Juhan Frank – författare

Accretion Power in Astrophysics examines accretion as a source of energy in both binary star systems containing compact objects, and in active galactic nuclei. Assuming a basic knowledge of physics, the authors describe the physical processes at work in accretion discs and other accretion flows. The first three chapters explain why accretion is a source of energy, and then present the gas dynamics and plasma concepts necessary for astrophysical applications. The next three chapters then develop accretion in stellar systems, including accretion onto compact objects. Further chapters give extensive treatment of accretion in active galactic nuclei, and describe thick accretion discs. A new chapter discusses recently discovered accretion flow solutions. The third edition is greatly expanded and thoroughly updated. New material includes a detailed treatment of disc instabilities, irradiated discs, disc warping, and general accretion flows. The treatment is suitable for advanced undergraduates, graduate students and researchers.

Accretion disks in astrophysics represent the characteristic flow by which compact bodies accrete mass from their environment. Their intrinsically high luminosity, and recent progress in observational accessibility at all wavelength bands, have led to rapidly growing awareness of their importance and made them the object of intense research on widely different scales, ranging from binary stars to young stellar objects and active galactic nuclei. This book contains the proceedings of the NATO Advanced Workshop for which some of the most active researchers in the different fields came together at the Max-Planck-Institut for Astrophysics in Garching in March, 1993. Its reviews and contributions give an up-to-date account of the present status of our understanding and provide a stimulating challenge in discussions of open questions in a rapidly developing field.

With the advent of space observatories and modern developments in ground­ based astronomy and concurrent progress in the theoretical understanding of these observations it has become clear that accretion of material on to compact objects is an ubiquitous mechanism powering very diverse astrophysical sources ranging in size and luminosity by many orders of magnitude. A problem common to these systems is that the material accreted must in general get rid of its angular momentum and this leads to the formation of an Accretion Disk which allows angular momentum re-distribution and converts potential energy into radiation with an efficiency which can be higher than the nuclear burning yield. These systems range in size from quasars and active galactic nuclei to accretion disks around forming stars and the early solar system and to compact binaries such as cataclysmic variables and low-mass X-ray binaries. Other objects that should be mentioned in this context are 88433, the black hole binary candidates, and possibly gamma-ray burst sources. Observations of these systems have provided important constraints for theoretical accretion disk models on widely differing scales, lumi­ nosities, mass-transfer rates and physical environments.

Accretion disks in astrophysics represent the characteristic flow by which compact bodies accrete mass from their environment. Their intrinsically high luminosity, and recent progress in observational accessibility at all wavelength bands, have led to rapidly growing awareness of their importance and made them the object of intense research on widely different scales, ranging from binary stars to young stellar objects and active galactic nuclei. This book contains the proceedings of the NATO Advanced Workshop on `Theory of Accretion Disks 2' for which some of the most active researchers in the different fields came together at the Max-Planck-Institut for Astrophysics in Garching in March, 1993. Its reviews and contributions give an up-to-date account of the present status of our understanding and provide a stimulating challenge in discussions of open questions in a rapidly developing field.

With the advent of space observatories and modern developments in ground­ based astronomy and concurrent progress in the theoretical understanding of these observations it has become clear that accretion of material on to compact objects is an ubiquitous mechanism powering very diverse astrophysical sources ranging in size and luminosity by many orders of magnitude. A problem common to these systems is that the material accreted must in general get rid of its angular momentum and this leads to the formation of an Accretion Disk which allows angular momentum re-distribution and converts potential energy into radiation with an efficiency which can be higher than the nuclear burning yield. These systems range in size from quasars and active galactic nuclei to accretion disks around forming stars and the early solar system and to compact binaries such as cataclysmic variables and low-mass X-ray binaries. Other objects that should be mentioned in this context are 88433, the black hole binary candidates, and possibly gamma-ray burst sources. Observations of these systems have provided important constraints for theoretical accretion disk models on widely differing scales, lumi­ nosities, mass-transfer rates and physical environments.