Role of helicity in Solar and Stellar Dynamos
Max Planck Institute for Solar System Science
Main category
Natural Sciences (Astrophysics and Astrononmy)
The magnetic field in the Sun undergoes a cyclic modulation with a reversal typically every 11 years due to a dynamo operating under the surface. We simulate slowly to rapidly rotating solar-type stars, where the interplay between convection and rotation self-consistently drives large-scale magnetic field. We apply the test-field method to characterise the dynamo mechanisms acting in this simulations by determining turbulent transport coefficients of the electromotive force. We find that the alphaeffect has a complex nature and does not follow the profile expected from kinetic helicity. However, the alpha effects in these simulations show strong rotational dependency resulting in highly anisotropic tensors and vanish alpha_zz components for rapid rotation. Furthermore, I will present the determination of magnetic helicity fluxes across the equator and through the surface, which are important quantities for the alleviation of catastrophically alpha quenching. Unlike in simulation of forced turbulence of Warnecke et al. (2011), the helicity fluxes across the equator are found to be much weaker in convection simulations. Moreover, I discuss the the relevants of magnetic and current helicity production in the dynamo region for the coronal heating process as well as to understand the activity-rotation-relation of main-sequence stars.
Further information
Further reading
Do you have problems viewing the pdf-file? Download presentation here
If the presentation contains inappropriate content, please report the presentation. You will be redirected to the landing page.