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When observing Active Regions, a variety of different structures can be identified on the solar surface. Among them are the umbra and penumbra of sunspots, pores, orphan penumbrae, etc. In each of these, the moving solar plasma and the magnetic field interact in a different way and convection is...

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Sunspots play an important role in understanding the dynamical nature of the solar magnetic field. Although their surface appearance has been observed for over four centuries, little is known about the subsurface structure. Sunspots are known to strongly influence solar acoustic modes and there is a...

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Mit zunehmender Größe der Apertur eines Teleskops steigt auch die theoretisch mögliche Auflösung der Beobachtung. Dies führt dazu, dass kleinere Strukturen und Phänomene beobachtet werden können, welche bisher unentdeckt blieben. Mithilfe des GREGOR-Teleskops können nun Aufnahmen gemacht werden, die...

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Standard algorithms for tracking small scale magnetic features suffer
from ambiguities due to the intrinsic complexity of the feature
interactions which are driven by photospheric convective motions.

In his Ph.D. work, Andrei Gorobets will work on an alternative concept
for tracking the evolution...

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The Sun is a sphere of hot plasma which rises from the bottom of the convection zone up to the photosphere. It is only at inside this layer that the solar atmosphere becomes transparent for radiation, which is why the photosphere is also called the surface of the Sun. It is covered by a pattern of 5...

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The topic of this thesis are the changes to spectral line profiles observed in varying heights of the solar atmosphere. Gas motions in the atmosphere manifest as Doppler shifts and asymmetries in the line profiles. These changes vary over the solar disk, depending on the conditions of the line...

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Im Rahmen meiner Bachelorarbeit habe ich einen Protosonnenfleck untersucht, um zu studieren, welche Plasmaströme vor der Bildung von Penumbra sichtbar sind, und wie sich verschiedene polarimetrische Parameter vor und während der Bildung verändern.

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Estudio sobre la búsqueda de criterios de estabilidad de concentraciones magnéticas en la atmósfera solar.

This master thesis resulted from a collaboration of KIS and IAC, and was submitted to the University of La Laguna (Spain).

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Formation of Intergranular Lanes and Acoustic Events

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The vertical component of the magnetic field B⊥ was determined and evaluated at the boundary between the penumbra and the umbra for 11 fully developed sunspots observed with the GRIS@GREGOR instrument.

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Context. Understanding the solar activity cycle - its origin, the mechanisms that drive it, and its relation to stellar activity cycles - is an outstanding open issue in solar and stellar astrophysics. Helio- and asteroseismology have developed into powerful tools to gain insight into the interior...

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Context. Jurcak et al. (submitted to A&A) found no dependence of the vertical magnetic field component <|Bver|>ψ at the umbral boundary of sunspots on area in their statistical study of 79 active regions, whereby <.>ψ stands for average along the contour.

Aims. We investigate the temporal...

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This doctoral dissertation is primarily focused on the study of the solar atmosphere, the outermost part

of our Star. The main goal of this work is to improve our understanding of the solar atmospheric structure using helioseismic methods. The research conducted for this thesis is based primarily...

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Die meridionale Strömung im Sonneninneren ist wichtig, um den Ursprung des Aktivitätszyklus der Sonne zu erklären. Neueste helioseismische Schätzungen dieser Strömung kommen jedoch zu konträren Ergebnissen in Schichten tiefer als etwa 0,9 Sonnenradien.

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