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Paper: Solar Cycle Variations of the Second Solar Spectrum
Volume: 489, Solar Polarization 7
Page: 167
Authors: Bianda, M.; Ramelli, R.; Gisler, D.; Stenflo, J. O.
Abstract: The average strength of the spatially unresolved turbulent magnetic field in the Sun's photosphere can be measured with the Hanle effect. The possible variations of this average value over time scales of a solar cycle is the topic of an ongoing synoptic program at IRSOL that was started in 2008. The scattering polarization of C2 molecular lines around 5140 Å is regularly measured, typically once per month. These lines allow the application of the differential Hanle effect to determine the turbulent field strength. Here we report about the behavior of the determined field strength during the beginning active phase of the solar cycle and about our intention to start a new synoptic program based on the Hanle effect in the Sr I 4607 Å line, with which turbulent field strengths are found that are an order of magnitude larger than those determined with the molecular C2 lines. These synoptic programs allow us to explore the nature of the magnetic fields at the small-scale end of the magnetic scale spectrum and to determine the possible role of a local dynamo for the generation of these fields.
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