Theoretical Models of Sunspot Structure and Dynamics
arXiv:0903.4106 · doi:10.1007/978-3-642-02859-5_17
Abstract
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 and bright filaments of comparable width with corresponding magnetic fields differing in inclination by some 30 degrees and strong Evershed flows in the dark filaments along nearly horizontal or downward-plunging magnetic fields. The role of magnetic flux pumping in submerging magnetic flux in the outer penumbra is examined through numerical experiments, and different geometric models of the penumbral magnetic field are discussed in the light of high-resolution observations. Recent, realistic numerical MHD simulations of an entire sunspot have succeeded in reproducing the salient features of the convective pattern in the umbra and the inner penumbra. The siphon-flow mechanism still provides the best explanation of the Evershed flow, particularly in the outer penumbra where it often consists of cool, supersonic downflows.
To appear in "Magnetic Coupling between the Interior and the Atmosphere of the Sun", eds. S.S. Hasan and R.J. Rutten, Astrophysics and Space Science Proceedings, Springer-Verlag, Heidelberg, Berlin, 2009
References in corpus (12)
- Radiative MHD simulation of sunspot structure
- 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
- Convection and the origin of Evershed flows in sunspot penumbrae
- A 3-D sunspot model derived from an inversion of spectropolarimetric observations and its implications for the penumbral heating
- Detection of sea-serpent field lines in sunspot penumbrae
- Are there field-free gaps near tau=1 in sunspot penumbrae?
- High-resolution proper motions in a sunspot penumbra
- Spectropolarimetery of umbral fine structures from Hinode: Evidence for magnetoconvection
- Penumbral models in the light of Hinode spectropolarimetric observations