Reaction rates for the 39K(p ,γ )40Ca reaction

The magnesium-potassium anticorrelation observed in globular cluster NGC2419 can be explained by nuclear burning of hydrogen in hot environments. The exact site of this nuclear burning is, as yet, unknown. In order to constrain the sites responsible for this anticorrelation, the nuclear reactions involved must be well understood. The ³⁹K+p reactions are one such pair of reactions. Here, we report a new evaluation of the ³⁹K(p ,γ )⁴⁰Ca reaction rate by taking into account ambiguities and measurement uncertainties in the nuclear data. The uncertainty in the ³⁹K(p ,γ )⁴⁰Ca reaction rate is larger than previously assumed, and its influence on nucleosynthesis models is demonstrated. We find the ³⁹K(p ,γ )⁴⁰Ca reaction cross section should be the focus of future experimental study to help constrain models aimed at explaining the magnesium-potassium anticorrelation in globular clusters.