Evolution of solar and stellar dynamo theory

Abstract

In this paper, written as a general historical and technical introduction to the various review papers collected in the special issue ``Solar and Stellar Dynamo: A New Era'', we review the evolution and current state of dynamo theory and modelling, with emphasis on the solar dynamo. Starting with a historical survey, we then focus on a set of ``tension points'' that are still left unresolved despite the remarkable progress of the past century. In our discussion of these tension points we touch upon the physical well-posedness of mean-field electrodynamics; constraints imposed by magnetic helicity conservation; the troublesome role of differential rotation; meridional flows and flux transpost dynamos; competing inductive mechanisms and Babcock-Leighton dynamos; the ambiguous precursor properties of the solar dipole; cycle amplitude regulation and fluctuation through nonlinear backreaction and stochastic forcing, including Grand Minima; and the promises and puzzles offered by global magnethydrodynamical numerical simulations of convection and dynamo action. We close by considering the potential bridges to be constructed between solar dynamo theory and modelling, and observations of magnetic activity in late-type stars.

arXiv comment37 pages, 5 figures, in collection "Solar and Stellar Dynamos: A New Era"(ISSI, June 2022) ; submitted to Space Science Reviews

References in corpus (88)

• Astrophysical magnetic fields and nonlinear dynamo theory
• The Solar Cycle
• The inverse cascade and nonlinear alpha-effect in simulations of isotropic helical hydromagnetic turbulence
• Global-Scale Turbulent Convection and Magnetic Dynamo Action in the Solar Envelope
• Predicting solar cycle 24 with a solar dynamo model
• Detection of Equatorward Meridional Flow and Evidence of Double-Cell Meridional Circulation inside the Sun
• The stellar rotation--activity relationship in fully convective M dwarfs
• Solar cycle prediction
• Mean-field concept and direct numerical simulations of rotating magnetoconvection and the geodynamo
• Solar activity forecast with a dynamo model
• Flux-transport dynamos with Lorentz force feedback on differential rotation and meridional flow: Saturation mechanism and torsional oscillations
• The Maunder minimum (1645--1715) was indeed a Grand minimum: A reassessment of multiple datasets
• From solar-like to anti-solar differential rotation in cool stars
• Prediction of the strength and timing of sunspot cycle 25 reveal decadal-scale space environmental conditions
• The crucial role of surface magnetic fields for the solar dynamo
• Dynamic nonlinearity in large scale dynamos with shear
• Magnetism, rotation, and nonthermal emission in cool stars -- Average magnetic field measurements in 292 M dwarfs
• Predicting the Sun's Polar Magnetic Fields with a Surface Flux Transport Model
• Magnetic Wreaths and Cycles in Convective Dynamos
• Meridional Circulation in Solar and Stellar Convection Zones
• Magnetic Flux Transport at the Solar Surface
• A simulation of convective dynamo in the solar convective envelope: maintenance of the solar-like differential rotation and emerging flux
• Solar Meridional Circulation from Doppler Shifts of the Fe I line at lambda 5250 Angstroms as Measured by the 150-foot Solar Tower Telescope at the Mt. Wilson Observatory
• Solar activity during the Holocene: the Hallstatt cycle and its consequence for grand minima and maxim
• Grand Minima and Equatorward Propagation in a Cycling Stellar Convective Dynamo
• On the role of meridional flows in flux transport dynamo models
• The Rise of Active Region Flux Tubes in the Turbulent Solar Convective Envelope
• Towards A Mean-Field Formulation Of The Babcock-Leighton Type Solar Dynamo. I. Alpha Coefficient Versus Durney's Double Ring Approach
• Global helioseismic evidence for a deeply penetrating Solar meridional flow consisting of multiple flow cells
• Is a deep one-cell meridional circulation essential for the flux transport Solar Dynamo?
• Meridional circulation in the solar convection zone: time-distance helioseismic inferences from four years of HMI/SDO observations
• Local and nonlocal magnetic diffusion and alpha-effect tensors in shear flow turbulence
• Magnetoconvection and dynamo coefficients: II. Field-direction dependent pumping of magnetic field
• A Solar Dynamo Model Driven by Mean-Field Alpha and Babcock-Leighton Sources: Fluctuations, Grand-Minima-Maxima and Hemispheric Asymmetry in Sunspot Cycles
• The origin of grand minima in the sunspot cycle
• Magnetically controlled stellar differential rotation near the transition from solar to anti-solar profiles
• Differential rotation of main-sequence dwarfs and its dynamo-efficiency
• Multiple dynamo modes as a mechanism for long-term solar activity variations
• Solar activity over nine millennia: A consistent multi-proxy reconstruction
• Turbulent magnetic pumping in a Babcock-Leighton solar dynamo model
• Solar Grand Minima and random fluctuations in dynamo parameters
• Magnetic Twist and Writhe of Active Regions: On the Origin of Deformed Flux Tubes
• New dynamo pattern revealed by solar helical magnetic fields
• Recovering Joys Law as a Function of Solar Cycle, Hemisphere, and Longitude
• Powering Stellar Magnetism: Energy Transfers in Cyclic Dynamos of Sun-like Stars
• Modeling Solar Cycles 15 to 21 Using a Flux Transport Dynamo
• Small-scale magnetic helicity losses from a mean-field dynamo
• Meridional Flow in the Solar Convection Zone II: Helioseismic Inversions of GONG Data
• Comparing Simulations of Rising Flux Tubes Through the Solar Convection Zone with Observations of Solar Active Regions: Constraining the Dynamo Field Strength
• Grand Minima and North-South Asymmetry of Solar Activity
• Large scale dynamos with helicity loss through boundaries
• Dynamo-driven plasmoid ejections above a spherical surface
• Solar differential rotation reproduced with high-resolution simulation
• On the sensitivity of magnetic cycles in global simulations of solar-like stars
• A Stochastically Forced Time Delay Solar Dynamo Model: Self-Consistent Recovery from a Maunder-like Grand Minimum Necessitates a Mean-Field Alpha Effect
• Turbulent transport coefficients in spherical wedge dynamo simulations of solar-like stars
• Generation solar-like differential rotation
• Understanding solar cycle variability
• Variations of the solar cycle profile in a solar dynamo with fluctuating dynamo governing parameters
• The Origin of Weakened Magnetic Braking in Old Solar Analogs
• Dynamo cycles in global convection simulations of solar-like stars
• Global model of differential rotation in the Sun
• Convection-driven spherical shell dynamos at varying Prandtl numbers
• A coupled 2$\times$2D Babcock-Leighton solar dynamo model. I. Surface magnetic flux evolution
• Changes of the solar meridional velocity profile during cycle 23 explained by flows towards the activity belts
• Effects of Penetrative Convection on Solar Dynamo
• Towards an algebraic method of solar cycle prediction I. Calculating the ultimate dipole contributions of individual active regions
• What sets the magnetic field strength and cycle period in solar-type stars?
• Characterisation of the turbulent electromotive force and its magnetically-mediated quenching in a global EULAG-MHD simulation of solar convection
• Common dynamo scaling in slowly rotating young and evolved stars
• The Origin of Parity Changes in the Solar Cycle
• Modelling turbulent stellar convection zones: sub-grid scales effects
• Parameter optimization for surface flux transport models
• A proposed paradigm for solar cycle dynamics mediated via turbulent pumping of magnetic flux in Babcock-Leighton type solar dynamos
• The mean-field solar dynamo with double cell meridional circulation pattern
• How supercritical are stellar dynamos, or why do old main-sequence dwarfs not obey gyrochronology?
• Mean-field solar dynamo models with strong meridional flow at the bottom of the convection zone
• Differential Rotation in Magnetized and Non-magnetized Stars
• Transport of toroidal magnetic field by the meridional flow at the base of the solar convection zone
• Dynamo Effects Near The Transition from Solar to Anti-Solar Differential Rotation
• Role of observable nonlinearities in solar cycle modulation
• Stellar mid-life crisis: subcritical magnetic dynamos of solar-like stars and the breakdown of gyrochronology
• Stellar dynamos in the transition regime: multiple dynamo modes and anti-solar differential rotation
• Towards understanding dynamo action in M dwarfs
• Nature of grand minima and maxima from fully non-linear Flux-Transport Dynamos
• Toroidal flux loss due to flux emergence explains why solar cycles rise differently but decay in a similar way
• Evidence of persistence of weak magnetic cycles driven by meridional plasma flows during solar grand minima phases
• Mean-field analysis on large-scale magnetic fields at high Reynolds numbers

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• Transition to chaos and magnetic field generation in rotating Rayleigh-Bénard convection
• On the Geometry of the Near-Core Magnetic Field in Massive Stars
• Breaking gyrochronology through the collapse of coronal winds
• Solar poloidal magnetic field generation rate from observations and mean-field dynamos
• Solar Cycle Prediction: Challenges, Progress, and Future Perspectives
• Vortex-magnetic competition and regime transitions in antiparallel flux tubes
• Magnetic activity and differential rotation of HIP12653