Alvénic disturbances layer not considered. reported observational detection signatures such waves, manifested specific longitude stelar pattern, calls more detailed theoretical study.