The cross section of the ^ { 16 } O ( \alpha , \gamma ) ^ { 20 } Ne capture reaction is analyzed at low energies where the direct capture mechanism is dominant .
For temperatures below T _ { 9 } = 0.2 the resulting astrophysical reaction rate is about a factor of two higher than in a recent compilation whereas the energy dependence of the astrophysical S-factor and the branching ratios to the ^ { 20 } Ne bound states are very similar to previous calculations .
The validity of the widely used detailed balance theorem for the inverse ^ { 20 } Ne ( \gamma , \alpha ) ^ { 16 } O photodisintegration rate is confirmed for the special case of high-lying first excited states .