Description
We present an extensive study on the dynamo origin of solar-type star's magnetism, based on a series of 32 3D MHD global numerical simulations of rotating magnetised convection. We quantify how the combination of rotation and convection via the Rossby number influences the type of magnetism established (short or long cycles, statistically steady activity) and their expected differential rotation (solar-like, anti-solar, cylindrical or almost solid). This large survey allows us to propose a possible solution to why the Sun possesses a long decadal cycle and a conical differential rotation. The solar conical differential rotation and decadal cycle are recovered in a specific range of Rossby numbers, which opens up the possibility to use this dimensional parameter to define a path in parameter space towards more and more turbulent models while retaining key force balances thought to operate in the Sun. We further assess the amount of energy needed to maintain such angular velocity profiles and magnetic activity. We find that between 0.1 and 3% of the stellar luminosity can be converted into magnetic energy, giving plenty of energy for surface eruptive events to occur. We also compute the magnetic energy spectra and show how the dipole and quadrupole magnetic fields evolve as the Sun ages and compare the trend found with observations finding a good overall agreement. In particular interesting regimes at low and high Rossby number are identified.
