Now showing items 1-20 of 21

• #### A coronal loop in a box: From energy generation to coronal emission ﻿

(2023-03-17)
The corona is the outer atmosphere of the Sun. It contains an abundance of bright arcs that consist of hot plasma trapped by the magnetic field. These coronal loops are heated to temperatures far surpassing the solar surface ...
• #### Analysis of small scale solar magnetic fields using Hinode SOT/SP ﻿

(2014-07-23)
This thesis presents an analysis of small magnetic structures found in the solar photosphere. All the work presented in the following chapters is primarily based on data obtained from the spectropolarimeter aboard the ...
• #### Analysis of time series of solar-like oscillations - Applications to the Sun and HD52265 ﻿

(2011-08-25)
The study of stellar oscillations allows one to constrain the structure and dynamics of stellar interiors to a precision that cannot be achieved with other methods. This dissertation focusses ...
• #### Crustal thickness from seismic noise correlations in preparation for the InSight mission to Mars ﻿

(2018-08-31)
The formation of terrestrial planets is still poorly understood. Studying the interior of Mars by analysing seismic waves can help to answer questions about that process. In the absence of plate tectonics, Mars has retained ...
• #### Data Compression for Helioseismology ﻿

(2015-10-22)
Efficient data compression will play an important role for several upcoming and planned space missions involving helioseismology, such as Solar Orbiter. Solar Orbiter, to be launched in October 2018, will be the next ...
• #### Differential rotation in Sun-like stars from surface variability and asteroseismology ﻿

(2016-07-15)
Thanks to helioseismology we know the internal rotation of the Sun as a function of radius and latitude. The presence of a shear at the base of the solar convection zone is thought to play a key role in the generation of ...
• #### Follow-up and dynamical analysis of Kepler targets with transit timing variations ﻿

(2020-06-04)
The exact characterisation of planets, their host stars and the structure of their systems is an essential part of exoplanet research. This helps to understand the formation and evolution of planetary systems. Planets ...
• #### Helioseismic diagnostics of solar dynamics in the near-surface layers ﻿

(2022-02-08)
This thesis proposes to develop new helioseismic diagnostics of solar near-surface flows. In a first part, we discuss the interaction of solar seismic waves (sound waves) with small-scale turbulent convection. The treatment ...
• #### Inverse Problems in Local Helioseismology ﻿

(2020-08-04)
Helioseismology is the main tool to infer the physical properties in the solar interior. In time-distance helioseismology, measurements of wave travel times are extracted from the cross-correlation of the oscillation signal ...
• #### Magnetohydrodynamic Simulation of Reconnection in Turbulent Astrophysical Plasmas ﻿

(2016-08-31)
Turbulence is ubiquitous at large-Reynolds-number astrophysical plasmas like in the Solar corona. In such environments, the turbulence is thought to enhance the energy conversion rate by magnetic reconnection above ...
• #### Measuring vortical flows in the solar interior ﻿

(2015-09-28)
This thesis focuses on observations of the effects of rotation on solar convection at the length scales of supergranulation and larger (>30 Mm). Rotation drives vortical flows through the Coriolis force and causes anisotropic ...
• #### Modeling experiments in helioseismic holography ﻿

(2019-05-29)
This dissertation aims at developing a theoretical framework for the signal and noise in helioseismic holography which is mathematically rigorous and physically meaningful. A main focus of this dissertation is modeling the ...
• #### Non-axisymmetric Magnetic Flux Transport in the Sun ﻿

(2018-02-01)
The solar magnetic field drives a wide range of phenomena, from sunspots to flares and coronal mass ejections. This field is maintained against ohmic dissipation by means of a hydromagnetic dynamo. In recent years, evidence ...
• #### Observations of large-scale solar flows ﻿

(2021-04-13)
In this dissertation, several components of large-scale solar flows are studied observationally: solar equatorial Rossby waves (waves of radial vorticity), large-scale convection, and surface flows around active regions. ...
• #### On the Detection of Exomoons in Photometric Time Series ﻿

(2019-09-02)
One of the next big steps forward for exoplanet science would be the detection of moons around extrasolar planets. In this thesis I investigate the exomoon candidate around the exoplanet Kepler-1625 b. I estimate the ...
• #### Slender Ca II H fibrils observed by SUNRISE/SuFI ﻿

(2018-04-24)
This thesis is devoted to analyzing the morphological and oscillatory properties of slender \caiih{} fibrils (SCFs) in the lower solar chromosphere. The aim of this study is to deepen our understanding of the physical ...
• #### Solar surface flows during active region emergence ﻿

(2022-06-16)
The aim of this thesis is to improve our understanding of the emergence of magnetic flux in the form of active regions (ARs) to the solar surface. Active regions are concentrations of strong magnetic field at the surface ...
• #### Strong magnetic fields and unusual flows in sunspots ﻿

(2023-02-06)
This thesis presents a study of sunspots, which are the most prominent features observed on the solar surface. Their structure is governed by the magnetic field. The umbra and penumbra of sunspots harbor different strengths ...
• #### Studies of the radial gradient of rotation near the solar surface ﻿

(2018-02-16)
Continuous observations of solar oscillations over the last twenty years have provided an opportunity to investigate interior properties of the Sun and their variations over the last two solar cycles. In this thesis, I ...
• #### Theory of solar oscillations in the inertial frequency range ﻿

(2022-11-16)
Recent observations have revealed that we lack a fundamental understanding of the large scale (with spherical harmonic degrees $l < 60$) flows in the Sun. Flows at these large scales are strongly influenced by rotation. ...