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- Title
Analytical Model of an Asymmetric Sunspot with a Steady Plasma Flow in its Penumbra.
- Authors
Solov'ev, A.; Kirichek, E.
- Abstract
A new exact analytical solution to the stationary problem of ideal magnetohydrodynamics is derived for an unipolar asymmetric sunspot immersed in a realistic solar atmosphere. The radial and vertical profiles of pressure, plasma density, and temperature in the visible layers of the sunspot are calculated. The reduction in plasma density in the magnetic funnel of the sunspot, corresponding to the Wilson depression, is also obtained. The magnetic structure of the sunspot is given analytically in a realistic way: a part of the magnetic flux of the sunspot approaches the surrounding photosphere at the outer edge of the penumbra. The magnetic field of the sunspot is not assumed to be axially symmetric. For the first time, the angular dependence of the physical variables in this model allows us to simulate not only a deviation from the circular shape of the sunspot, but also a fine filamentary structure of the sunspot penumbra. The Alfvén Mach number (the ratio of the plasma speed to the Alfvén speed) is zero at the center of the sunspot and rises slowly toward the periphery of the sunspot; this corresponds to the structure of the Evershed flow in the penumbra. The Evershed flow in our model is mainly concentrated in dark penumbral filaments, as is observed.
- Subjects
SUNSPOTS spectra; MAGNETOHYDRODYNAMICS; FIELD-effect transistors; SOLAR atmosphere; PLASMA density
- Publication
Solar Physics, 2016, Vol 291, Issue 6, p1647
- ISSN
0038-0938
- Publication type
Article
- DOI
10.1007/s11207-016-0922-1