Cyclical Variability In Stellar Winds

It is well known that stellar winds are variable, and the fluctuations are often cyclical in nature. This property seems to be shared by the winds of cool and hot stars, even though their outflows are driven by fundamentally different physical mechanisms. Since very similar models have been proposed to explain the cyclical wind variations observed in a wide variety of stars, the time was ripe for astrophysicists from many different sub-disciplines to present the state of the art in a concise form. The proceedings will provide a useful, up-to-date overview of the observations, interpretation, and modelling of the time-dependent mass outflows from all sorts of stars.

The underlying astrophysical mechanisms of the objects known as asymptotic giant branch stars - the structures that occur during the dramatic period prior to a star's death - is the main theme of this text. Over the past three decades, asymptotic giant branch stars have become a topic of their own, and the contributions to this volume all focus on these entities themselves, rather than their connections to other fields of astronomy. Among the many topics covered are new methods of high- quality infrared observation and the more detailed and realistic simulations made possible by increasingly fast computers. This collection should be useful to graduate students who work in the field, teachers who want to address the subject in their courses, and to astronomers from various backgrounds who are interested in the astrophysics of AGB stars.

In a unique collaboration, Nature Publishing Group and Institute of Physics Publishing have published the most extensive and comprehensive reference work in astronomy and astrophysics. This unique resource covers the entire field of astronomy and astrophysics and this online version includes the full text of over 2,750 articles, plus sophisticated search and retrieval functionality and links to the primary literature. The Encyclopaedia's authority is assured by editorial and advisory boards drawn from the world's foremost astronomers and astrophysicists. This first class resource is an essential source of information for undergraduates, graduate students, researchers and seasoned professionals, as well as for committed amateurs, librarians and lay people wishing to consult the definitive astronomy and astrophysics reference work.

The most comprehensive and up-to-date survey available on stellar structure and evolution, with a special emphasis on currently unsolved problems.

This specialized workshop was conceived during the workshop on "Non isotropic and Variable Outflows from Stars", which was held at the Space Telescope Science Institute in October, 1991. At that meeting, the four of us collectively decided that the time was ripe for an even more focussed discussion of the basic issues in the area of hot-star wind instability and its observable manifestations. Not that the big problems have been solved! Rather, we are currently in a phase of rapid development, both with regard to the models and to the observations. The key issue at this new workshop would be to decide how the time-dependent structures observed in hot-star winds (e. g. , NACs, DACs, blobs, clumps, filaments, shells, puffs, jets, etc. ) relate to radiative and other instabilities. Further questions concern the role of turbulence and the nature of its driver, and the effect of stellar rotation, pulsation, and magnetic fields on time-dependent phenomena in hot-star winds. Of no less importance is the impact of stellar wind variability on the derivation of mass-loss rates, on stellar evolution, and on momentum/energy deposition in the interstellar medium. To attain our goal of maximum confrontation (in the positive sense!) we decided: (1) to limit the workshop to the observers and theoreticians most active in this field in the world; (2) to insist that virtually all participants present a talk, thereby avoiding the distraction of poster sessions; and (3) to allocate approximately half of the allotted time to discussion.

This volume tries to summarize the status of observational knowledge of the Kuiper Belt. Its recent discovery has revitalized the astromomical study of the Solar System and is beginning to open new and unexpected windows on the physics of planetesimal accretion. With more and better observational data being obtained at the technological limit of current facilities, a new perception of the relationships that exist among the various classes of small Solar System bodies has emerged. The new observations have also motivated a number of fascinating theoretical studies in Solar System dynamics.