The origin of the elements and the history of their creation in the Universe is the essential stepping stone in order to provide the necessary prerequisites for any bio-chemistry leading to the appearance of life.
The recent high precision measurements of the cosmic microwave background established clearly that only H, He and Li are originating in the Big Bang. Thus, stars had to do the job for all of the heavier elements. Already early concepts from the 1950s led to the conclusion, that the production of elements heavier than Fe and Ni requires free neutrons.
The mechanisms of two processes (a slow and a rapid neutron capture process) have been identified, but only the first (the s-process) is understood from stellar evolution. Recent observations of low metallicity stars as well as radioactive debris in deep-sea sediments indicate that the second (the r-process) is originating from very rare events.
The seminar will discuss options and possible solutions to this puzzle: 1. the neutrino wind in core collapse supernovae, 2. jet ejecta from magneto-rotationally driven (MHD) supernovae, and 3. neutron star mergers.
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