Polarity reversals
(Awkward title for a very exciting issue).
The satellite Hinode has recently revealed penumbral structures with a magnetic polarity opposite to the main sunspot polarity (see this paper). They may be a direct confirmation of magnetic field lines and mass flows returning to the solar interior throughout the penumbra, a configuration previously inferred from interpretation of observed Stokes profile asymmetries by MISMA inversion (see this paper).
We have a paper where put forward the connection bewteen these two observations: see it here. Among other things, this paper predicts that the dark cores in penumbral filaments coincide with the polarity reversals, as it is explained in this review paper. Even if the conjecture turned out to be incorect, the paper is interesting because it summarize a list of observables that any proper model of the penumbra must satisfity (and none does it so far).
