Die Erzeugung und Dissipation von solaren Magnetfeldern

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The generation, evolution, and dissipation of cosmic magnetic fields is one of the fundamental problems in astrophysics. The Sun as the closest star offers the unique opportunity to gain understanding of how magnetic fields interact with dynamic plasma: it is the action of moving ionized gas that is crucial for generating magnetic field. The solar photosphere manifests the upper boundary of a convection zone of ionized plasma, from which magnetic fields emerge, escaping into interplanetary space. In the photosphere the magnetic fields exist on a large range of spatial scales: from magnetic elements with sizes of a few hundred km or less to sunspots which a typical diameter of 30 000 km.This project will take advantage of unique sources of data that allow to improve our understanding of solar magnetic fields: (1) We will analyze data from the 1m SUNRISE Solar telescope that flew on a stratospheric balloon in June 2009. This mission has acquired the best-ever spectropolarimetric data of the quiet Sun. These data will allow to analyze how magnetic field emerges, evolves and eventually dissipates. (2) At the German Vacuum Tower Telescope, in July 2009, we have witnessed the formation of a sunspot under excellent seeing conditions. We have observed the formation process with two spectro-polarimeters and imaging devices. This data set of extraordinary quality and completeness will allow to address the long standing problem of how magnetic field emerges to form sunspots.