Nuclear-reaction rates in the thermonuclear runaway phase of accreting neutron starsM. Wiescher1, V. Barnard1, J.L. Fisker2, 3, J. Görres1, K. Langanke3, G. Martinez-Pinedo2, 3, F. Rembges2, H. Schatz4 and F.K. Thielemann2
1 Department of Physics, University of Notre Dame, Notre Dame, IN 46556-5670, USA
2 Department of Physics, University of Basel, CH-4056 Basel, Switzerland
3 Institute of Physics and Astronomy, University of Århus, DK-8000 Århus, Denmark
4 NSCL & Department of Physics, Michigan State University, East Lansing, MI 48824, USA
(Received: 21 March 2002 / Published online: 31 October 2002)
The rp-process has been suggested as the dominant nucleosynthesis process in explosive hydrogen burning at high temperature and density conditions. The process is characterized by a sequence of fast proton capture reactions and subsequent -decays. The reaction path of the rp-process runs along the drip line up to . Most of the charged-particle reaction rates for the reaction path are presently based on statistical Hauser-Feshbach calculations. While these rates are supposed to be reliable within a factor of two for conditions of high density in the compound nuclei, discrepancies may occur for nuclei near closed shells or near the proton drip line where the Q-values of proton capture processes are typically very small. It has been argued that the thermonuclear runaway is less sensitive to the reaction rates because of the rapid time-scale of the event. However, since these processes may operate at the same time-scale as fast mixing and convection processes, a change in reaction rates indeed may have a significant impact. In this paper we present two examples, the break-out from the hot CNO cycles, and the thermonuclear runaway in X-ray bursts itself, where changes in reaction rates have a direct impact on time-scale, energy generation and nucleosynthesis predictions for the explosive event.
21.60.Cs - Shell model.
26.30.+k - Nucleosynthesis in novae, supernovae and other explosive environments.
© Società Italiana di Fisica, Springer-Verlag 2002