Study of brightness profiles for different coronal structures

Extended coronal structures can be observed in white-light using coronagraphs or heliospheric imagers. These instruments observe the Thomson-scattered emission by the electrons of that feature. The scattered emission shows a dependence on the geometry between the Sun, the observer and the scattering structure. The maximum scattering efficiency is obtained on a circle whose diameter is equal to the distance between the Sun and the observer (called Thomson surface). The aim of this study is to investigate the brightness profile of different coronal features in terms of the Thomson-scattering geometry using data from the Wide-Field Imager for Solar Probe (WISPR) aboard Parker Solar Probe (PSP). Due to the special orbit of PSP, the size of the Thomson surface is constantly changing. Brightness curves are calculated for features with different properties, e.g. static structures such as helmet streamers, dynamic but compact structures such as streamer blobs and expanding structures such as coronal mass ejections. The results are then compared with raytracing simulations.