Presentasjon av masteroppgave: Masoumeh Izadparast

Multi-wavelength observations of magnetic bright points in the lower solar atmosphere


Magnetic bright points (MBPs) are small-scale (generally kG) magnetic features, ubiquitous in the lower solar atmosphere, and are a manifestation of solar magnetism. They represent the cross-sections of thin flux tubes in different heights. These flux tubes are generated by the advection of magnetic lines from the body of granules into their boundaries in intergranular areas. Due to the convective collapse along magnetic field lines and compression of the bundles, the magnetic field is intensified. The hot and opaque plasma in the deeper layers within the flux tube radiates from the walls, and therefore, a MBP appears bright in the base of photosphere.

In this thesis, we observed MBPs in four different passband filters sampling different heights in the solar atmosphere. Using high-spatial and high-temporal resolution datasets taken with the Solar Swedish Telescope (SST), we study the physical and dynamical properties of MBPs in a quiet sun region close to the solar disk center.

The MBPs were detected using a semi-automated algorithm, which comprises a manual selection and an automated detection algorithm using a scheme of iterative solutions. They were further traced in time-series of images by means of a tracking algorithm. The advantages of applying this method to identify MBPs are to prevent misidentification of MBPs from other non-magnetic bright features. With the help of these algorithms, we extracted physical (such as, size and brightness) and dynamical (such as, horizontal velocity and lifetime) quantities of the identified MBPs. The extracted parameters were analyzed and discussed afterwards.

The analysis of outcomes indicates that the MBPs observed in the lower photosphere live longer and have smaller size on average, while the MBPs residing in the upper photosphere/low chromosphere have found to be brighter in this study. We found that size and brightness of the MBPs are significantly correlated. Our analysis also revealed a direct correlation between lifetimes and maximum intensities of the studied MBPs.

Veileder: Professor Van Der Voort Luc Rouppe, Institutt for teoretisk astrofysikk, UiO

Medveiledere: Postdoktor Pia Zacharias, Postdoktor Shahin Jafarzadeh, Institutt for teoretisk astrofysikk, UiO

Intern sensor: Professor David F. Mota, Institutt for teoretisk astrofysikk, UiO

Ekstern sensor: Forsker, Jaime de la Cruz Rodriguez, Institute for Solar Physics, AlbaNova University Center, Stockholm Sweden

Publisert 2. des. 2015 15:32 - Sist endret 11. des. 2015 09:12