Browsing Fakultät für Physik (inkl. GAUSS) by Referee "Reiners, Ansgar Prof. Dr."
Now showing items 1-20 of 30
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High Precision Spectroscopy of the Solar Surface
(2024-06-17)Context: High-precision spectroscopy of the resolved solar surface provides benchmark observations for a vast field of stellar research. The solar spectrum exhibits variations from the disc centre to the limb. Observing ... -
Primordial Magnetic Fields: Evolution and Signatures
(2024-05-21)Magnetic fields permeate our Universe on all cosmic scales: from planets and stars to the large-scale fields found in galaxies and galaxy clusters. Different observational methods, such as the ones using the Faraday rotation ... -
Exoplanet Atmosphere Characterization with High-Resolution Doppler Spectroscopy
(2023-03-24)Ultra-hot Jupiters (UHJs) are a class of giant strongly irradiated exoplanets with dayside temperatures exceeding 2200 K. Due to their elevated temperatures, these objects are prime targets for atmospheric characterization ... -
How does stellar convection impact the detection of small planets at high radial velocity precision?
(2022-08-15)One of the big driving forces behind exoplanet research is the search for an Earth-twin to answer the old question of whether or not humanity is alone in the universe. According to simple logic as well as our current ... -
Analysis of solar faculae using stray-light-corrected spectropolarimetric data and numerical simulations
(2022-04-28)The objective of this thesis is to develop methods to improve the quality of restored ground-based observations, and to use such restored observations, along with 3D radiative MHD simulations, to study the properties of ... -
Activity of M dwarfs in the CARMENES sample
(2021-11-16)The Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs (CARMENES) has been searching and finding planets for five years by looking for periodic Doppler-shift ... -
Laser Frequency Combs for High Resolution Spectrograph Calibration
(2021-10-28)While laser frequency combs (LFCs) are in principle ideal calibration light sources for high resolution spectrographs, they are still not regularly used. This is not only due to high cost and maintenance, but also persistent ... -
Realistic MHD simulations of spots on cool main-sequence stars
(2021-08-09)Sunspots are cool, dark features on the solar surface consisting of two distinct parts - the inner dark umbra and its surrounding brighter, filamentary penumbra. Strong, nearly vertical magnetic fields found in the umbra ... -
Understanding the brightness variations of Sun-like stars on timescales of stellar rotation
(2021-01-21)Solar brightness varies on timescales from minutes to decades. In particular, the observed photometric variability can directly relate to the rotation period. Our understanding of this link allows extrapolations from the ... -
High resolution scattering spectropolarimetry of the quiet solar photosphere
(2021-01-14)In this thesis we investigate small-scale scattering polarization signals in quiet, internetwork (IN) regions of the lower solar atmosphere. Small-scale polarization signals are inherently hard to observe due to their ... -
Analysis of Space Weather Impacts on the Terrestrial Ionosphere and Development and Testing of a Coronagraph for Space Weather Forecasts
(2020-07-22)The ionosphere is a conductive layer of the Earth's atmosphere, characterised by the presence of free electrons. Through interaction with electromagnetic waves, it influences a wide spectrum of radio wave communications, ... -
Analysis of Coronal Mass Ejection Kinematics and Dependencies on Source Region Properties
(2020-02-24)Coronal Mass Ejections (CMEs) are outbursts of coronal plasma bound in magnetic structures that are explosively accelerated. Their evolution into the heliosphere can be observed with coronagraphs and heliospheric imagers, ... -
Star-Planet Interactions: Emission Spectroscopy of H$_{3}^{+}$ in Extrasolar Giant Planet Atmospheres
(2019-08-26)Extrasolar giant planets (EGP) in a close-in orbit undergo extreme irradiation by their host star. Emission of H$_{3}^{+}$ is expected to support the stabilization of the planetary atmosphere, since the ion radiates in the ... -
Precision Spectroscopy on OH
(2019-06-14)This thesis describes the implementation of a high precision laser system which, as a first demonstration of its capabilities, has been used to measure electronic transitions from the X²Π₃⸝₂, v''=0, J''=3/2 rovibronic ... -
White-Light Mass Determination and Geometrical Modelling of Coronal Mass Ejections
(2019-01-21)Coronal Mass Ejections (CMEs) are explosive large-scale outbursts of the Sun’s coronal plasma and magnetic field. They can induce strong geomagnetic storms at Earth, which pose serious threats to space systems, communications ... -
The solar wind’s geomagnetic impact and its Sun--Earth evolution -- Predictive models for space weather and the Parker Solar Probe orbit
(2018-11-06)This thesis addresses two current topics in solar wind research and space weather. The first study is dedicated to the solar wind's impact on geomagnetic activity and the second study to the estimation of the solar wind ... -
Solar Variability over the Last 9000 Years
(2018-08-31)The solar activity has been observed to vary at various time scales, of which the 11-year solar cycle is the most prominent one. Since the Sun provides the main external energy to the Earth, knowledge of solar variability ... -
Dynamics of Suspended Dust Grains: Experimental Investigations and Implications for Protoplanetary Discs
(2018-05-29)The collective interaction of solid particulate matter with flowing gas is one of the fundamental processes occurring in planet-forming discs. Small dust grains and pebbles are comparable to or smaller than the mean ... -
Radial velocities in low mass stars: improving the wavelength solution of astronomical spectrographs and understanding stellar noise
(2017-11-10)The radial velocity method has been used to discover hundreds of extrasolar planets in the past two decades. The continuous improvements in radial velocity precision have revealed several rocky planets in the habitable ... -
Modelling turbulent effects of stellar feedback in cosmological simulations
(2017-10-30)In order to study the influence of turbulence on star formation, stellar feedback, and the mixing of metals into the circumgalactic medium (CGM), we implemented a model for star formation and stellar feedback and employ ...