Solar Atmospheric Oscillations

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

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SCORe ’96: Solar Convection and Oscillations and their Relationship

SCORe ’96: Solar Convection and Oscillations and their Relationship
Author: F.P. Pijpers
Publisher: Springer Science & Business Media
Total Pages: 384
Release: 1998-01-31
Genre: Science
ISBN: 9780792348528

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This volume contains the reviews and poster papers presented at the workshop Solar Convection and Oscillations and their Relationship: SCORe '96, held in Arhus, Denmark, May 27 - 31, 1996. The aim of this workshop was to bring together experts in the fields of convection and helioseismology, and to stimulate collaborations and joint research. The participation to this workshop was purposely kept limited in order to provide optimal conditions for informal discussions. In autumn of 199,5 the long-awaited GONG network of solar telescopes became fully operational and the first data already show significant improvement over existing datasets on solar oscillations. Furthermore, in December of 1995 the satellite SOHO was launched which, together with GONG, provides a major step forward in both the quantity and the quality of available solar oscillation data. It is with this in mind that we decided to organize the workshop to prepare for the optimal use of this wealth of data, with which to deepen our understanding of solar structure and specifically, of one of the longest-standing problems in solar and stellar modelling: the treatment of convection.

Solar Interior and Atmosphere

Solar Interior and Atmosphere
Author: Arthur N. Cox
Publisher: University of Arizona Press
Total Pages: 1444
Release: 1991-12
Genre: Science
ISBN: 9780816512294

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Observational data derived from the world's largest solar telescopes are correlated with theoretical discussions in nuclear and atomic physics by contributors representing a wide range of interests in solar research.

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).

Problems of Solar and Stellar Oscillations

Problems of Solar and Stellar Oscillations
Author: D.O. Gough
Publisher: Springer Science & Business Media
Total Pages: 480
Release: 2012-12-06
Genre: Science
ISBN: 9400970889

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D. O. GOUGH Institute of Astronomy. Madingley Road. Cambridge. U. K. IAU Colloquium 66 on 'Problems of Solar and Stellar Oscillations' was held at the Crimean Astrophysical Observatory, U. S. S. R. , on 1-5 September, 1981. The principal purpose of the colloquium was to study the low-amplitude oscillations of the Sun and, to a lesser extent, to consider similar oscillations of other stars. Much of the emphasis of the discussions was on the diagnostic value of the oscilla tions. In the last few years we have become aware that the frequencies of the five-minute modes of high degree, which constitute the major component of the oscillations discovered twenty years ago by Evans and Michaud, can be used to put quite tight bounds on the stratification of the solar convection zone. These permit a calibration of solar models computed from so-called standard evolution theory. Modes of low degree penetrate beneath the convection zone to the core of the Sun, and can in principle test the evolution theory. Therefore there was considerable interest in the reports of the latest observations of such modes. Broadly speaking, those observations confirm the cali bration by the high-degree modes, but there remain some systematic discrepancies that demand some revision of the theory. Besides the gross aspects of evolution theory, there are also more intricate details to be understood.

The Sun, Solar Analogs and the Climate

The Sun, Solar Analogs and the Climate
Author: Joanna Dorothy Haigh
Publisher: Springer Science & Business Media
Total Pages: 436
Release: 2006-03-30
Genre: Science
ISBN: 354027510X

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The 34th Saas-Fee advanced course of the Swiss Society of Astronomy and Astrophysics (SSAA) took place from March 15 to 20, 2004, in Davos, on the subject of The Sun, Solar Analogs and the Climate. PresentlytheSwissmountainresortofDavosisprobablymostwellknown for hosting an event on globalization. However, it is because Davos also happens to be the seat of the Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center, that this course on a “global” subject was hosted here. Exceptionally, the topic of this course was not purely astrophysical, but themembersoftheSSAAdecidedtosupportitallthesameduetothetimely topic of global warming and its possible link to solar variations. In these times of concern about global warming, it is important to und- stand solar variability and its interaction with the atmosphere. Only in this way can we distinguish between the solar and anthropogenic contributions to the rising temperatures. Therefore, this course addressed the observed va- ability of the Sun and the present understanding of the variability’s origin and its impact on the Earth’s climate. Comparing the solar variability with that of solar analog stars leads to a better understanding of the solar activity cycle and magnetic activity in general, and helps us to estimate how large the solar variations could be on longer time scales. Inspiteofthefantasticweatherandsnowconditionswhichreignedduring this week, the participants assiduously took part in the lectures. This is proof ofthehighqualityofthelecturesthatthethreespeakers,JoannaHaigh,Mike Lockwood and David Soderblom, delivered. We deeply thank them for their contributions and e?orts and hope that the readers will enjoy the book as much as we enjoyed their lectures.

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.