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 38 for “"photosphere"”.
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Spectroscopy of small scale magnetic structures in the solar photosphere
… in the convective flow field of the <br>solar photosphere. <br>As manifestations of small scale magnetic fields, bright points become <br>important for the understanding of the coronal heating process and the <br>variability of the solar irradiance. <br>Hitherto all observations of this fine …
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Computation and analysis of flow patterns in the solar photosphere.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1974.
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The behavior of hydrogen and helium at white dwarf photosphere conditions
… and theoretical developments. The White Dwarf Photosphere Experiment (WDPE) at Sandia National Laboratories Z-machine delivers laboratory data directed at solving the mass determination problems for WDs. For hydrogen line shapes, I find that fundamental assumptions regarding emission and …
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High resolution spectropolarimetric diagnostics of weak, small-scale magnetic fields in the solar photosphere
… of ‘hidden’ magnetic energy in the quiet solar photosphere, and unlocking an understanding of this phenomenon requires the study of magnetic activity on the smallest scales accessible to observations. With the advent of next generation high resolution telescopes, our understanding of how the …
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Mathematical Models of Quiescent Solar Prominences
… and expels this magnetic flux through the photosphere in order to make these formations possible. The connection is examined here by modeling the convection zone as both one-dimensional, then more realistically, two-dimensional.</p> <p>First a Dirichlet problem on a semi-infinite strip is …
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Particle acceleration at null-point current sheets in the solar corona
… arc where the dome structure intersects the photosphere, corresponding to observed circular f lare ribbons. The highest energy particles are guiding along flux rope field lines, replicating the bright ‘knots’ observed in circular flare ribbons and a bright point where the spine field lines …
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Electron acceleration in a flare plasma via coronal circuits
… electric potentials in the active regions in the photosphere. Usually these electric potentials are associated with electric currents closed within the photosphere. However as a result of magnetic reconnection, a magnetic connection between the regions of different magnetic polarity on the …
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Solving the system of Radiation Magnetohydrodynamics : for solar physical simulations in 3d
… 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 starting point of our presentation is a …
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Study of magnetic helicity in solar active regions and its relationship with solar eruptions
… tion of magnetic helicity injected through the photosphere of active regions was examined related to 46 CMEs and two active-region coronal arcades building up to CMEs. The main findings in this dissertation are as follows: (1) the study of magnetic helicity for active regions producing major …
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Studies of solar white-light flares and small-scale magnetic structures observed in the near infrared
… are good proxy of the deepest layer of the solar photosphere. I made fundamental contributions in two areas of near infrared (NIR) solar physics: (1) the first detection and understanding of white-light flares in the NIR and (2) clearly demonstrated non-existence of "dark faculae". Several …
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Spectroscopy of white dwarf stars observed by HETDEX.
… that can be treated independently: a thin photosphere and a degenerate core. Large-scale surveys, such as the Sloan Digital Sky Survey, have spectroscopically observed more than 40,000 white dwarfs to date, providing a large sample to be used in the evaluation of these theoretical models. …
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Astrophysical signatures of neutron stars in compact binaries and experimental improvements on gravitational-wave detectors
… wind and will dominate the composition at the photosphere after ~ 1 s. This may create detectable absorption edges in burst spectra and explain the observed transitions from super-expansions to moderate expansions. Gravitational-wave (GW) observatories such as Advanced LIGO (aLIGO) open up a …
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New facet of solar activities revealed by high-resolution imaging at he i 10830 Å
… how the convective motions and flows in the photosphere activate and drive solar activity in the corona. He I 10830 [Angstrom] imaging has proven to be an excellent choice for observing the interface region. First, the formation of 10830 [Angstrom] triplet requires extreme conditions which …
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NONLOCAL AND NONLINEAR EFFECTS ON SOLAR OSCILLATIONS (RADIATIVE DAMPING, LIMB DARKENING).
… in the analysis for single modes in the upper photosphere.
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The Structure and Dynamic nature of the Solar Atmosphere
… 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 multi-temperature spectroscopic …
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Braiding of Coronal Loops and Consequences for Coronal Heating
… to act as braiding motions on a numerical photosphere, and sought to establish how each one affected overlying coronal fields. We used the concepts of topological entropy and helicity to categorise the drivers and applied them to a uniform field representing a simple coronal loop. We found …
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Sweeprate and Temperature Effects on Crackling Noise
… the earth to the bursty release of energy in the photosphere of the sun dwarfing that of our most horrible WMD. Typically, crackling noise is modeled in the infinitely slow driving rate limit at zero temperature. In this dissertation I investigate the effects of relaxing these limits. First I …
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The Equilibria, Stability and Nonlinear Dynamics of Magnetically Sheared Atmospheres With Applications to the Solar Environment
… for impulsive shearing motions at the photosphere in newly emerged bipolar active regions. Simulations of instabilities of sheared magnetic arcades indicate that self-induced, shear Alfven waves coupled with magnetic buoyancy provide a powerful feedback mechanism that results in …
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Experimental investigation of the trigger problem in magnetic reconnection
… also be applicable to reconnection in the solar photosphere and the interstellar medium, where the ionization fraction is low. In these experiments, a plasma filament propagates across a magnetic field in a background of neutral atoms. The filament motion is driven by charge separation in an …
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Magnetic reconnection in small and large scales on the sun
… minimum or maximum of the solar cycle, from the photosphere to the solar corona. For small-scale activities, type II spicules which display high velocity upflows observed at the limb, have the most possible underlying driving mechanism of magnetic reconnection. A set of tools is developed for …
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