Presentasjon av masteroppgave: Elisabeth Helen Fjeldsbø Jordahl
Investigation of Dynamic Fibrils in H-Alpha 6563 and CA II 8542
Dynamic fibrils (DFs) are a subset of dynamic jets in the lower solar atmosphere, that move up and down along magnetic field lines on the solar disk. Jet-like features have been observed at the solar limb for more than one hundred years, so it is important to find out whether the dynamic fibrils have any physical association to the limb features. Recent developments of observational instruments and post-processing imaging techniques have allowed for advances in image resolution, making on-disk features easier to distinguish and investigate.
In this thesis the properties of dynamic fibrils in the chromosphere will be studied through analyzing the spectral lines hydrogen alpha (H-α) and calcium II 8542 (Ca 8542). These two lines sample slightly different layers of the solar atmosphere. The data set under examination was acquired with the CRISP instrument at the Swedish 1-m Solar Telescope (SST) on La Palma. The dynamic fibrils observed in this data set, are obtained from a small active region, that contains small pores with a lot of dynamic activity.
The research of this thesis will be carried out under the assumption that dynamic fibrils move in parabolic paths, like it has been shown from De Pontieu et al. (2007a), Hansteen et al. (2006) and Langangen et al. (2008b). The thesis will expand on the work of De Pontieu et al. (2007a), Langangen et al. (2008b), and Langangen et al. (2008a), since analysis will be done not only for H-α, but also for Ca 8542. The work will follow analysis methods similar to these papers, but optimized for the data set under investigation.
The main goals of this research will be to advance upon what has already been discovered regarding dynamic fibrils, by firstly confirming certain properties, and secondly to investigate their evolution in the two spectral lines.
From a sample of 50 dynamic fibrils, results confirm the parabolic trajectories of the dynamic fibrils, both in H-α and Ca 8542. Their paths appear clearer in H-α, while in Ca 8542 they can appear more diffuse. The mean properties (such as lifetime, maximum height, velocity and deceleration) of the dynamic fibrils are quite similar in both H-α and Ca 8542. It was found that the general properties ofthe dynamic fibrils in this study generally agree with what was found in previous studies.
Veileder: Luc Rouppe van der Voort
Intern sensor: Per B. Lilje
Ekstern sensor: Dan Kiselman, Stockholms universitet, Sverige