The Solar Activity Cycle


Book Description

A collection of papers edited by four experts in the field, this book sets out to describe the way solar activity is manifested in observations of the solar interior, the photosphere, the chromosphere, the corona and the heliosphere. The 11-year solar activity cycle, more generally known as the sunspot cycle, is a fundamental property of the Sun. This phenomenon is the generation and evolution of magnetic fields in the Sun’s convection zone, the photosphere. It is only by the careful enumeration and description of the phenomena and their variations that one can clarify their interdependences. The sunspot cycle has been tracked back about four centuries, and it has been recognized that to make this data set a really useful tool in understanding how the activity cycle works and how it can be predicted, a very careful and detailed effort is needed to generate sunspot numbers. This book deals with this topic, together with several others that present related phenomena that all indicate the physical processes that take place in the Sun and its exterior environment. The reviews in the book also present the latest theoretical and modelling studies that attempt to explain the activity cycle. It remains true, as has been shown in the unexpected characteristics of the first two solar cycles in the 21st century, that predictability remains a serious challenge. Nevertheless, the highly expert and detailed reviews in this book, using the very best solar observations from both ground- and space based telescopes, provide the best possible report on what is known and what is yet to be discovered. Originally published in Space Science Reviews, Vol 186, Issues 1-4, 2014.




Solar and Space Physics


Book Description

In 2010, NASA and the National Science Foundation asked the National Research Council to assemble a committee of experts to develop an integrated national strategy that would guide agency investments in solar and space physics for the years 2013-2022. That strategy, the result of nearly 2 years of effort by the survey committee, which worked with more than 100 scientists and engineers on eight supporting study panels, is presented in the 2013 publication, Solar and Space Physics: A Science for a Technological Society. This booklet, designed to be accessible to a broader audience of policymakers and the interested public, summarizes the content of that report.




Solar Image Analysis and Visualization


Book Description

The SECCHI A and B instrument suites (Howard et al. , 2006) onboard the two STEREO mission spacecraft (Kaiser, 2005) are each composed of: one Extreme Ultra-Violet Imager (EUVI), two white-light coronagraphs (COR1 and COR2), and two wide-angle heliospheric imagers (HI1 and HI2). Technical descriptions of EUVI, COR1 and the HIs can be found in Wuelser et al. (2004), Thompson et al. (2003), and De?se et al. (2003), respectively. The images produced by SECCHI represent a data visualization challenge: i) the images are 2048×2048 pixels (except for the HIs, which are usually binned onboard 2×2), thus the vast majority of computer displays are not able to display them at full frame and full r- olution, and ii) more importantly, the ?ve instruments of SECCHI A and B were designed to be able to track Coronal Mass Ejections from their onset (with EUVI) to their pro- gation in the heliosphere (with the HIs), which implies that a set of SECCHI images that covers the propagation of a CME from its initiation site to the Earth is composed of im- ?1 ages with very different spatial resolutions – from 1. 7 arcsecondspixel for EUVI to 2. 15 ?1 arcminutespixel for HI2, i. e. 75 times larger. A similar situation exists with the angular scales of the physical objects, since the size of a CME varies by orders of magnitude as it expands in the heliosphere.




A study of quiescent prominences using SDO and STEREO data


Book Description

In this dissertation, the structure, dynamics and evolution of two quiescent prominences were studied. Quiescent prominences are large structures and mainly associated with the quiet Sun region. For the analysis, the high spatial and temporal cadence data from the Solar Dynamic Observatory (SDO), and the Solar Terrestrial Relations Observatory (STEREO) were used. The observations from two different directions were combined and the prominence in 3D were studied. In the study of polar crown prominence, the prominence flows on limb were mainly investigated and its association with on-disk brightenings were found. The merging of diffused active region flux in the already formed chain of prominence caused the several brightenings in the filament channel and also injected the plasma upward with an average velocity of 15 km/s. In another study, the triggering mechanism of a quiescent tornado-like prominence was investigated. Flares from the neighboring active region triggered the tornado-like motions on the top of the prominence. Active region field contracts after the flare which results in the expansion of prominence cavity. The prominence helical magnetic field expands and plasma moves along the field lines which appear as a tornado-like activity. These observational investigations led to the understanding of structure and dynamics of quiescent prominences, which could be useful for theoretical prominence models.







Solar Prominences


Book Description

This volume presents the latest research results on solar prominences, including new developments on e.g. chirality, fine structure, magnetism, diagnostic tools and relevant solar plasma physics. In 1875 solar prominences, as seen out of the solar limb, were described by P.A. Secchi in his book Le Soleil as "gigantic pink or peach-flower coloured flames". The development of spectroscopy, coronagraphy and polarimetry brought tremendous observational advances in the twentieth century. The authors present and discuss exciting new challenges (resulting from observations made by space and ground-based telescopes in the 1990s and the first decade of the 21st century) concerning the diagnostics of prominences, their formation, their life time and their eruption along with their impact in the heliosphere (including the Earth). The book starts with a general introduction of the prominence “object” with some historical background on observations and instrumentation. In the next chapter, the various forms of prominences are described with a thorough attempt of classification. Their thermodynamic (and velocity) properties are then derived with emphasis on the methods (and their limits) used. This goes from the simplest optically thin case to the heavy radiative treatment of plasmas out of local thermodynamic equilibrium. The following chapters are devoted to the magnetic field measurements and indirect derivation. A new branch of diagnostic tools, the seismology, is presented along with some MHD basics. This allows to better understand the propagation of waves, the energy and force equilibria. Both small-scale and large-scale studies and their relationship are presented. The importance of the newly discovered cavities is stressed in the context of prominence destabilization. The issues of prominence formation and eruption, their connection with flares and Coronal Mass Ejections and their impact on the Earth are addressed on the basis of the latest results. Finally, an exciting new area of research is unveiled with the newly discovered evidence of similar manifestations in the Universe and their possible impact on the habitability of exoplanets. References to the basic physics (where necessary) are provided and the proposed web sites addresses will allow the reader to load exciting movies. The book is aimed at advanced students in astrophysics, post-graduates, solar physicists and more generally astrophysicists. Amateurs will enjoy the many new images which go with the text.




Multi-Wavelength Investigations of Solar Activity (IAU S223)


Book Description

These Proceedings present the most recent results from the highly successful international solar space missions (SOHO, CORONAS-F, TRACE, RHESSI, YOHKOH) and ground observatories around the Earth, reported at the IAU Symposium 223 held in St. Petersburg, Russia, June 14-19, 2004. These include discussions of the current theories of solar dynamics and activity, new constraints provided by the multi-wavelength observations of the Sun from the interior to the heliosphere, as well as discussions of future coordinated plans and efforts of multi-wavelength investigations of the Sun. The Proceedings contain the material of seven plenary sessions and three round-table discussions




Solar activity reports


Book Description