Oscillator strengths for Mg+ transitions

Configuration interaction wavefunctions are used to derive oscillator strengths for transitions of the Mg⁺ ion, in particular that for the $$3s^2S\rightarrow4p^2P^0$$ multiplet near 1240 Å. By comparing calculations of different complexity a value for the multiplet oscillator strength of 4 × 10⁻⁴ is found with an error estimate of ± 1 × 10⁻⁴. This is significantly lower than that generally used in studies of the interstellar medium and the implications of this are briefly discussed. Oscillator strengths for other transitions between ²S and ²P⁰ levels are also tabulated.