Download or read book On Accretion by Compact Objects from a Stellar Wind written by Mario Livio and published by . This book was released on 1990 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Physics of Accretion Onto Compact Objects written by Keith O. Mason and published by Springer. This book was released on 1986 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wind Accretion Onto Compact Objects written by Ileyk El Mellah and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: X-ray emission associated to accretion onto compact objects displays important levels of photometric and spectroscopic time-variability. When the accretor orbits a Supergiant star, it captures a fraction of the supersonic radiatively-driven wind which forms shocks in its vicinity. The amplitude and stability of this gravitational beaming of the flow conditions the mass accretion rate responsible, in fine, for the X-ray luminosity of those Supergiant X-ray Binaries (SgXB). The capacity of this low angular momentum inflow to form a disc susceptible to be the stage of instabilities remains at stake.Using state-of-the-art numerical setups, we characterize the structure of a Bondi-Hoyle- Lyttleton flow onto a compact object, from the shock down to the vicinity of the accretor, typically five orders of magnitude smaller. The evolution of the bow shock which forms around the accretor (transverse structure, opening angle, stability, temperature profile...) with the Mach number of the flow is detailed. The robustness of those simulations based on the High Performance Computing MPI-AMRVAC code is supported by the topology of the inner sonic surface, consistent with theoretical expectations.We develop a synthetic model of mass transfer in SgXB which couples the launching of the wind the stellar parameters, the orbital evolution of the streamlines and the accretion process. We show that the shape of the permanent flow is entirely determined by the filling and Eddington factor, the mass ratio and the alpha force multiplier. Provided scales are known, we can trace back, eg, the X-ray luminosity, the accretion mechanism (stream or wind-dominated) and the shearing of the inflow.
Download or read book Numerical Studies of Gravitational Accretion from X Ray Heated Stellar Winds written by James Anthony Lupo and published by . This book was released on 1981 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present three numerical models of accretion from radiation driven stellar winds onto compact objects in massive X-ray binary systems. The wind is given a velocity profile consistent with a radiatively driven wind, and a 'negative mass' gravitational potential is derived from this profile to represent the wind driving force in the hydrodynamic equations. An X-ray heating model is used which determines the X-ray heating time from the Compton heating time and the known steady state energies for optically thin gas illuminated by X-rays. This allows X-ray heating to be included in the hydrodynamic equations. The X-ray luminosity is held proportional to the accretion rate, assuming that the gravitational potential energy released is equivalent to 10% of the infalling rest-mass energy. A two-dimensional Eulerian computer code is used to solve the equations of motion. Model estimates of the ionization structure, accretion rates and flow characteristics, and the effects of thermal instabilities are discussed. The impact of the X-ray radiation on the wind driving force is demonstrated. Results indicate a possible mechanism for slow X-ray flares, such as observed in 4U1700-37.
Download or read book Literature 1991 Part 2 written by Astronomisches Rechen-Institut and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 1592 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Astronomy and Astrophysics Abstracts" appearing twice a year has become oneof the fundamental publications in the fields of astronomy, astrophysics andneighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. The abstrats 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.
Download or read book MHD Flows in Compact Astrophysical Objects written by Vasily S. Beskin and published by Springer Science & Business Media. This book was released on 2009-12-08 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accretion flows, winds and jets of compact astrophysical objects and stars are generally described within the framework of hydrodynamical and magnetohydrodynamical (MHD) flows. Analytical analysis of the problem provides profound physical insights, which are essential for interpreting and understanding the results of numerical simulations. Providing such a physical understanding of MHD Flows in Compact Astrophysical Objects is the main goal of this book, which is an updated translation of a successful Russian graduate textbook. The book provides the first detailed introduction into the method of the Grad-Shafranov equation, describing analytically the very broad class of hydrodynamical and MHD flows. It starts with the classical examples of hydrodynamical accretion onto relativistic and nonrelativistic objects. The force-free limit of the Grad-Shafranov equation allows us to analyze in detail the physics of the magnetospheres of radio pulsars and black holes, including the Blandford-Znajek process of energy extraction from a rotating black hole immersed in an external magnetic field. Finally, on the basis of the full MHD version of the Grad-Shafranov equation the author discusses the problems of jet collimation and particle acceleration in Active Galactic Nuclei, radio pulsars, and Young Stellar Objects. The comparison of the analytical results with numerical simulations demonstrates their good agreement. Assuming that the reader is familiar with the basic physical and mathematical concepts of General Relativity, the author uses the 3+1 split approach which allows the formulation of all results in terms of physically clear language of three dimensional vectors. The book contains detailed derivations of equations, numerous exercises, and an extensive bibliography. It therefore serves as both an introductory text for graduate students and a valuable reference work for researchers in the field.
Download or read book Cool Discs Hot Flows written by Magnus Axelsson and published by American Institute of Physics. This book was released on 2008-10-16 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: All papers have been peer-reviewed. These proceedings contain research papers from the participants of the astrophysics conference “Cool discs, hot flows”. The main focus of the conference was on physical processes of accreting compact objects. Topics covered include wind-fed accretion, neutron stars and white dwarfs, ultraluminous X-ray sources and temporal variability.
Download or read book Interacting Binaries written by S.N. Shore and published by Springer Science & Business Media. This book was released on 2006-01-27 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observational and Theoretical Issues of Interacting Binaries was the topic of the 22nd Advanced Course of the Swiss Society for Astrophysics and Astronomy. It was the first time that binary systems were the center of attention of our course. The established concept and organisation of the Advanced Course has been retained: three scientists, all acknowledged experts in their respective fields, were each invited to give nine one-hour lectures within the period of a week. The Advanced Course took place from April 6 to 11, 1992, at Les Diablerets, a charming resort in the Swiss alps. The high level of the lectures, the international background of the 65 participants, including many young students, and the beauty of the surroundings all contributed to the success of the course. The lecture notes of this course, the 22nd in our series, are also the third to be published by Springer-Verlag. Well over half of all stars seem to exist in binary systems. The study of binary evolution is therefore essential for our understanding of stellar evolution in general. The evolution of interacting binaries contains in itself many of the problems met in other fields of modern astrophysics. This is very apparent in these lecture notes.
Download or read book The Physics of Wind Fed Accretion written by and published by . This book was released on 2008 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: We provide a brief review of the physical processes behind the radiative driving of the winds of OB stars and the Bondi-Hoyle-Lyttleton capture and accretion of a fraction of the stellar wind by a compact object, typically a neutron star, in detached high-mass X-ray binaries (HMXBs). In addition, we describe a program to develop global models of the radiatively-driven photoionized winds and accretion flows of HMXBs, with particular attention to the prototypical system Vela X-1. The models combine XSTAR photoionization calculations, HULLAC emission models appropriate to X-ray photoionized plasmas, improved models of the radiative driving of photoionized winds, FLASH time-dependent adaptive-mesh hydrodynamics calculations, and Monte Carlo radiation transport. We present two- and three-dimensional maps of the density, temperature, velocity, ionization parameter, and emissivity distributions of representative X-ray emission lines, as well as synthetic global Monte Carlo X-ray spectra. Such models help to better constrain the properties of the winds of HMXBs, which bear on such fundamental questions as the long-term evolution of these binaries and the chemical enrichment of the interstellar medium.
Download or read book Literature 1992 Part 1 written by Astronomisches Recheninstitut and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1456 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Astronomy and Astrophysics Abstracts" appearing twice a year has become oneof the fundamental publications in the fields of astronomy, astrophysics andneighbouring 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.
Download or read book Disc Winds Matter written by James Matthews and published by Springer. This book was released on 2017-08-01 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the application of a Monte Carlo radiative transfer code to accretion disc winds in two types of systems spanning 9 orders of magnitude in mass and size. In both cases, the results provide important new insights. On small scales, the presence of disc winds in accreting white dwarf binary systems has long been inferred from the presence of ultraviolet absorption lines. Here, the thesis shows that the same winds can also produce optical emission lines and a recombination continuum. On large scales, the thesis constructs a simple model of disc winds in quasars that is capable of explaining both the observed absorption and emission signatures – a crucial advance that supports a disc-wind based unification scenario for quasars. Lastly, the thesis also includes a theoretical investigation into the equivalent width distribution of the emission lines in quasars, which reveals a major challenge to all unification scenarios.
Download or read book Evolutionary Processes in Interacting Binary Stars written by Y. Kondo and published by Springer Science & Business Media. This book was released on 1992-06-30 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the proceedings of IAU Symposium No. 151 `Evolutionary Processes in Interacting Binary Stars,' which was held from 5 to 9 August 1991 in Cordóba, Argentina. The primary aim of this conference was to review and evaluate our current understanding of the evolutionary processes in wide variety of interacting binary stars from their births to their deaths. Subjects included the formation of binaries, mass flow and transfer, accretion processes, and binaries with collapsed components, such as novae, X-ray binaries and binary pulsars. As the field covered is both broad and diverse, there were in all thirty-seven invited talks; sixty-two contributed papers were also presented. In addition, these proceedings contain comments from a panel discussion of the major unsolved problems of interacting binary stars.
Download or read book Introduction to Advanced Astrophysics written by V. Kourganoff and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this textbook is to provide a basic knowledge of the main parts of modern astrophysics for all those starting their studies in this field at the undergraduate level. The reader is supposed to have only a high school training in physics and mathematics. In many respects this Introduction to Advanced Astrophysics could represent a volume of the Berkeley Physics Course. Thus, the primary audience for this work is composed of students in astronomy, physics, mathematics, physical chemistry and engineering. It also includes high school teachers of physics and mathematics. Many amateur astronomers will fmd it quite accessible. In the frame of approximations proper to an introductory textbook, the treatment is quite rigorous. Therefore, it is also expected to provide a firm background for a study of advanced astrophysics on a postgraduate level. A rather severe selection is made here among various aspects of the Universe accessible to modern astronomy. This allows us to go beyond simple information on astronomical phenomena - to be found in popular books - and to insist upon explanations based on modern general physical theories. More precisely, our selection of topics is determined by the following considerations: The study of the solar system (the Moon and the planets) has recently progressed at a tremendous rate. However, the very rich harvest of observations provided by space research is mainly purely descriptive and is perfectly presented in review papers of Scien tific American, Science, Physics Today and similar magazines.
Download or read book Exploring the X Ray Universe written by Philip A. Charles and published by CUP Archive. This book was released on 1995-10-12 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: The one-stop general book on the whole of X-ray astronomy.
Download or read book Literature 1987 Part 1 written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy and Astrophysics Abstracts aims to present a comprehensive documen tation of the literature concerning all aspects of astronomy, astrophysics, and their border fields. It is devoted to the recording, summarizing, and indexing of the relevant publications throughout the world. Astronomy and Astrophysics Abstracts is prepared by a special department of the Astronomisches Rechen-Institut under the auspices of the International Astronomical Union. Volume 43 records literature published in 1987 and received before August 15, 1987. Some older documents which we received late and which are not surveyed in earlier volumes are included too. We acknowledge with thanks contributions of our colleagues all over the world. We also express our gratitude to all organiza tions, observatories, and publishers which provide us with complimentary copies of their publications. Starting with Volume 33, all the recording, correction, and data processing work was done by means of computers. The recording was done by our technical staff members Ms. Helga Ballmann, Ms. Beate Gobel, Ms. Monika Kohl, Ms. Sylvia Matyssek, Ms. Doris Schmitz-Braunstein, Ms. Utta-Barbara Stegemann. Mr. Jochen Heidt and Mr. Kristopher Polzine supported our task by careful proof reading. It is a pleasure to thank them all for their encouragement. Heidelberg, October 1987 The Editors Contents Introduction . . . . . . . . . . . 1 Concordance Relation: PHYS-AAA 3 Abbreviations 5 Periodicals, Proceedings, Books, Activities 001 Periodicals . . . . . . . . . . . 10 002 Bibliographical Publications, Documentation, Catalogues, Data Bases 50 003 Books ...... .
Download or read book Nonlinear Gravitodynamics The Lense thirring Effect written by Remo Ruffini and published by World Scientific. This book was released on 2003-05-08 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a detailed, up-to-date account of the Lense-Thirring effect and its implications for physics and astrophysics. Starting from a profound intuition of Lense and Thirring in 1918, based on a simple solution to the linearized Einstein field equations, this has emerged in the past four decades as a phenomenon of extraordinary importance in cosmology, radio jets in quasars, and the physics of neutron stars and black holes, besides leading to some of the most sophisticated experiments ever performed in the space surrounding our planet. The book contains the contributions presented at the “Third William Fairbank Meeting”, which have been expanded by adding a complete set of classical and prominent contemporary papers on this subject and a general introduction by R Ruffini.
Download or read book Stars and Stellar Processes written by Mike Guidry and published by Cambridge University Press. This book was released on 2019-02-07 with total page 573 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook offers a modern approach to the physics of stars, assuming only undergraduate-level preparation in mathematics and physics, and minimal prior knowledge of astronomy. It starts with a concise review of introductory concepts in astronomy, before covering the nuclear processes and energy transport in stellar interiors, and stellar evolution from star formation to the common stellar endpoints as white dwarfs and neutron stars. In addition to the standard material, the author also discusses more contemporary topics that students will find engaging, such as neutrino oscillations and the MSW resonance, supernovae, gamma-ray bursts, advanced nucleosynthesis, neutron stars, black holes, cosmology, and gravitational waves. With hundreds of worked examples, explanatory boxes, and problems with solutions, this textbook provides a solid foundation for learning either in a classroom setting or through self-study.
