Nuclear Reaction Rate Uncertainties and their effects on Nova Nucleosynthesis Modeling

The nucleosynthesis and other observable consequences of a nova outburst depend sensitively on the details of the thermonuclear runaway which initiates the outburst. One important source of uncertainty in our current models is the nuclear reaction data used as input for the evolutionary calculations. We present preliminary results of the first analyses of the impact on nova nucleosynthesis of all reaction rate uncertainties considered simultaneously. 1. Nuclear Uncertainties in Novae Observations of nova outbursts have revealed an elemental composition that differs markedly from solar. Theoretical studies indicate that these 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 C, N, and O. Such nuclei are difficult to form in other astrophysical hosts. Many of the proton-rich nuclei produced in nova outbursts are radioactive, offering the possibility of direct observation with γ-ray instruments. Potentially important γ-ray sources include Al, Na, Be, and F. The observable consequences of a nova outburst depend sensitively on the details of the thermonuclear runaway which initiates the outburst. One important source of uncertainty is the nuclear reaction data used as input for the evolutionary calculations (Starrfield et al. 1998). A number of features conspire to magnify the effects of nuclear uncertainties on nova nucleosynthesis. First, the similarity of the nuclear burning and convective timescales in Department of Physics & Astronomy, University of Tennessee, Knoxville, TN 37996-1200 Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6354 Managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725 Department of Physics & Astronomy, Arizona State University, Tempe, AZ 85287-1504 Technology Development Division, Argonne National Laboratory, Argonne, IL 60439