UNSTABLE NUCLEI IN ASTROPHYSICS

Astrophysical simulations require the knowledge of a wealth of nuclear reactions, which (a) explain the synthesis and abundance patterns of nuclei in nature, and (b) are the energy source of many stellar events via static or explosive nuclear burning. Especially in explosive burning, many unstable nuclei can be produced. Dependent on the total neutron/proton ratio of the fuel composition (hydrogen-rich or neutron-rich), nuclei close to the proton or neutron drip lines can be produced and it is of paramount importance to know their masses, decay properties, and reaction cross sections. After a brief review of hydrostatic burning stages in stellar evolution, we focus on explosive burning and the three processes (p or gamma-process, rp-process, and r-process), which produce unstable nuclei in supernovae, novae, and X-ray bursts. The observed abundance pattern of stable nuclei and nuclear-physics knowledge far from stability can be of great use to constrain the conditions in astrophysical production sites.