出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Many observational studies of metal-poor stars that exhibit large excesses of r-process elements
have been made in the past decade, and have provided useful constraints on modeling this process.
Recent abundance studies have revealed the existence of extremely metal-poor stars that
have large enhancements exclusively of the light neutron-capture elements, indicating that a nucleosynthesis
process that efficiently yields these elements operated in the very early Galaxy. We
review these recent measurements of light neutron-capture elements in the field halo stars, including
the most iron-deficient star known, as well as stars in metal-poor globular clusters. The
abundance pattern produced by this process and possible astrophysical sites are discussed. We
also discuss a group of metal-poor stars that exhibit double enhancements of s- and r-process elements,
which have been recently discovered through observations of carbon-enhancedmetal-poor
stars. Observational constraints on the corresponding processes responsible for this signature are
presented.
