On the Expansion of Large and Small Flux Tubes with Height
In the solar photosphere magnetic features (e.g. magnetic elements, sunspots) are known to expand with height. In the case of sunspots this expansion is known to be very rapid, with the field forming an almost horizontal canopy. In this contribution we present new results on the superpenumbral canopy of sunspots based on fits to Stokes I and V profiles of infrared spectral lines. The new models take pressure balance across the boundary of the canopy field into account. This improvement leads to significantly lower canopy base heights than previously determined from similar data. The three investigated sunspots show rather similar canopy base heights.
Finally, we compare the sunspot results with the expansion of small flux tubes and find interesting similarities between magnetic features having magnetic fluxes that differ by 5–6 orders of magnitude.
Key wordspolarization magnetic fields sun: infrared radiation sunspots faculae flux tubes
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