Description
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Solar corona consists of low-density plasma, which is highly structured by the magnetic field. Observations of the corona show a wide variety of structures with sizes ranging from the Suns diameter to the limit of the angular resolution. Polar plumes are the structures tracing out the open field lines starting from the surface of the Sun and extending super-radially into the heliosphere. Plumes 3D geometry, formation, and contribution to other solar phenomena are still under investigation. In this dissertation, advance mathematical techniques are developed to detect plumes and to reconstruct their 3D structure: (i) a multiscale identification method based on Hough-wavelet analysis; (ii) tomography using the filtered back projection and including the differential rotation of the Sun; and (iii) a conventional stereoscopic triangulation method. Polar plumes are then studied in a sequence of Solar Extreme Ultraviolet images taken by the three spacecraft telescopes STEREO/EUVI A and B, and SoHO/EIT. By measuring the projected plume orientation we characterize the large scale magnetic field: the opening of the polar cap magnetic field is identified as well as the inclination of the polar cap relative to the solar rotation axis. The plume 3D reconstruct allow us to investigate whether plumes have a near-circular cross section, curtain-like structures, or they follow a network pattern. Also, by knowing their 3D location and orientation, we discuss their lifetime, their distribution over the polar cap, and their possible association of with coronal jets.
