Time-scales of stellar rotational variability and starspot diagnostics

Oleksiy V Arkhypov, Maxim L Khodachenko, Helmut Lammer, Manuel Güdel, Teresa Lüftinger, Colin P Johnstone
2017 Monthly Notices of the Royal Astronomical Society: Letters  
The difference in stability of starspot distribution on the global and hemispherical scales is studied in the rotational spot variability of 1998 main-sequence stars observed by Kepler mission. It is found that the largest patterns are much more stable than smaller ones for cool, slow rotators, whereas the difference is less pronounced for hotter stars and/or faster rotators. This distinction is interpreted in terms of two mechanisms: (1) the diffusive decay of longliving spots in activity
more » ... exes of stars with saturated magnetic dynamos, and (2) the spot emergence, which is modulated by gigantic turbulent flows in convection zones of stars with a weaker magnetism. This opens a way for investigation of stellar deep convection, which is yet inaccessible for asteroseismology. Moreover, a subdiffusion in stellar photospheres was revealed from observations for the first time. A diagnostic diagram was proposed that allows differentiation and selection of stars for more detailed studies of these phenomena.
doi:10.1093/mnrasl/slx170 fatcat:tcye43ncivgrhlmrgly665rdfq