Models and Observations of Sunspot Penumbrae

Abstract

The mysteries of sunspot penumbrae have been under an intense scrutiny for the past 10 years. During this time, some models have been proposed and refuted, while the surviving ones had to be modified, adapted and evolved to explain the ever-increasing array of observational constraints. In this contribution I will review two of the present models, emphasizing their contributions to this field, but also pinpointing some of their inadequacies to explain a number of recent observations at very high spatial resolution. To help explaining these new observations I propose some modifications to each of them. These modifications bring those two seemingly opposite models closer together into a general picture that agrees well with recent 3D magneto-hydrodynamic simulations.

9 pages, 1 color figure. Review talk to appear in the proceedings of the International Workshop of 2008 Solar Total Eclipse: Solar Magnetism, Corona and Space Weather--Chinese Space Solar Telescope Science

References in corpus (23)

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• Magneto-convection in a sunspot umbra
• Fine structure, magnetic field and heating of sunspot penumbrae
• MHD simulations of penumbra fine structure
• Magnetostatic penumbra models with field-free gaps
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• Are there field-free gaps near tau=1 in sunspot penumbrae?
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• Flux tubes as the origin of Net Circular Polarization in Sunspot Penumbrae
• The Fine-Structure of the Net-Circular Polarization in a Sunspot Penumbra
• The velocity structure of moving magnetic feature pairs around sunspots: support for the U-loop model
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Cited by in corpus (12)

• Numerical sunspot models: Robustness of photospheric velocity and magnetic field structure
• Penumbral fine structure and driving mechanisms of large-scale flows in simulated sunspots
• Structure of sunspot penumbral filaments: a remarkable uniformity of properties
• Returning magnetic flux in sunspot penumbrae
• A geometrical height scale for sunspot penumbrae
• Normal and counter Evershed flows in the photospheric penumbra of a sunspot. SPINOR 2D inversions of Hinode-SOT/ SP observations
• Solar ALMA observations: constraining the chromosphere above sunspots
• Evershed and counter-Evershed flows in sunspot MHD simulations
• Searching for overturning convection in penumbral filaments: slit spectroscopy at 0.2 arcsec resolution
• Twist, Writhe & Helicity in the inner penumbra of a sunspot
• The formation of a penumbra as observed with the German VTT and SoHO/MDI
• What determines the penumbral size and Evershed flow speed?