Solar Magneto-atmospheric Oscillations

Solar Magneto-atmospheric Oscillations
Author: Marie Elizabeth Newington
Publisher:
Total Pages: 207
Release: 2013
Genre:
ISBN:

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Estimates of wave energy fluxes in the solar photosphere and chromosphere suggest that gravity waves carry more energy than co-spatial acoustic waves. This work presents an exploration of the upward propagation of gravity waves from the photosphere to the chromosphere, in a realistic model of the solar atmosphere. The purpose is to determine what happens to upward propagating gravity waves when they reach regions where the magnetic forces dominate. Wave motions are assumed linear and the atmosphere is static and horizontally invariant. Dispersion and ray diagrams provide insight into the mode con¬version mechanism. Numerical solution of the linear adiabatic wave equations quantify wave energy fluxes. The analysis shows that typically even weak magnetic fields cause the gravity wave to reflect back downwards as a slow magneto-acoustic wave well before the Alfven-acoustic equipartition level, and it fails to reach the chromosphere. However, highly inclined magnetic fields allow gravity waves to penetrate the equipartition level and experience substantial mode conversion to up-going Alfven waves, or field-guided acoustic waves. Wave energy fluxes are sensitive to the magnetic field orientation and short radiative damping times, but are insensitive to the magnetic field strengths over the range considered (lOG -100 G). The mode conversion pathways found in adiabatic analyses are preserved in the presence of damping. Mode conversion of gravity waves to Alfven waves is a possible pathway to the upper atmosphere for wave energy. The cause of the high frequency enhancement (the acoustic glory) in seismic power surrounding large active regions with complex field structures is not yet understood. This work presents an investigation of the properties of the seismic emission power and acoustic power of large active regions that have acoustic glories. Helioseismic holography is used to create seismic emission power maps for six large active regions with complex magnetic field structures. Acoustic glories are visible in high-frequency seismic emission power maps (5.0 mHz -7.0 mHz) for all active regions studied. The analysis of acoustic power about large active regions, in high and low frequency regimes, confirms behaviours that are consistent with the findings of previous analyses of smaller active regions. Several new properties of high frequency seismic emission power associated with large active regions are identified: The maximum enhancements in seismic emission and acoustic power occur at different spatial locations; acoustic glories are most prominent in seismic emission power maps in the 5.0 mHz -6.0 mHz bandwidth; the radius of the acoustic glory reduces as frequency increases; and the mean value of high frequency (above 5.0 mHz) seismic emission power for the active regions studied was enhanced at intermediate line-of-sight magnetic flux densities (50 G -300 G).

Waves and Oscillations in the Solar Atmosphere (IAU S247)

Waves and Oscillations in the Solar Atmosphere (IAU S247)
Author: International Astronomical Union. Symposium
Publisher: Cambridge University Press
Total Pages: 404
Release: 2008-06-12
Genre: Science
ISBN: 9780521874694

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Provides the latest summary on the solar coronal heating enigma and magneto-seismology of the solar atmosphere, for solar physics researchers.

Waves & oscillations in the solar atmosphere: heating and magneto-seismology : proceedings of the 247th Symposium of the International Astronomical Union held in Porlamar, Isla de Margarita, Venezuela, September 17 - 22, 2007

Waves & oscillations in the solar atmosphere: heating and magneto-seismology : proceedings of the 247th Symposium of the International Astronomical Union held in Porlamar, Isla de Margarita, Venezuela, September 17 - 22, 2007
Author: Robertus Erdélyi
Publisher:
Total Pages: 0
Release: 2008
Genre: Helioseismology
ISBN:

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Physics of the Sun and Its Atmosphere

Physics of the Sun and Its Atmosphere
Author: B. N. Dwivedi
Publisher: World Scientific
Total Pages: 294
Release: 2008
Genre: Science
ISBN: 9812832718

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This book presents a pedagogical, updated and modern view of the Sun from its interior to its exterior as well as the Sun?Earth system. Written by eminent scientists in solar physics, the chapters deal with recent advances in solar physics, seismic Sun, solar magnetic field, waves and oscillations, spectroscopic diagnostics of solar plasmas, partially ionized lower atmosphere, coronal heating, coronal mass ejections, radio Sun, solar wind, and the Sun?Earth system. Each chapter is fully illustrated and has a comprehensive reference list. The book covers all major topics in solar physics, and presents a rich menu to motivate graduate students who wish to pursue a solar physics research career.

Nuclear Science Abstracts

Nuclear Science Abstracts
Author:
Publisher:
Total Pages: 612
Release: 1976
Genre: Nuclear energy
ISBN:

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Solar Atmospheric Oscillations

Solar Atmospheric Oscillations
Author: John William Leibacher
Publisher:
Total Pages: 258
Release: 1971
Genre: Solar atmosphere
ISBN:

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Sunspots: Theory and Observations

Sunspots: Theory and Observations
Author: J.H. Thomas
Publisher: Springer Science & Business Media
Total Pages: 422
Release: 2012-12-06
Genre: Science
ISBN: 9401127697

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This volume contains the invited papers presented at the NATO Advanced Research Workshop on the Theory of Sunspots, held in Cambridge, England, 22-27 September 1991. The idea of holding this Workshop first arose during the Solar Optical Telescope work shop on Theoretical Problems in High-Resolution Solar Physics in Munich in 1985. At that meeting, separate discussion groups were formed to consider specific topics in solar physics. The discussion group on sunspots recommended that there be a meeting devoted to theoretical problems associated with sunspots, the motivation being the consensus that theory seemed to lag behind the observational evidence in our quest for a satisfactory un derstanding of the physics of sunspots. This recommendation was warmly received and the two of us were designated to organize the Workshop. Although the Workshop eventually took place later than originally envisioned, the de lay turned out to be fortunate and the timing of the Workshop was ideal for a number of reasons. There have been remarkable improvements in high-resolution observations of sunspots in the past few years, and many important new observational results were pre sented for the first time at this Workshop (by groups working at the Lockheed Palo Alto Research Laboratories, the Swedish and German telescopes in the Canary Islands, and the V. S. National Solar Observatory). Vector magnetographs and Stokes polarimetry have at last given us reliable measurements of the vector magnetic fields in sunspots.

Solar Surface Magnetism

Solar Surface Magnetism
Author: R. J. Rutten
Publisher: Springer Science & Business Media
Total Pages: 532
Release: 2012-12-06
Genre: Science
ISBN: 940111188X

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Observations of the solar magnetic field are largely confined to the radiation emitted from the photosphere, the thin layer of the solar atmosphere which we call "the solar surface". It is from solar surface observations that we must infer the internal structure and the internal magnetohydrodynamic processes that lead to the multitude of fascinat ing phenomena of solar magnetic activity, and from solar surface observations we must also infer the interplay of convection and magnetism that regulates field dispersal, drives the heating of the outer-atmospheric plasma, and generates the solar wind. There is much to be learned from solar surface magnetism in physics and astrophysics; currently, there are rapid developments in this exciting field. The workshop of which this volume contains the proceedings aimed at a synthesis between observers and theorists, both with regard to the discrete elements that are the building blocks of solar magnetism and with regard to the larger-scale spatial and temporal patterns in which the magnetic elements emerge and disappear. The workshop was held during November 1-5, 1993 in Soesterberg, The Netherlands. The fifty participants took a very active part in making the workshop quite a lively one. The articles in these proceedings cover most of the oral and poster presentations, excepting a dozen soon to be published elsewhere.