A&A 471, 977-991 (2007)

Reza Rezaei, Oskar Steiner (Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, 79104 Freiburg, Germany)
Sven Wedemeyer-Böhm (Institute of Theoretical Astrophysics, Postboks 1029 Blindern, 0315 Oslo, Norway)
Wolfgang Schmidt (Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, 79104 Freiburg, Germany)
Bruce W. Lites (High Altitude Observatory, NCAR, P.O. Box 3000, Boulder, CO 80307, USA)

Hinode observations reveal boundary layers of magnetic elements in the solar photosphere

Aims. We study the structure of magnetic elements of network-cell interiors.
Methods. A quiet Sun area close to the disc centre was observed with the spectro-polarimeter of the Solar Optical Telescope on board of the Hinode space mission, which yielded the best ever achieved spatial resolution in polarimetric data of the Fe I 630 nm line pair. For comparison and interpretation, we synthesize a similar data set from a three-dimensional magneto-hydrodynamic simulation.
Results. Wend several examples of magnetic elements, either roundish (tube) or elongated (sheet), which show a central area of negative Stokes-V area asymmetry framed or surrounded by a peripheral area with larger positive asymmetry. This pattern was predicted on the basis of numerical simulations some eight years ago. Here, we observationally corm its existence for therst time.
Conclusions. We gather convincing evidence that this pattern of Stokes-V area asymmetry is caused by the funnel-shaped boundary of magnetic elements that separates the x concentration from the weakeld environment. On this basis, we conclude that electric current sheets induced by such magnetic boundary layers are common in the photosphere.

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