We describe a general yet simple method to analyse the propagation of nuclear
reaction rate uncertainties in a stellar nucleosynthesis and mixing context.
The method combines post-processing nucleosynthesis and mixing calculations
with a Monte Carlo scheme. With this approach we reanalyze the dependence of
theoretical oxygen isotopic ratio predictions in first dredge-up red giant
branch stars in a systematic way. Such predictions are important to the
interpretation of pre-solar Al_2 O_3 grains from meteorites. The reaction rates
with uncertainties were taken from the NACRE compilation (Angulo etal., 1999).
We include seven reaction rates in our systematic analysis of stellar models
with initial masses from 1 to 3 M_sun. We find that the uncertainty of reaction
rate for reaction O18(p,alpha)N15 typically causes an error in the theoretical
O16/O18 ratio of about +20/-5 per cent. The error of the O16/O17 prediction is
+-10 to 40 per cent depending on the stellar mass, and is persistently
dominated by the comparatively small uncertainty of the O16(p,gamma)F17
reaction. With the new estimates on reaction rate uncertainties by the NACRE
compilation, the p-capture reactions O17(p,alpha)N14 and O17(p,gamma)F18 have
virtually no impact on theoretical predictions for stellar mass <= 1.5 M_sun.
However, this is not the case for masses > 1.5 M_sun, where core mixing and
subsequent envelope mixing interact. In these cases where core mixing
complicates post-dredge-up surface abundances, uncertainty in other reactions
have a secondary but noticeable effect on surface abundances.Comment: 11 pages (with figures and tables at the end), 8 figures (11 .eps
files), submitted to MNRA