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 16 of 16 for “"Chromosphere"”.
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Analysis and Modelling of a Type II White-light Solar Flare
… at least part of their energy in the upper chromosphere where hydrogen lines are formed. Instead, the models suggest that the beams penetrate through the upper chromosphere and deliver their energy directly into the lower chromosphere. Such beams can be dominated by both electrons and/or …
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Generation and propagation of longitudinal tube waves in late-type stellar atmospheres and the rotation-emission activity relation
… heating the outer layers. The response of the chromospheres of the Sun and two late-type stars (of spectral types F5V & M0V) to the excitation by different wave modes was studied. It was found that the magnetic atmosphere shows resonance oscillations with longer periods in comparison with the …
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The Structure and Dynamic nature of the Solar Atmosphere
… of a 5-mm p-mode propagating through the chromosphere, transition region and into a coronal loop. Fourthly, an observing campaign is designed and executed to probe the connectivity between the chromosphere, transition region and corona within active regions. Oscillations within the 3-min …
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Image enhancement techniques applied to solar feature detection
… solar disk features. In each picture, the solar chromosphere filaments are identified for further evolution examination. The initial preprocessing step involves local thresholding to convert grayscale images into black-and-white pictures with chromosphere granularity enhanced. An alternative …
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Modelling line emission in the lower 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 for line emission are required for the …
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Understanding the energy balance of TR structures observed by IRIS in non-equilibrium emission
… the thin boundary layer connecting the cooler chromosphere to the hotter corona, named the TR, is an important step toward understanding mass and energy transport from the chromosphere to the corona. Thus, spectral emissions from the cool (< 1 MK) loop-like structures in this region are in need …
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Atmospheric responses to flare generated sunquakes
… photosphere were creating the wavefronts in the chromosphere. Combining the datasets to create a single dataset allowed a time-distance diagram to be created, which meant the apparent transverse velocities and accelerations of the SQ could be derived. The velocity of the wavefront ranged from 4.5 …
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New facet of solar activities revealed by high-resolution imaging at he i 10830 Å
… which are mainly present in the upper solar chromosphere or lower corona, providing the information in the interface layer. Second, the triplet is optically thinner than other chromospheric lines, such as H[alpha] 6563 [Angstrom] or Ca II 8542 [Angstrom], making the photosphere visible as a …
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High resolution observations of magnetohydrodynamic shocks in the solar atmosphere
… boundary between the upper photosphere and lower chromosphere. This work uncovers first-time evidence of the manifestation of chromospheric intermediate shocks in sunspot umbrae, providing a new method for the potential thermalization of wave energy in a range of magnetic structures, including …
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Electron acceleration in a flare plasma via coronal circuits
… generation of hard X-ray radiation in the dense chromosphere. The previously described idea is modelled and investigated by means of electric circuits. For this the microscopic plasma parameters, the magnetic field geometry and hard X-ray observations are used to obtain parameters for modelling …
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Design and application of near infrared tunable filter for ATST and NST
… magnetic reconnection in photosphere and lower chromosphere may only take place at an atmospheric level lower than 5000 km, instead of the height where fast solar wind is believed to generate (between 5000~20000 km). The science deduced based on these observations could be greatly improved by …
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Development of advanced algorithms to detect, characterize and forecast solar activities
… consists of a mass of gas suspended over the chromosphere by magnetic fields and seen as a dark, ribbon-shaped feature on the bright solar disk in H[alpha] (Hydrogen-alpha) full-disk solar images. In this dissertation, an automatic solar filament detection and characterization method is …
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Catastrophic cooling in solar coronal loops : thermal instability as a road to complex evolution
… by coronal heating from the cool and dense chromosphere into the corona, then condenses in the coronal part of the loop as a result of thermal instability, drains towards the footpoints of the loop and finally evaporates again. When applying the catastrophic cooling scenario to long active …
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High resolution solar observations from first principles to applications
The expression "high-resolution observations" in Solar Physics refers to the spatial, temporal and spectral domains in their entirety. High-resolution observations of solar fine structure are a necessity to answer many of the intriguing questions related to solar activity. However, a researcher …
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Magnetic reconnection in small and large scales on the sun
Almost all solar activities observed are related to the solar magnetic field, especially the topological restructuring of magnetic fields, the so-called magnetic reconnection in solar physics. They are occurring at different scales related to various phenomena, during minimum or maximum of the …