Galactic Chemical Evolution in the Gaia Era
Key Uncertain Reaction Rates in Stellar Evolution
Christian Aa. Diget
Nuclear processes driving the energy production and nucleosynthesis in stars often cannot be studied directly in the laboratory. In many cases the reactions involve short-lived nuclei and are hindered by the Coulomb repulsion of the nuclei, making direct observation of the reactions difficult or even impossible. This is the case for reactions related to the last burning phases of stars in general, such as reactions relating to 26Al production and to the breakout from the Hot-CNO cycle in X-ray bursts. These and other key reactions are triggered by the absorption of a helium ion, and are therefore hindered by a large Coulomb barrier. Furthermore, since the reactions often involve radioactive isotopes, direct measurements of the reactions are impeded by the difficulty in producing sufficiently intense beams of the involved isotopes. The talk will introduce alternative, indirect, measurements of the key reactions, as well as some of the accelerators and highly segmented coincidence arrays utilised in the measurements.
16:30 - 18:00