Bøger af C. Chiosi

x about a sequence of reVlew lectures, each followed by contributed talks and discussions. The opening session was devoted to reviewing the most recent results concerning the determination of chemical abundances in particularly inte­ resting objects providing direct evidence for stellar nucleosynthesis (like planetary nebulae, supernovae and supernova remnants). In Session 2 recent results on some relevant nuclear reaction rates have been presented. Session 3 grouped the contributions concerning the quasi-static evolution of normal stars, its relevance for the nucleosynthesis of the varlOUS elements and isotopes, and the comparison of the evolutionary models with the observations. Session 4 addressed the important questions of identifying the precursors of both Type I and Type II supernovae, and of determining the detailed composition of the ejecta by explosive nucleosynthesis associated with these events. Finally, Session 5 was devoted to a presentation of recent calculations of the evolution of hypothetical pre-galactic very massive objects (in­ cluding their potential role in pre-galactic nucleosynthesis), and to reviewing the progress that has been made in understanding the chemical evolution of galaxies. The discussion during and after talks was spirited and contributed signi­ ficantly to the succes of the workshop. We regrett for not having been able of reporting it "in toto" in the proceedings. Nevertheless, we hope that what has been recorded may still give to the reader at least part of the excitement we have experienced during the ten days of the workshop.

As it was said by one of the participants to this workshop"e; In our attempts to understand the spectral evolution of galaxies, we are fortunate indeed to have the ability to look back in time and observe galaxies as they were billions of years ago. Perhaos in no other discipline is it possible to gain such a direct view to hJstory. The galaxies we seek to study are remote, their light faint, and thus only recently has it become technicaJlv feasible to sample the spectra of normal luminosity galaxies at lookback times of five billion years or more"e; .... or, perhaps. even to see galaxies in the process of their formation. or shortly afterwards. This fourth workshop organized by the "e;Advanced School ot Astronomy was indeed centered on the "e;Spectral Evolution of Galaxies"e;. on reviewing and discussing the relevant astrophysical processes and on assessing our current ability to model and understand the evolution of stellar populations. Following an opening session dealing with some outstanding questions of galaxy evolution. Session I addressed the specific problems of galaxy and star formation processes. topics of uncertainty and controversy to which IRAS observations may give novel perspectives. The properties of stellar populations in the local group of galaxies formed the basis of Session II. Session III dealt with the fundaments of the theory of spectral and photometrical evolution of stellar populations. and with recent developments in the theory of stellar structure. a necessary step to model and understand galactic evolution.