Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 35 for “"Solar atmosphere"”.
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Modelling line emission in the lower solar atmosphere
The transition region in the solar atmosphere bridges the lower temperature, higher density chromosphere at the base with the tenuous, high temperature plasma in the corona. It undergoes a change in temperature from 25000K to about 600000K. Plasma conditions mean that fundamentally different models …
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The Structure and Dynamic nature of the Solar Atmosphere
… of dynamic phenomena present throughout the solar atmosphere, from the photosphere to the corona. Above the photosphere, where the plasma fi is small, the emitting plasma structure and dynamics are tied intimately to the solar magnetic field. Firstly, a wavelet analysis is applied to …
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High resolution observations of magnetohydrodynamic shocks in the solar atmosphere
… forms of magnetohydrodynamic shocks in the solar atmosphere. Simultaneous slit-based spectro-polarimetry and spectral imaging observations of the chromospheric He I 10830 A and Ca ˚ II 8542 A lines is employed to examine fluctuations in the ˚ umbral magnetic field caused by the steepening of …
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A state-space approach to dynamic tomography
… is significant and governed by a physical model. Solar tomography, the remote sensing problem concerned with the reconstruction of the dynamic solar atmosphere, has served as the motivating application throughout the development of the dissertation. The proposed state-space formulation provides a …
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EUV Spectroscopy of Solar Active Region Jets
Title : EUV Spectroscopy of Solar Active Region Jets Abstract : The million degree temperature of the solar corona has been a continuing puzzle to scientists. A detailed study of energetic events such as solar flares, coronal mass ejection and solar jets may provide important clues about how …
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Mathematical Models of Quiescent Solar Prominences
<p>Magnetic fields in the solar atmosphere suspend and insulate dense regions of cool plasma known as prominences. The convection zone may be the mechanism that both generates and expels this magnetic flux through the photosphere in order to make these formations possible. The connection is …
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NONLOCAL AND NONLINEAR EFFECTS ON SOLAR OSCILLATIONS (RADIATIVE DAMPING, LIMB DARKENING).
This work investigates the response of the solar atmosphere to mechanical and thermal driving due to global solar oscillations. It was discovered that the coupling of thermal and mechanical modes was very important in reconciling theoretical predictions of the expected change in the solar limb due …
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Solar flare gamma-ray spectroscopy with CGRO-COMPTEL
<p>The X-ray and gamma-ray emission from solar flares provides important information about high-energy particles in solar flares. Energetic protons and ions interact with the solar atmosphere, giving rise to nuclear line emission at MeV energies and higher energy photons from the decay of neutral …
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PROPERTIES AND CORRELATION OF FLARES AND CORONAL MASS EJECTIONS AND THEIR POSSIBLE RELEVANCE ON THE SOUTHERN NIGHT SKY BACKGROUND : A STATISTICAL STUDY
This Thesis is devoted to a statistical study of solar phenomena (flares and coronal mass ejections) and their possible effects on the Earth. The Sun, our star, can be considered a huge laboratory where we can study the interaction of a ionized gas with magnetic fields. In particular, the solar …
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A comprehensive study of evolution of photospheric magnetic field and flows associated with solar eruptions
… been recognized as an important element of the solar flare process. Recent theoretical work has shown that such a change would imply Lorentz force perturbations acting on both the outer solar atmosphere and the solar surface. This research uses vector magnetograms obtained with the Helioseismic …
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Analysis and Modelling of a Type II White-light Solar Flare
… flares (WLFs) are rare impulsive events in solar atmosphere observed across the electromagnetic spectrum, but without the characteristic emission in hydrogen lines. A unique set of multi-instrument observations is presented with broad wavelength range spectra in the visible and UV range. …
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Braiding of Coronal Loops and Consequences for Coronal Heating
… increase which occurs as we move up through the solar atmosphere into the corona. Theories abound, including that of heating via reconnection, following the formation of current layers, which occur as the coronal field is braided by photospheric footpoint motions. In this work we designed …
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Analysis of the penumbra formation in sunspots
… the magnetic field in different layers of the solar atmosphere. Its study requires long time series of observations carried out with high temporal, spatial, and spectral resolution. Moreover, due to few available datasets of this phase of the sunspot evolution, the physical processes at the …
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High resolution solar observations in the context of space weather prediction
… to study and monitor active regions on the solar surface and ultimately to predict space weather based on the Sun's activity. In this study, a system that uses the full power of speckle masking imaging by parallel processing to obtain high-spatial resolution images of the solar surface in …
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Solving the system of Radiation Magnetohydrodynamics : for solar physical simulations in 3d
… this system is used to model the plasma in the solar convection zone and in the solar photosphere. It is a non--linear system of balance laws derived from the Euler equations of gas dynamics and the Maxwell equations; the energy transport through radiation is also included in the model. <br>The …
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Low coronal signatures of coronal mass ejections: coronal “waves” and dimmings
… of magnetised plasma that explode from the solar atmosphere. This thesis focuses on understanding the nascent stages of CMEs, and their magnetic development as they expand into the interplanetary space of our solar system. This is an important part of our effort to understand the space …
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Numerical simulations of radiation and heating from non-thermal electrons in solar flares
… from magnetic loops in active regions of the solar atmosphere using numerical simulations. The simulations also allow investigation of Type III radio emission. In our model we vary a number of physical parameters such as magnetic field configuration and density models, investigating the effect …
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The 3-D topology of magnetic fields in and around sunspots
The most prominent features on the surface of the solar disc are the sunspots, which have been studied since their detection in the 17th century. Despite this years and centuries of scientific investigations, surprisingly many facets of sunspots are not well understood. In this thesis, the …
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