Proceedings of the International Astronomical Union

Table of Contents - 2009 - Volume 5, Symposium S265 (Chemical Abundances in the Universe: Connecting First Stars to Planets)  

Contributed Papers

Nucleosynthesis Now and Then

S. E. Woosleya1, A. Hegera2, L. Robertsa1 and R. D. Hoffmana3

a1 Department of Asronomy and Astrophysics, UCSC Santa Cruz, CA 95064, USA email: woosley@ucolick.org

a2 School of Physics & Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA email: alex@physics.umn.edu

a3 Nuclear Computational Physics Group, Physics and Life Sciences Directorate, LLNL, Livermore, CA, 94550, USA email: hoffman21@llnl.gov

Abstract

Today we understand, to reasonable accuracy, the origin of most of the abundant elements in the sun and similar Population I stars. Given our relatively primitive ability to model supernova explosion mechanisms, stellar mass loss, and stellar mixing, this is a remarkable achievement. This understanding is possible, in part, because supernovae are highly constrained by their spectra, light curves and the sorts of remnants they leave. This same understanding extends to the major abundances seen in primitive metal-poor stars down to [Fe/H] > −4. In particular, one finds no compelling evidence for exotic energies or unusual stellar properties. There are exceptions, however. About half of the isotopes above iron, the r-process and the p-process with A < 130, still have an uncertain origin, both in the sun and in metal-poor stars. The abundances in the hyper-iron-poor stars ([Fe/H] < −4) also require a special explanation. We suggest that they represent the operation of a first generation of massive stars that produced almost exclusively C, N, and O and black holes, a generation in which 100 Mxs2299 were abundant, but stars over about 150 Mxs2299 and under 30 Mxs2299 were almost absent.