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W.R. Hix (JIHIR/UTenn/ORNL), M.S. Smith (ORNL), A. Mezzacappa (ORNL/UTenn), S. Starrfield (ASU)
Viewed originally as the sudden appearance of a new star, nova stella, novae have had a long history of studies with a variety of techniques. Observational studies have revealed an elemental composition that differs markedly from solar. Theoretical studies show that the differences are caused by the combination of convection with explosive hydrogen burning which results in a unique nucleosynthesis that is rich in odd numbered nuclei such as 15N, 17O and 13C. These nuclei are difficult to form in other astrophysical events.
The observable consequences of a nova outburst depend sensitively on the details of the thermonuclear runaway which initiates the outburst. One of the more important sources of uncertainty is the nuclear reaction data used as input for the evolutionary calculations. A recent paper by Starrfield, Truran, Wiescher & Sparks (1998) has demonstrated that changes in the reaction rate library used within a nova simulation have significant effects, not just on the production of individual isotopes (which can change by an order of magnitude), but on global observables such as the peak luminosity and the amount of mass ejected. We will present preliminary results of systematic analyses of the impact of reaction rate uncertainties on nova nucleosynthesis. While the primary goal of our studies is to discern the extent to which theory is discrepant from observations, we will also determine the relative importance of changes in individual reaction rates and provide guidance in the selection of reactions for further experimental study.