Physics of Formation of FeII Lines Outside LTE
Physics of Formation of FeII Lines Outside LTE

Author: Roberto Viotti

Publisher: Springer Science & Business Media

Published: 2013-04-17

Total Pages: 335

ISBN-13: 9400940238

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The same kind of physics is frequently common to very different fields of Astrophysics, so experts in each of these fields have often much to learn from each others. It was therefore logical that the International Astronomical Union should sponsor a colloquium about an ion which pro duces many spectral lines that can be used as a diagnostic for many sorts of objects, and which may sometimes have a major influence on physical processes occurring in astro physical sources. The lines of singly ionized iron (FeII) are present in absorption and emission in the spectra of objects such as the Sun, cool stars, circumstellar envelopes of hot stars, novae, diffuse nebulae including the supernova remnants, and active galactic nuclei. These lines are very often formed far from LTE, and their interpretation is not easy in view of the complex Grotrian diagram for FeII, and the gaps in the knowledge of various physical parameters. In addition, the density of very strong FeII lines becomes very large in the ultraviolet, and the lines can play a major role in the line blanketing. They need therefore to be taken into account in any energy balance argument.

Literature 1988, Part 1
Literature 1988, Part 1

Author: U. Esser

Publisher: Springer Science & Business Media

Published: 2013-11-11

Total Pages: 1266

ISBN-13: 3662123649

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From the reviews: "Astronomy and Astrophysics Abstracts has appeared in semi-annual volumes since 1969 and it has already become one of the fundamental publications in the fields of astronomy, astrophysics and neighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. ...The abstracts are classified under more than a hundred subject categories, thus permitting a quick survey of the whole extended material. The AAA is a valuable and important publication for all students and scientists working in the fields of astronomy and related sciences. As such it represents a necessary ingredient of any astronomical library all over the world." Space Science Reviews#1 "Dividing the whole field plus related subjects into 108 categories, each work is numbered and most are accompanied by brief abstracts. Fairly comprehensive cross-referencing links relevant papers to more than one category, and exhaustive author and subject indices are to be found at the back, making the catalogues easy to use. The series appears to be so complete in its coverage and always less than a year out of date that I shall certainly have to make a little more space on those shelves for future volumes." The Observatory Magazine#2

Solar Photosphere: Structure, Convection, and Magnetic Fields
Solar Photosphere: Structure, Convection, and Magnetic Fields

Author: Jan Olof Stenflo

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 546

ISBN-13: 9400910614

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Solar and stellar photospheres constitute the layers most accessible to observations, forming the interface between the interior and the outside of the stars. The solar atmosphere is a rich physics laboratory, in which the whole spectrum of radiative, dynamical, and magnetic processes that tranfer energy into space can be observed. As the fundamental processes take place on very small spatial scales, we need high· resolution observations to explore them. On the other hand the small-scale processes act together to form global properties of the sun, which have their origins in the solar interior. The rapid advances in observational techniques and theoreticallllodelling over the past decade made it very timely to bring together scientists from east and west to the first lAU Symposium on this topic. The physics of the photosphere involves complicated interactions between magnetic fields, convection, waves, and radiation. During the past decade our understanding of these gener ally small-scale structures and processes has been dramatically advanced. New instrumen tations, on ground and in space, have given us new means to study the granular convection. Diagnostic methods in Stokes polarimetry have allowed us to go beyond the limitations of spatial resolution to explore the structure and dynamics of the subarcsec magnetic struc tures. Extensive numerical simulations of the interaction between convection and magnetic fields using powerful supercomputers are providing deepened physical insight. Granulation, magnetic fields, and dynamo processes are being explored in the photospheres of other stars, guided by our improved understanding of the solar photosphere.

Astrophysical Lasers
Astrophysical Lasers

Author: Vladilen Letokhov

Publisher: Oxford University Press on Demand

Published: 2009

Total Pages: 271

ISBN-13: 0199548277

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Progress in modern radio astronomy led to the discovery of space masers in the microwave range, and it became a powerful tool for studies of interstellar star-forming molecular clouds. Progress in observational astronomy, particularly with ground-based huge telescopes and the space-based Hubble Space Telescope, has led to recent discoveries of space lasers in the optical range. These operate in gas condensations in the vicinity of the mysterious star Eta Carinae (one of the most luminous and massive stars of our Galaxy). Both maser and laser effects, first demonstrated under laboratory conditions, have now been discovered to occur under natural conditions in space too. This book describes consistently the elements of laser science, astrophysical plasmas, modern astronomical observation techniques, and the fundamentals and properties of astrophysical lasers. A book with such an interdisciplinary scope has not been available to date. The book will also be useful for a wider audience interested in modern developments of the natural sciences and technology.

Solar and Stellar Granulation
Solar and Stellar Granulation

Author: R. J. Rutten

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 638

ISBN-13: 940090911X

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Robert J. Rutten Sterrekundig Instituut Utrecht, The Netherlands Why this workshop? Why this workshop? Or rather, since the real question that arose about a year ago was not whether there should be another OAC workshop, but only what it should be about: why a workshop on granulation? To answer this question I will play an unfair trick on you. I will simply present the scientific justification which I included last autumn in a grant application to NATO's Scientific Affairs Division. It lists the reasons why I thought a workshop on this particular topic and at this particular moment ought to be worthwhile. There must be something in its reasoning, because NATO has indeed agreed to co-sponsor this workshop, and because all of you have decided to spend time and effort on your contributions and to journey to this beautiful island in order to participate. But since the proof is in the pudding, I am eager to see whether indeed this workshop will be as outstanding as I have promised; in the meantime, you are entitled to know what we got you here for. The justification went as follows: "The subject 'granulation' has recently become a hot topic, at the center of much new research, observational as well as interpretational and theoretical, and both in solar physics and in stellar physics.

Solar Interior and Atmosphere
Solar Interior and Atmosphere

Author: Arthur N. Cox

Publisher: University of Arizona Press

Published: 2018-01-30

Total Pages: 1435

ISBN-13: 0816538611

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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.

The Behavior of Chemical Elements in Stars
The Behavior of Chemical Elements in Stars

Author: Carlos Jaschek

Publisher: Cambridge University Press

Published: 1995-06-08

Total Pages: 342

ISBN-13: 052141136X

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Despite more than one century of observational stellar spectroscopy, the resulting data are not available in an easily accessible format. The necessity of such basic information is greater than ever, because new wavelength regions (ultraviolet, infrared) are now accessible and because modern receivers can only analyze short stretches of spectra, so that a careful pre-selection of strategic elements is mandatory. This book presents a summary of our knowledge of the behavior of all chemical elements identified in stars, based on observations rather than on their interpretations. Whenever possible the behavior is described quantitatively, with the help of equivalent widths in different types of stars, or different ionization stages, for both absorption and emission features. It will be essential to the spectroscopist when confronted with questions like the following: . What is the behavior of europium in metallic line stars or in S-type stars? Are the neutral lines of this element visible, are they strengthened or weakened with regard to normal dwarfs? A huge amount of data has been gathered by experts in the field and presented in a way that will be invaluable to professional astrophysicists, cosmochemists and their students.