Stellar Activity Cycles in a Model for Magnetic Flux Generation and Transport

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Işık, Emre
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Cambridge Univ Press, The Pitt Building, Trumpington St, Cambridge Cb2 1Rp, Cambs, England
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We present results from a model for magnetic flux generation and transport in cool stars and a qualitative comparison of models with observations. The method combines an alpha Omega-type dynamo at the base of the convection zone, buoyant rise of magnetic flux tubes, and a surface flux transport model. Based on a reference model for the Sun, numerical simulations were carried out for model convection zones of G- and K-type main sequence and subgiant stars. We investigate magnetic cycle properties for stars with different rotation periods, convection zone depths, and dynamo strengths. For a Sun-like star with P-rot=9 d, we find that a cyclic dynamo can underly an apparently non-cyclic, 'flat' surface activity, as observed in some stars. For a subgiant K1 star with P-rot=2.8 d the long-term activity variations resemble the multi-periodic cycles observed in V711 Tau, owing to high-latitude flux emergence, weak transport effects and stochastic processes of flux emergence.
Stars, Activity, Stars: Interiors, Stars: Magnetic Fields, (magnetohydrodynamics:) MUD, Sun: Interior, Sun: Magnetic Fields, Yıldızlar, Aktivite, Yıldızlar: İç Mekanlar, Yıldızlar: Manyetik Alanlar, Güneş: İç, Güneş: Manyetik Alanlar