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Abstract: We describe a scenario for the topology of the magnetic field in penumbraethat accounts for recent observations showing upflows, downflows, and reversemagnetic polarities. According to our conjecture, short narrow magnetic loopsfill the penumbral photosphere. Flows along these arched field lines areresponsible for both the Evershed effect and the convective transport. Thisscenario seems to be qualitatively consistent with most existing observations,including the dark cores in penumbral filaments reported by Scharmer et al.Each bright filament with dark core would be a system of two paired convectiverolls with the dark core tracing the common lane where the plasma sinks down.The magnetic loops would have a hot footpoint in one of the bright filament anda cold footpoint in the dark core. The scenario fits in most of our theoreticalprejudices siphon flows along field lines, presence of overturning convection,drag of field lines by downdrafts, etc. If the conjecture turns out to becorrect, the mild upward and downward velocities observed in penumbrae mustincrease upon improving the resolution. This and other observational tests tosupport or disprove the scenario are put forward.

Author: J. Sanchez Almeida Instituto de Astrofisica de Canarias, La Laguna, Tenerife, Spain

Source: https://arxiv.org/


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