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Sunquakes


Sunquakes
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Sunquakes


Sunquakes
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Author : J. B. Zirker
language : en
Publisher: JHU Press
Release Date : 2003-10-29

Sunquakes written by J. B. Zirker and has been published by JHU Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003-10-29 with Science categories.


One of the most recent and exciting branches of astronomy, helioseismology—like its terrestrial counterpart—studies why the surface of the sun vibrates like a bell. Over the past three decades astronomers have gained spectacular insights into the structure and composition of the sun's interior, transforming the way we understand stellar matter. In Sunquakes, Jack B. Zirker tells the story of this new science and explains the physics behind these illuminating vibrations. Zirker recounts the discovery of solar oscillations in the early 1960s and international efforts throughout the rest of the decade to explain this phenomenon. By the mid-1970s, scientists working independently in France, Germany, Japan, and the U.S. had developed a new theoretical model of the sun that postulated the existence of trapped sound and gravity waves as the cause for the roiling of the sun's surface. Using solar oscillation data, scientists derived for the first time the thermal and dynamic properties of the solar interior and revealed its complicated rotation patterns; even such astronomical mysteries as the deficit of solar neutrinos were solved. Describing the competition and cooperation between astronomers, particle physicists, and other theorists to the technological innovations that makes solar observation more and more precise, Sunquakes provides professionals and nonscientists alike with an absorbing and accessible guide to the field of helioseismology. The book concludes with an account of recent efforts to probe the interiors of stars far beyond our own solar system.



Sunquakes


Sunquakes
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Author : J. B. Zirker
language : en
Publisher: JHU Press
Release Date : 2003-10-29

Sunquakes written by J. B. Zirker and has been published by JHU Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003-10-29 with Science categories.


One of the most recent and exciting branches of astronomy, helioseismology—like its terrestrial counterpart—studies why the surface of the sun vibrates like a bell. Over the past three decades astronomers have gained spectacular insights into the structure and composition of the sun's interior, transforming the way we understand stellar matter. In Sunquakes, Jack B. Zirker tells the story of this new science and explains the physics behind these illuminating vibrations. Zirker recounts the discovery of solar oscillations in the early 1960s and international efforts throughout the rest of the decade to explain this phenomenon. By the mid-1970s, scientists working independently in France, Germany, Japan, and the U.S. had developed a new theoretical model of the sun that postulated the existence of trapped sound and gravity waves as the cause for the roiling of the sun's surface. Using solar oscillation data, scientists derived for the first time the thermal and dynamic properties of the solar interior and revealed its complicated rotation patterns; even such astronomical mysteries as the deficit of solar neutrinos were solved. Describing the competition and cooperation between astronomers, particle physicists, and other theorists to the technological innovations that makes solar observation more and more precise, Sunquakes provides professionals and nonscientists alike with an absorbing and accessible guide to the field of helioseismology. The book concludes with an account of recent efforts to probe the interiors of stars far beyond our own solar system.



Helioseismic Measurements Of The Sun S Meridional Circulation And Sunquakes


Helioseismic Measurements Of The Sun S Meridional Circulation And Sunquakes
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Author : Ruizhu Chen
language : en
Publisher:
Release Date : 2019

Helioseismic Measurements Of The Sun S Meridional Circulation And Sunquakes written by Ruizhu Chen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.


In this thesis, we use helioseismic methods to study two separate topics, the Sun's meridional circulation and sunquake events. The Sun's meridional circulation is a key component of solar dynamo and interior dynamics, playing an important role in transporting magnetic flux and redistributing angular momentum. A profile of the meridional circulation has long been sought, but results from previous studies were not fully consistent, due to a systematic center- to-limb (CtoL) effect in helioseismic measurements that complicates the inference of meridional circulation in the deep interior. In the first part of this thesis, we measure the Sun's meridional circulation and its temporal evolution using 8 years of SDO/HMI Doppler-velocity observations, with a new CtoL-effect-removal method that we have developed in time-distance helioseismology. The long-time-averaged meridional circulation profile is found to have a three-layer flow structure: an equatorward flow is sandwiched between two poleward flow zones above and beneath it, indicating a double-cell circulation in each hemisphere. Moreover, the 3-layer flow pattern is more significant when the Sun's magnetic activity level is low, while significant changes are found in the flow structure during the active phase of the solar cycle. Besides, we also study the observational properties of the CtoL effect in the measured travel time of helioseismic waves. The CtoL effect is found isotropic relative to the azimuthal angle around the solar disk center. It also exhibits a significant frequency dependence -- it reverses sign at a frequency around 5.4 mHz, and is strongest at around 4.0 mHz. The tendency of frequency dependence varies with disk-centric distance but not with the waves' travel distance. In the second part this thesis, we focus on sunquakes. Sunquakes are helioseismic power enhancements initiated by solar flares, but not all flares generate sunquakes. It is curious why some flares cause sunquakes while others do not. Here we propose a hypothesis to explain the disproportionate occurrence of sunquakes: during a flare's impulsive phase when the flare's impact acts upon the photosphere, a sunquake tends to occur if the background oscillation at the flare's footpoint happens to oscillate downward, in the same direction with the impulse from above. To verify this hypothesis, we survey 60 strong flares in Solar Cycle 24 to search for sunquakes, by reconstructing the oscillatory velocity in the flare sites using a helioseismic holography method. A total of 24 flares are found to be sunquake active, giving a total of 41 sunquakes. It is found that in 3 − 5 mHz frequency band, 25 out of 31 (81%) sun- quakes show net downward oscillatory velocities during the flares' impulsive phases, and in 5 − 7 mHz frequency band, 33 out of 38 (87%) sunquakes show net downward velocities. These results support our hypothesis that a sunquake more likely occurs when a flare impacts a photospheric area that happens to have a downward background oscillation.



Sunspots And Sunquakes


Sunspots And Sunquakes
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Author : Colin Samuel Rosenthal
language : en
Publisher:
Release Date : 1991

Sunspots And Sunquakes written by Colin Samuel Rosenthal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1991 with Helioseismology categories.




Atmospheric Responses To Flare Generated Sunquakes


Atmospheric Responses To Flare Generated Sunquakes
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Author : Seán Quinn
language : en
Publisher:
Release Date : 2021

Atmospheric Responses To Flare Generated Sunquakes written by Seán Quinn and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with categories.




Seismic Emissions From Solar Flares


Seismic Emissions From Solar Flares
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Author : Diana Ionescu
language : en
Publisher:
Release Date : 2010

Seismic Emissions From Solar Flares written by Diana Ionescu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.


The Sun is the centre and the master of our solar system. Its power gives us light and warmth and life, but its moods can be fearsome. Sunspots, solar flares, coronal mass ejections (CME) and the plethora of other complex magnetic activities that follow the 11-year rhythm of the solar cycle can mean devastation for our technologies, from satellites, to power grids, to telecommunications. Pity the unfortunate astronaut caught unprotected in space during a solar storm!Flares are the most powerful and most dangerous events on the Sun, spewing huge quantities of radiation and particles into space, often accompanied by a CME, sometimes to pummel the Earth. Only our magnetic shield, the magnetosphere, protects us. All means must be brought to bear when studying the Sun's activity, including observations in many wavelengths from terrestrial and space-borne observatories, and the relatively new science of local helioseismology for peering beneath the surface, the photosphere. Especially during the last decade, that of Solar Cycle 23, advances in theory and technology have opened the Sun's magnetic active regions to our deeper seismic gaze.Cycle 23 was closely mapped by the Solar and Heliospheric Observatory (SOHO) orbiting between the Earth and the Sun. A fascinating discovery made with SOHO is that flares high in the Sun's corona not only project their power outwards into space, but also downwards to the photosphere, where they can cause powerful sunquakes. This thesis is devoted to sunquakes: their discovery, their characteristics, and their physics. How and why are they formed, and why do many flares not excite them? How much energy is required to produce them? And how can this unique resource of a sudden localized seismic source be used to better probe the Sun's interior? In so-doing, I present the most detailed survey yet of sunquakes and their physics.Specifically, we have used the local helioseismic technique known as helioseismic holography to detect sunquakes by imaging their acoustic sources rather than their harder-to-see expanding ripples. Nearly all known sunquakes, more than a dozen, have been discovered by us in this way. This is sufficient to begin a survey to discover which types of flares excite quakes and which do not. Using a wide range of observations over several wavelengths, we explore the effects of such features as flare area, energy, height, and spectral hardness.We have also applied a 1D radiation hydrodynamics simulation code RADYN to synthesizing the mechanisms which might create quakes. Both our survey and our simulations favour ``back-warming'', whereby the low chromosphere is suddenly heated by the flare. This energy is then quickly transferred to the adjacent photosphere producing a quake.Because seismic emission from solar flares presents by far the most localized seismic sources in the solar environment, both spatially and temporally, and flares being the only seismic generators whose operation is open to direct view, this phenomenon offers an especially opportune control facility for 21st-century helioseismology.



Multi Wavelength Analysis In Flare Seismology And The Role Of Magnetic Field Dynamics In The Seismicity Of Solar Active Regions


Multi Wavelength Analysis In Flare Seismology And The Role Of Magnetic Field Dynamics In The Seismicity Of Solar Active Regions
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Author :
language : en
Publisher:
Release Date : 2009

Multi Wavelength Analysis In Flare Seismology And The Role Of Magnetic Field Dynamics In The Seismicity Of Solar Active Regions written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.


Solar flares are one of the most catastrophic and energetic processes in the solar system, converting vast amounts of magnetic energy into kinetic and thermal energies. Some flares are believed to drive seismic events on the solar surface, but in general the majority of flares are seismically inactive. They raise several questions about sunquakes and its generation: How it is possible to determine which flares may induce sunquakes? What is the role of dynamic field changes in the generation of sunquakes? Can the magnetic field be a driver of seismic waves? Notwithstanding the strong theoretical and observational progress of the last decade, these questions still remain open. Since the first discovery of a sunquake by Kosovichev and Zharkova (1998) many other works have been written about the detection of flare generated seismic waves in the Sun (Kosovichev, 2006b; Zharkova and Zharkov, 2007; Donea et al., 1999; Donea and Lindsey, 2005; Donea et al., 2006b; Besliu-Ionescu et al., 2006a; Moradi et al., 2007; Martínez-Oliveros et al., 2007, 2008c; Martínez-Oliveros and Donea, 2009). Sunquakes are defined as the observed expanding waves on the solar photosphere induced by solar flares. It is believed that sunquakes are produced by the momentum or energy transfer of high energy particles, waves and radiation from flares into the solar photosphere. The momentum induces the generation of internal waves that travel in the solar interior where they are refracted back to the surface. They are observed as close to circular photospheric ripples, detected as changes in the mean velocity amplitude of the photosphere in Dopplergrams. The work presented here starts with multifrequency observations of seismically active flares from microwaves and hard X-rays, which give us information about the electron acceleration process taking place in the solar corona, to the much lower frequencies associated with seismic waves. As the importance of particle interactions with the solar atmosphe.



Extraterrestrial Seismology


Extraterrestrial Seismology
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Author : Vincent C. H. Tong
language : en
Publisher: Cambridge University Press
Release Date : 2015-06-25

Extraterrestrial Seismology written by Vincent C. H. Tong and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-06-25 with Science categories.


Taking a transdisciplinary approach to seismology, this unique book reviews the most recent developments in planetary seismology, helioseismology, and asteroseismology.



The Sun From Space


The Sun From Space
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Author : Kenneth R. Lang
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-04-18

The Sun From Space written by Kenneth R. Lang and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-04-18 with Science categories.


A comprehensive account of solar astrophysics and how our perception and knowledge of this star have gradually changed as mankind has elucidated ever more of its mysteries. The emphasis here is on the last decade, which has seen three successful solar spacecraft missions: SOHO, Ulysses and Yohkoh. Together, these have confirmed many aspects of the solar standard model and provided new clues to the numerous open questions that remain. The author, a leading researcher in the field, writes in a clear and concise style. Known also for his famous books "Astrophysical Formulae", "Sun, Earth and Sky" and the prize-winning "Wanderers in Space", he has succeeded once again in addressing a complex scientific topic in a very approachable way.



Electron And Proton Kinetics And Dynamics In Flaring Atmospheres


Electron And Proton Kinetics And Dynamics In Flaring Atmospheres
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Author : Valentina Zharkova
language : en
Publisher: John Wiley & Sons
Release Date : 2012-06-25

Electron And Proton Kinetics And Dynamics In Flaring Atmospheres written by Valentina Zharkova and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-06-25 with Science categories.


This timely book presents new research results on high-energy particle physics related to solar flares, covering the theory and applications of the reconnection process in a clear and comprehensible way. It investigates particle kinetics and dynamics in flaring atmospheres and their diagnostics from spectral observations, while providing an analysis of the observation data and techniques and comparing various models. Written by an internationally acclaimed expert, this is vital reading for all solar, astro-, and plasma physicists working in the field.