Activity trends in young solar-type stars

June 14, 2016

In a multidecade study of the photometric variability of 21 young solar-type stars we found systematic tendencies in the behavior of the spot cycles and active longitudes of active stars. The lengths of the identified spot cycles follow a sequence of branches as a function of Rossby number or the stellar activity ...

In a multidecade study of the photometric variability of 21 young solar-type stars we found systematic tendencies in the behavior of the spot cycles and active longitudes of active stars. The lengths of the identified spot cycles follow a sequence of branches as a function of Rossby number or the stellar activity level. A split into parallel sub-branches within the diagram may point to the excitation of different cycle modes in the dynamos of different stars. We found that active longitudes, or persistent non-axisymmetric spot distribution, are common on the fast rotating and strongly active stars but absent on the slow rotating and moderately active ones. This is indicative of a transition between axisymmetric and non-axisymmetric dynamo modes between slow and fast rotating stars. In many cases we observed a significant difference between the active longitude rotation periods and the stellar bulk rotation, which may suggest the presence of longitudinally moving dynamo waves in these stars. more
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