▪ Abstract The formation and evolution of galaxies is one of the great outstanding problems of astrophysics. Within the broad context of hierachical structure formation, we have only a crude picture of how galaxies like our own came into existence. A detailed physical picture where individual stellar populations can be associated with (tagged to) elements of the protocloud is far beyond our current understanding. Important clues have begun to emerge from both the Galaxy (near-field cosmology) and the high redshift universe (far-field cosmology). Here we focus on the fossil evidence provided by the Galaxy. Detailed studies of the Galaxy lie at the core of understanding the complex processes involved in baryon dissipation. This is a necessary first step toward achieving a successful theory of galaxy formation.

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The New Galaxy: Signatures of Its Formation

The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries

The R-process and nucleochronology

Among the various processes responsible for the formation of the heavy elements in stars, the slow neutron capture process (s-process) is distinguished by the fact that it involves mostly stable isotopes. Therefore, the relevant nuclear physics data can be determined by experiments. With this rather reliable data basis, s-process nucleosynthesis offers an important testground of models for the late stages of stellar evolution, which are supposed to be the s-process site. The empirical counterpart for such models is the so-called classical s-process, a purely phenomenological picture, that is successfully used to derive the resulting abundances as well as information on the physical conditions during the s-process. The status of this classical approach is reviewed with emphasis on the implications for various stellar models of the s-process and in the light of results obtained by stellar spectroscopy. A brief account of the potential s-process chronometers is also presented.

https://iopscience.iop.org/article/10.1088/0034-4885/52/8/002/pdf

s-process nucleosynthesis-nuclear physics and the classical model

The 1983 Nobel Prize in Physics lecture is reprinted. The author reviews current understanding of the nucleosynthesis process in the stars of our Galaxy. (AIP)

K. Takahashi

Papers

The Re-187 - Os-187 chronology and chemical evolution of the Galaxy

The production and survival of 205 PB in stars, and the 205 Pb-205 TI s-process chronometry.

On the validity of the local approximation for the s-process in the OS region, and implications for the (R-187)-(Os-187) cosmochronology