Evolution of a Magnetic Flux Tube in a Sunspot Penumbra

Thick penumbra in a magnetostatic sunspot model

The conjecture that energy transport in sunspot penumbrae occurs through convection by an interchange of magnetic flux tubes is used in order to construct a magnetostatic model for a deep penumbra which is part of a global sunspot model. The model describes an overall mechanical equilibrium between the three stratifications: of the umbra, the penumbra, and of the solar convection zone, all of t...

Field - Free Gaps near Τ = 1 in Sunspot Penumbrae ?

The vertical stratification of the magnetic field strength in sunspot penumbrae is investigated by means of spectropolarimetric observations at high spatial resolution from the Hinode spacecraft. Assuming that the magnetic field changes linearly with optical depth we find that, in those regions where the magnetic field is more inclined and the Evershed flow is strongest (penumbral intraspines),...

Heat transfer in sunspot penumbrae Origin of dark-cored penumbral filaments

Context. Observations at 0. 1 have revealed the existence of dark cores in the bright filaments of sunspot penumbrae. Expectations are high that such dark-cored filaments are the basic building blocks of the penumbra, but their nature remains unknown. Aims. We investigate the origin of dark cores in penumbral filaments and the surplus brightness of the penumbra using an uncombed penumbral model...

Theoretical Models of Sunspot Structure and Dynamics

Recent progress in theoretical modeling of a sunspot is reviewed. The observed properties of umbral dots are well reproduced by realistic simulations of magnetoconvection in a vertical, monolithic magnetic field. To understand the penumbra, it is useful to distinguish between the inner penumbra, dominated by bright filaments containing slender dark cores, and the outer penumbra, made up of dark...

Structure of proper motions in a sunspot penumbra