The astrophysical S-factor for α-3H radiative capture is calculated at astrophysical energies. We construct conserved two- and three-body electromagnetic currents, using minimal substitution in the explicit momentum dependence of the two- and three-nucleon interactions. The realistic Argonne υ18 two-nucleon and Urbana IX or Tucson—Melbourne three-nucleon interactions are considered for calculation. By extrapolation of results for the astrophysical S-factor at zero energy, the energy in the order of 1 keV and less is found to be S(0) = 0.107(0.112) keVb, with(without) three-body interactions in satisfactory agreement with other theoretical results and experimental data.
