Members and guests of the International Astronomical Union, ladies and gentlemen, it gives me great pleasure to welcome you to the Joint Discussion on ‘Nucleogenesis in Stars’. Let me first of all express my appreciation for the help given me by the other two members of the organizing committee, Dr A. G. Masevich of the U.S.S.R. and Prof. F. Hoyle of Great Britain. I am also very grateful to Prof. D. A. Frank-Kamenetsky who has consented to serve as secretary of the meeting.

I would like to take this opportunity to make some introductory remarks concerning nucleogenesis in stars and to sketch the outline of the program. Fig. 1 shows schematically the various nuclear processes by which all the elements and their isotopes may be synthesized in several generations of stars starting with pure or almost pure hydrogen as the composition of the first stars which formed in the Galaxy. In the figure, hydrogen burning reactions are plotted horizontally, helium burning and more complicated processes are plotted vertically. Neutron capture processes are shown as curved arrows.

In the preceeding reports an elegant theory of the origin of the elements has been outlined. This theory aims to be a comprehensive one. With the exception of D, Li, Be, B, the origin of all other nuclides is explained by thermonuclear reactions and subsequent neutron capture. But some difficulties arise in connexion with two groups of nuclides: the iron peak and the by-passed nuclei.