Friday, May 13, 2005, 16:00
WHGA Auditorium
F. Thielemann, Univ. Basel
Abstract:
With the exception of H, D, 3He, 4He and 7Li, originating from the Big
Bang, all heavier elements are produced in nucleosynthesis processes in
stellar evolution and stellar explosions (or interstellar cosmic ray
interactions acting on those elements). A brief initial introduction is
given to the physics in astrophysical plasmas which governs composition
changes, i.e. nuclear physics addressing cross sections for nuclear
reactions of stable and unstable nuclei, photo- disintegrations,
electron and positron captures, neutrino captures, inelastic neutrino
scattering, beta-decay or even fission. It follows a discussion of the
fate of massive stars, core collapse supernova explosions (SNe II), as
well as processes in binary systems containing white dwarfs or neutrons
stars. Mass accretion onto wite dwarfs leads to novae and type Ia
supernovae (SNe Ia), in case of neutron stars explosive hydrogen and
helium burning of accreted matter is the origin of X-ray bursts.
We address also the production of heavy elements in rapid neutron
capture processes up to Th, U and beyond and their possible origin from
stellar explosion sites. Finally a summary is given how all these
processes enter into the "chemical" (or better abundance) evolution of
galaxies.