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L. Dessieux (Dept. Physics and Astronomy, U. Tennessee), M. S. Smith (ORNL Physics Division*), W. R. Hix (Dept. Physics and Astronomy, U. Tennessee), M. W. Guidry (Dept. Physics and Astronomy, U. Tennessee; ORNL Physics Division*)
During explosive hydrogen burning, the catalytic CNO cycle suffers depletion by additional thermonuclear capture reactions on the members of the cycle. This “break out” from the beta-limited CNO cycle has been suggested to occur in novae and X-ray bursts for temperatures greater than 0.4 GK. At these temperatures alpha captures can occur on the CNO waiting-point isotopes through the nuclear reactions 14O(alpha,p)17F, 15O(alpha,gamma)19Ne, and 18Ne(alpha,gamma)21Na. An additional reaction, 14O(alpha, 2p)16O has been suggested as a possible break out path from the CNO cycle. To investigate the astrophysical significance of the 14O(alpha,2p)16O reaction, we have carried out a detailed series of simulations under both nova and X-ray burst conditions in which the unknown rate for this new reaction was varied over a range of magnitudes. We conclude from these simulations that the unknown rate is not likely to have a significant influence on nova explosions because the temperatures are too low for it to come strongly into play. During an X-ray burst we find that the 14O(a,p) 17F reaction is pivotal for energy generation but the unmeasured 14O(a,2p)16O reaction has an insignificant effect on energy production and final abundances during the burst for any reasonable range of assumptions about its rate. Thus, we conclude that 14O(alpha, 2p)16O is not likely to play a significant role in nova or X-ray burst environments. In this presentation we shall give the details of the simulations leading to these conclusions.
*Managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-Ac05-00OR22725
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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.