Description
(Short description)
As local magneto-convective phenomena, magnetic elements are present at all latitudes on the Sun, but are not uniformly distributed. On the large scale, we find them mostly within the two main global components of the photospheric magnetism: the active regions and the magnetic network. Active regions are large bipolar regions formed by the emergence of flux loops, characterized by the presence of Sunspots at their footpoints. There, magnetic elements have the largest number density and form bright clusters dubbed plages.
(Text)
When observed from the disk center to the limb, small-scale magnetic features in the photosphere exhibit an increase in brightness contrast (i.e. relative to quiet surroundings) along with a change in appearance from Bright Points (BPs) to faculae. The work presented in this dissertation has been dedicated to the investigation of the center-to-limb variation (CLV) of both the appearance and brightness of these small-scale magnetic features, based on images and spectro-polarimetric data at a very high spatial resolution. The goals were to provide novel observational constraints for MHD models and a deeper understanding of the relationhip between the features appearing as Bright Points (BPs) and faculae. To study the variation of appearance, a photometric method based on Linear Discriminant Analysis was developed to classify BPs and faculae at various heliocentric angles. This allowed the determination of a CLV of the relative number of BPs and faculae as well as the statistical analysis of their brightness and morphology. Spectro-polarimetric scans at a constant spatial resolution (Hinode satellite) were then used to assess the dependence of the continuum contrast of magnetic features on both the heliocentric distance and on magnetic parameters inferred by inversions.
