Joint Nuclear Astrophysics Seminar

There are about 35 proton-rich nuclei whose production cannot be explained by neutron capture processes. The synthesis of these so-called p nuclei is thought to be realized in different astrophysical scenarios which are usually referred to as sites of p-process nucleosynthesis. These scenarios will be briefly introduced including the different approaches to determine the nuclear physics needed for their modelling. As a highlight, the production of the lightest p nuclei via proton capture reactions in thermonuclear supernovae will be presented. Two recent publications [1,2] found a significant contribution to the production of the most abundant p nucleus 92-Mo by this mechanism. Experimental approaches for the determination of the required reaction rates will be explained and first results will be shown.
[1] C. Travaglio et al., The Astrophysical Journal 739 (2011) 93
[2] M. Kusakabe et al., The Astrophysical Journal 726 (2011) 25

Stellar spectra carry a wealth of information, and depending on their resolution we can extract e.g. the stellar ages, chemical composition, radial velocities, as well as the stellar parameters. By observing a large sample of different stars with high-resolution spectrographs, we can investigate the chemical evolution, of all elements detectable, from lithium to uranium. Furthermore, knowing the complete abundance pattern of the star enables a comparison with model predictions, which in turn will provide information on the formation site and process of the detected elements.
In this way stellar abundances are chemical tracers. Hence, they can guide our understanding of nuclear processes, and thereby link nuclear physics (e.g. reaction rates), through astrophysics theory (such as yield predictions) to astronomy (chemical evolution and stellar abundances).

In this talk I will outline how stellar abundances are derived and used in a chemical evolution scheme. The main focus is on the heavy elements (Sr, Y, Zr, Mo, Pd, Ag, Ba, Nd, and Eu), and how these can be used as tracers of their formation processes.