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Paper: What are ‘Faculae’?
Volume: 369, New Solar Physics with Solar-B Mission
Page: 103
Authors: Berger, T.E.; Title, A.M.; Tarbell, T.D.; Rouppe van der Voort, L.; Loefdahl, M.G.; Scharmer, G.B.
Abstract: We present very high resolution filtergram and magnetogram observations of solar faculae taken at the Swedish 1-meter Solar Telescope (SST) on La Palma. Three datasets with average line-of-sight angles of 16, 34, and 53 degrees are analyzed. The average radial extent of faculae is at least 400 km. In addition we find that contrast versus magnetic flux density is nearly constant for faculae at a given disk position. These facts and the high resolution images and movies reveal that faculae are not the interiors of small flux tubes - they are granules seen through the transparency caused by groups of magnetic elements or micropores “in front of” the granules. Previous results which show a strong dependency of facular contrast on magnetic flux density were caused by bin-averaging of lower resolution data leading to a mixture of the signal from bright facular walls and the associated intergranular lanes and micropores. The findings are relevant to studies of total solar irradiance (TSI) that use facular contrast as a function of disk position and magnetic field in order to model the increase in TSI with increasing sunspot activity.
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