Modeling the Stellar Environment PDF Download

Author: P. DELACHE (Ed)
Publisher: Atlantica Séguier Frontières
ISBN: 9782863320617
Category : Astrophysics
Languages : en
Pages : 364

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Author: Institut d'astrophysique (Paris, France)
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: International Astronomical Union. Symposium
Publisher: Cambridge University Press
ISBN: 9780521889834
Category : Science
Languages : en
Pages : 506

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Stellar models are the very basic building blocks with which we build up our knowledge of the Universe. New numerical experiments are heralding a new level of sophistication in our ability to model, and understand, how stars work. This volume provides an overview and the most recent advances in modeling of stellar structure and evolution. Modeling of stars relies on our understanding of the detailed physical processes happening in stars, and the most recent observations of stars made by modern large telescopes and current high technologies. IAU Symposium 252 presents the most recent developments in five key areas, including: improvements of the physical ingredients of stellar models; the evolution of low and intermediate mass stars; the evolution of massive stars; close binary evolution; and stellar physics in the era of very large telescopes. This overview of stellar research is at a level suitable for research astronomers and graduate students.

Author: Helmut Lammer
Publisher: Springer
ISBN: 3319097490
Category : Science
Languages : en
Pages : 321

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In this book an international group of specialists discusses studies of exoplanets subjected to extreme stellar radiation and plasma conditions. It is shown that such studies will help us to understand how terrestrial planets and their atmospheres, including the early Venus, Earth and Mars, evolved during the host star’s active early phase. The book presents an analysis of findings from Hubble Space Telescope observations of transiting exoplanets, as well as applications of advanced numerical models for characterizing the upper atmosphere structure and stellar environments of exoplanets. The authors also address detections of atoms and molecules in the atmosphere of “hot Jupiters” by NASA’s Spitzer telescope. The observational and theoretical investigations and discoveries presented are both timely and important in the context of the next generation of space telescopes. The book is divided into four main parts, grouping chapters on exoplanet host star radiation and plasma environments, exoplanet upper atmosphere and environment observations, exoplanet and stellar magnetospheres, and exoplanet observation and characterization. The book closes with an outlook on the future of this research field.

Author: Uffe G. Jorgensen
Publisher: Springer
ISBN:
Category : Science
Languages : en
Pages : 460

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This volume gives and excellent survey of our present knowledge of molecularprocesses in stellar and proto-stellar objects. It reviews molecular physicsin stellar environments and is intended to bridge the gap between astrophysicists and chemists. The topics range from the theoretical to the computational and include observational data. Among the topics treated are questions of stellar evolution, the determination of physical propertiesand structures , and the chemical composition of stellar protospheres. Opacity is studied in the context of various types of stellar and proto-stellar objects.

Author: Klaas Sjoerds de Boer
Publisher:
ISBN: 2759803562
Category : Science
Languages : en
Pages : 314

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The diverse forms that stars assume in the course of their lives can all be derived from the initial conditions: the mass and the original chemical composition. In this textbook Stars and Stellar Evolution the basic concepts of stellar structure and the main roads of stellar evolution are described. First, the observable parameters are presented, which are based on the radiation emerging from a stellar atmosphere. Then the basic physics is described, such as the physics of gases, radiation transport, and nuclear processes, followed by essential aspects of modelling the structure of stars. After a chapter on star formation, the various steps in the evolution of stars are presented. This leads us to brown dwarfs, to the way a star changes into the red-giant state and numerous other stages of evolution and ultimately to the stellar ashes such as white dwarfs, supernovae and neutron stars. Stellar winds, stellar rotation and convection all in uence the way a star evolves. The evolution of binary stars is included by using several canonical examples in which interactive processes lead to X-ray binaries and supernovae of type Ia. Finally, the consequences of the study of stellar evolution are tied to observed mass and luminosity functions and to the overall evolution of matter in the universe. The authors aim at reaching an understanding of stars and their evolution by both graduate students and astronomers who are not themselves investigating stars. To that end, numerous graphs and sketches, among which the Hertzsprung-Russell diagram is the dominant one, help trace the ways of stellar evolution. Ample references to specialised review articles as well as to relevant research papers are included.

Author: Lynn Buchele
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 64

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Accurate stellar modeling requires using our understanding of phenomena far smaller than humans can observe to study some of the largest objects in the universe. One quantity that bridges this gap is the mean opacity, which uses knowledge about atomic and molecular interactions with light to inform how photons carry energy through a star. As the mean opacity depends on both the quantum mechanics of atoms and molecules and the macroscopic properties of the star (temperature, density, composition) it can be tricky to calculate. Traditionally, stellar modeling programs avoid the time-consuming computation of opacity by interpolating off of pre-made opacity tables. However, this interpolation introduces the possibility of error. In low-temperature areas of a star (less than 10,000K), this error is likely to be largest when the composition of the star differs from the composition used to create the tables. One way to examine this error is to model stars using low-temperature opacity values calculated on-the-fly. In this case, on-the-fly means using opacity calculated as the star is being modeled by a low-temperature opacity code using the exact temperature, density, and composition of each region within the star. This work describes the process of adapting the Atlas Opacity Program (ATOP) for use as an on-the-fly opacity code and discusses the results of using on-the-fly opacity values for several stellar evolution models created with the Modules for Experiments in Stellar Astrophysics (MESA) code. These models show that the effect of using on-the-fly opacity is more pronounced in models where the relative abundance of carbon to oxygen in the outer layers of the star changes significantly over the course of the star’s evolution.

Author: Kevin Marvel
Publisher: Universal-Publishers
ISBN: 1581120613
Category : Nature
Languages : en
Pages : 526

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The dissertation presents the results of a multi-epoch very long baseline interferometric study of water masers located in the extended atmospheres of evolved stars. The research was performed using the Very Long Baseline Array and Very Large Array of the National Radio Astronomy Observatory. Optical monitoring of the stars was provided by the American Association of Variable Star Observers, the Variable Star Network and Dr. Bill Neely of the NF/Observatory. Water masers of found to exist in a region where a population inversion of the rotation transition of 22 GHz can be maintained by collisional pumping. The masers are identified as individual pockets of gas, which have the good velocity coherence and may be imaged using radio interferometry. Stellar winds are initiated in these sources by dust formation and acceleration of the gas through momentum coupling. The typical wind speeds in the region of the water masers are 10 to 20 km/s The water masers are followed through several epochs of observation and exhibit proper motions consistent with the assumed source distance and the measured outflow of velocity in the water maser region. Estimates of the distance to the sources using statistical approximation are in agreement with the currently accepted distances to the stars. A detailed kinematic model is used to describe the flow motions of the gas in the maser region. The regions are found to be complex and not well modeled by uniform radial outflow, radial outflow with rotation, or radial with acceleration. The reasons for this are explored and include anisotropic velocity fields induced through non-uniform dust formations near the star and incomplete sampling of the outflow due to a lack of detected masers. Possibilities for future work in the subject are described and include more sophisticated modeling, more sensitive observations, and analysis of other maser species.

Author: National Research Council
Publisher: National Academies Press
ISBN: 0309157994
Category : Science
Languages : en
Pages : 324

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Driven by discoveries, and enabled by leaps in technology and imagination, our understanding of the universe has changed dramatically during the course of the last few decades. The fields of astronomy and astrophysics are making new connections to physics, chemistry, biology, and computer science. Based on a broad and comprehensive survey of scientific opportunities, infrastructure, and organization in a national and international context, New Worlds, New Horizons in Astronomy and Astrophysics outlines a plan for ground- and space- based astronomy and astrophysics for the decade of the 2010's. Realizing these scientific opportunities is contingent upon maintaining and strengthening the foundations of the research enterprise including technological development, theory, computation and data handling, laboratory experiments, and human resources. New Worlds, New Horizons in Astronomy and Astrophysics proposes enhancing innovative but moderate-cost programs in space and on the ground that will enable the community to respond rapidly and flexibly to new scientific discoveries. The book recommends beginning construction on survey telescopes in space and on the ground to investigate the nature of dark energy, as well as the next generation of large ground-based giant optical telescopes and a new class of space-based gravitational observatory to observe the merging of distant black holes and precisely test theories of gravity. New Worlds, New Horizons in Astronomy and Astrophysics recommends a balanced and executable program that will support research surrounding the most profound questions about the cosmos. The discoveries ahead will facilitate the search for habitable planets, shed light on dark energy and dark matter, and aid our understanding of the history of the universe and how the earliest stars and galaxies formed. The book is a useful resource for agencies supporting the field of astronomy and astrophysics, the Congressional committees with jurisdiction over those agencies, the scientific community, and the public.

Author: Rudolf Kippenhahn
Publisher: Springer Science & Business Media
ISBN: 3642615236
Category : Science
Languages : en
Pages : 480

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A complete and comprehensive treatment of the physics of the stellar interior and the underlying fundamental processes and parameters. The text presents an overview of the models developed to explain the stability, dynamics and evolution of the stars, and great care is taken to detail the various stages in a star's life. The authors have succeeded in producing a unique text based on their own pioneering work in stellar modeling. Since its publication, this textbook has come to be considered a classic by both readers and teachers in astrophysics. This study edition is intended for students in astronomy and physics alike.