Abstract

Invited Talk - Plenary

Tuesday, 14 September 2021, 11:30

Origin of the Elements in the Universe

Friedrich-Karl Thielemann
University of Basel

What is the world made of? Ancient philosophers postulated four or five elements. Much later Dimitri Mendeleev and Lothar Meyer extended the quest to a rapidly expanding table of chemical elements. Using spectral analysis techniques that they had pioneered earlier, Kirchhoff and Bunsen discovered Fraunhofer lines in the solar spectrum, which showed that the elements found on Earth also existed in stars, though in different proportions. The abundance tabulations of Goldschmidt and later Suess and Urey showed a standard pattern for the solar system, which astronomers today extend to objects throughout the cosmos. How can those observations be explained? In 1957, independent of each other, two teams (1) J. and M. Burbidge, W. Fowler, and F. Hoyle, and (2) A.G.W. Cameron, worked on the first comprehensive ideas to understand the origin of the full current solar abundance pattern. Based on these foundations, extended progress has occurred over the past more than 60 years, starting with the physics entering astrophysical environments/objects from the big bang, over the structure, evolution, and the (explosive?) endpoints of stars, explosive events in binary systems, their nucleosynthesis, to finally their contribution to the evolution of galaxies, requiring a background in thermodynamics, radiation transport, and nuclear/particle physics determining nuclear properties and the burning in hot astrophysical plasmas. This includes the evolution of low- and intermediate mass stars and their planetary nebula endpoints, combined with the working of the s-process; stellar core-collapse to neutron stars and black holes, related to supernovae features and their explosive nucleosynthesis; explosive events in binary systems, like novae and X-ray bursts, type Ia supernovae, and compact binary mergers. As X-ray bursts and compact binary mergers are sites of explosive nucleosynthesis far from stability (on the proton- and neutron-rich side of stable nuclei), nuclear properties far from stability are an essential ingredient for the rp- and r-process and the formation of heavy nuclei beyond Fe. All these nucleosynthesis sites and processes enter galactic chemical evolution. A crucial test for the related model inputs comes from the observation of individual (explosive) events as well as their imprint on the abundance patterns of low-metallicity stars that are witnesses of the early evolution of galaxies as a function of time and metallicity. We hope that this will be an enjoyable journey through the cosmos and the production of the elements throughout its evolution!