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Full-Text Articles in Physical Sciences and Mathematics
Butterfly Diagram And Activity Cycles In Hr 1099, Svetlana Berdyugina, Gregory W. Henry
Butterfly Diagram And Activity Cycles In Hr 1099, Svetlana Berdyugina, Gregory W. Henry
Information Systems and Engineering Management Research Publications
We analyze photometric data of the active RS CVn-type star HR 1099 for the years 1975-2006 with an inversion technique and reveal the nature of two activity cycles of 15-16 yr and 5.3 ± 0.1 yr duration. The 16 yr cycle is related to variations of the total spot area and is coupled with the differential rotation, while the 5.3 yr cycle is caused by the symmetric redistribution of the spotted area between the opposite stellar hemispheres (flip-flop cycle). We recover long-lived active regions comprising two active longitudes that migrate in the orbital reference frame with a variable rate because …
Photospheric And Chromospheric Active Regions In Four Young Solar-Type Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, E. Marilli
Photospheric And Chromospheric Active Regions In Four Young Solar-Type Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, E. Marilli
Information Systems and Engineering Management Research Publications
We present a photometric and spectroscopic study of four G-K dwarfs, namely HD 166, epsilon Eri, χ1 Ori, and κ1 Cet. In three cases, we find a clear spatial association between photospheric and chromospheric active regions. For χ1 Ori we do not find appreciable variations of photospheric temperature or chromospheric Hα emission. We applied a spot/plage model to the observed rotational modulation of temperature and flux to derive spot/plage parameters and to reconstruct a rough "three-dimensional" map of the outer atmosphere of κ1 Cet, HD 166, and epsilon Eri.