Direct capture astrophysical S factors at low energy

We investigate the energy dependence of the astrophysical [Formula Presented] factors for the reactions [Formula Presented] the primary source of high-energy solar neutrinos in the solar [Formula Presented] chain, and [Formula Presented] an important reaction in the CNO cycle. Both of these reactions have predicted [Formula Presented] factors which rise at low energies; we find the source of this behavior to be a pole in the [Formula Presented] factor at a center-of-mass energy [Formula Presented] the point where the energy of the emitted photon vanishes. The pole arises from a divergence of the radial integrals.