Traveling Waves of Magnetoconvection and the Origin of the Evershed Effect in Sunspots

Abstract

Discovered in 1909 the Evershed effect represents strong mass outflows in sunspot penumbra, where the magnetic field of sunspots is filamentary and almost horizontal. These flows play important role in sunspots and have been studied in detail using large ground-based and space telescopes, but the basic understanding of its mechanism is still missing. We present results of realistic numerical simulations of the Sun's subsurface dynamics, and argue that the key mechanism of this effect is in non-linear magnetoconvection that has properties of traveling waves in the presence of strong, highly inclined magnetic field. The simulations reproduce many observed features of the Evershed effect, including the high-speed "Evershed clouds", the filamentary structure of the flows, and the non-stationary quasi-periodic behavior. The results provide a synergy of previous theoretical models and lead to an interesting prediction of a large-scale organization of the outflows.

12 pages, 5 figures; submitted to ApJ Letters

References in corpus (6)

• MHD simulations of penumbra fine structure
• Convection and the origin of Evershed flows in sunspot penumbrae
• Temporal evolution of the Evershed flow in sunspots. I. Observational characterization of Evershed clouds
• Numerical simulation of excitation of solar oscillation modes for different turbulent models
• Temporal evolution of the Evershed flow in sunspots. II. Physical properties and nature of Evershed clouds
• Structure and Dynamics of Sunspots

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• Challenges and Advances in Modeling of the Solar Atmosphere: A White Paper of Findings and Recommendations
• Diverging and Converging Flows around Sunspot Structures in Rotating and Non-Rotating Axisymmetric MHD Simulations
• LES of turbulent convection in solar-type stars and formation of large-scale magnetic structures