Dissertation

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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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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Understanding the solar meridional flow is important for uncovering the origin of the solar activity cycle. Yet, recent helioseismic estimates of this flow have come to conflicting conclusions in deeper layers of the solar interior, i.e., at depths below about 0.9 solar radii.

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For terrestrial climatology, the continuous measurement of the total (TSI) and spectral solar irradiance (SSI) between the EUV and IR spectral regions is of great importance.

Since 2008, the EUV region has been covered by the measurements of SolACES (Solar Auto Calibrating EUV Spectrometer)...

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Large-scale poloidal flow cells as formed by turbulent convection in stars are an integral part of stellar interior dynamics. Since large-scale flows reside predominantly in the deeper layers of the convection zones of stars, they are difficult to detect and characterize. Asteroseismology, the...

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Context
Our Sun is an unique high-energy plasma physics laboratory, which can be studied with exceptional spatial and temporal resolution. Using dedicated telescopes, it is possible to verify and enhance our knowledge about aspects of modern physics unaccessible to any experiments on earth. State of...

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Abstract 

Context. The dynamic atmosphere of the Sun exhibits a wealth of magnetohydrodynamic (MHD) waves. In the presence of strong magnetic fields, most spectacular and powerful waves evolve in the sunspot atmosphere. Allover the sunspot area, continuously propagating waves generate strong...

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Die vorliegende Arbeit stellt einen neuen Ansatz, der auf der Spektropolarimetrie des CrH- Moleküls beruht, zur Bestimmung der Magnetfelder der Sterne mit geringer Masse und der Braunen Zwerge vor. Die Wirksamkeit des Ansatzes wird am Beispiel des Braunen Zwergs LSR J1835+3259 demonstriert. Dieser,...

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The measurement of the velocity field of the plasma at the solar surface is a standard diagnostic tool in observational solar physics. Detailed information about the energy transport as well as on the stratification of temperature, pressure and magnetic fields in the solar atmosphere are encoded in...

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Helioseismic investigations of acoustic waves propagating through the Sun have given astonishing insights about the structure of the solar interior and its rotation in recent years. But still there are many open questions, especially concerning dynamical processes in the interior that are related to...

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