Updated stellar rates for the reaction 23Mg(p,g )24Al are calculated by using all available experimental information on 24Al excitation energies. Proton and g -ray partial widths for astrophysically important resonances are derived from shell-model calculations. Correspondences of experimentally observed 24Al levels with shell-model states are based on application of the isobaric multiplet mass equation. Our new rates suggest that the 23Mg(p,g )24Al reaction influences the nucleosynthesis in the mass A.20 region during thermonuclear runaways on massive white dwarfs
