About this Research Topic
Solar/stellar magnetic activity has an important impact on the evolution of planets/exoplanets. High energy radiation and particles after flares and coronal mass ejections cause complex effects in the planetary atmospheres. The Sun's magnetic activity has a 11-yr periodicity (Schwabe cycle) rooted in the internal dynamo layer, where the powerful magnetic field is generated. The magnetic flux then rises towards the surface via magnetic buoyancy leading to high energy release in the atmosphere. Besides the Schwabe cycles, solar activity displays shorter periodicity on time scales of several months (150-180 days, Rieger-type periodicity) and few years (annual and quasi-biennial oscillations), which are observed in many activity indices. These periodicities can be related with the internal dynamo layer and hence may provide the layer diagnostics with the help of corresponding theoretical background.
Recent space missions CoRoT (Convection, Rotation and planetary Transits), Kepler and TESS (Transiting Exoplanet Survey Satellite) collected huge information about activity of hundreds of thousands stars. Starspots and other magnetic structures (faculae, prominence) modulate stellar light curves and provide important information about magnetic activity. Observations show short term cycles in stellar light curves, though more detailed analysis of stars at different evolutionary stages is needed.
Using solar and stellar analogy, short term stellar cycles can be used as diagnostics of stellar atmospheric/internal layers and hence help us to follow the evolution of stellar dynamo along main sequence. They can also mimic radial-velocity signals similar to those produced by planets in the habitable zone of Sun-like stars, thus their characterization can be relevant also for the discovery of such planets.
The scope of the Research Topic is to collect research papers about short term cycles in solar and stellar activity, their relation with ordinary (Schwabe) cycles, theoretical background for their occurrence and solar-stellar dynamos. Any other subject related with activity cycles and solar-stellar dynamos is also welcome.
Keywords: Solar/Stellar activity, Short term cycles, Magnetic dynamo, Stellar-planetary interaction, Exoplanets
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