Conventional star atlases are great for locating constellations and individual stars but The Star Atlas Companion goes one step further and describes the physical properties of more than 1,100 stars. With the aid of scale diagrams, the reader can get a real sense of the sizes, shapes, distances, and surface features of many of the stars visible to the naked eye in both the Nothern and Southern Hemispheres. Information on their rotational velocities and periods is given together with their spectral type and luminosity. Binary and multiple star systems are explained in detail. Special mention is made of Barnard's, Kapteyn's, Kepler's, and Van Maanen's Stars and the properties of many open clusters are given. With its emphasis on helping the amateur astronomer gain a better understanding of what they are looking at. The Star Atlas Companion will provide a new dimension to observing the star and is an invaluable supplement to any star atlas.

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.

No part of the Hertzsprung-Russell diagram shows a more pronounced diversity of stellar types than the upper part, which contains the most luminous stars. Can one visualize a larger difference than between a luminous, young and extremely hot Of star, and a cool, evolved pulsating giant of the Mira type, or an S-type supergiant, or - again at the other side of the diagram - the compact nucleus of a planetary nebula? But there is order and unity in this apparent disorder! Virtually all types of bright stars are evolutionally related, in one way or the other. Evolution links bright stars. In many cases the evolution is speeded up by, or at least intimately related to various signs of stellar instability. Bright stars lose mass, either continuously or in dramatic sudden events, they vibrate or pulsate - and with these tenuous, gigantic objects this often happens in a most bizarre fashion. Sometimes the evolution goes so fast that fundamental changes are observable in the time span of a human's life - several of such cases have now been identified.

The book begins with a historical introduction, "Star Formation: The Early History", that presents new material of interest for students and historians of science. This is followed by two long articles on "Pre-Main-Sequence Evolution of Stars and Young Clusters" and "Observations of Young Stellar Objects". These articles on the fascinating problem of star formation from interstellar matter give a thorough overview of present-day theories and observations. The articles contain material so far unpublished in the astronomical literature. The book addresses graduate students and can be used as a textbook for advanced courses in stellar astrophysics.