The Astrophysical r-Process From to Present K.-L. Kratz 1 , P. Möller 2 , B. Pfeiffer 1 , and F.-K. Thielemann 3 1 Institut für Kernchemie, Universität Mainz, D-55128 Mainz, Germany, 2 P. Moller Scientific Computing and Graphics, Inc., Los Alamos, NM87545, USA, 3 Departement für Physik und Astronomie, Universität Basel, CH-4056 Basel, Switzerland klkratz@vkcmzd. chemie. unimainz. de Abstract: In 1957, Burbidge, Burbidge, Fowler and Hoyle provided a basis for forty years of research in various aspects of nucleosynthesis in stars. We will focus in this paper on progress in r-process nucleosynthesis, with emphasis on the most recent developments in nuclear physics. In 1986, the first experimen- tal data on two crucial, neutron-magic “waiting-point” nuclei provided valu- able clues to the astrophysical conditions and the nature of the r-process site. Beginning in the 1990's, our group presented considerably improved r- abundance calculations, which were for the first time based on a modern, internally consistent nuclear-theory input. The phenomenon of shell- quenching far from stability required at that time seems to become evident by now. This new nuclear-structure phenomenon leads to improved predic- tions of astrophysical observables like the solar-system isotopic r-abundances or the recently observed abundances of ultra-metal-poor halo stars. 1. INTRODUCTION Summarizing the knowledge about nucleosynthesis in stars in the mid 1950’s, in their famous review about the “Synthesis of the Elements in Stars”, Burbidge, Burbidge, Fowler and Hoyle (1957; in the following referred to as ) combined progress from stellar evolution and solar- system abundances with nuclear-physics data to explain how stars can produce all known nuclear species in eight separate processes, some of them still being denoted today by the well-known lettering notation e, s, r, and p. At the same time, several groups were working along similar lines, (Coryell, 1956, 1961; Cameron, 1957; Suess and Urey, 1956). Their papers Origin of Elements in the Solar System: Implications of Post-1957 Observations. Edited by O. Manuel, Kluwer Academic/Plenum Publishers, 2000. 119