The ground state of unstable \(^{26}\)Al nucleus (\(^{26}\)Al\(^{g}\)) with T\(_{1/2}\) = 0.717 Myr was the first radioactive isotope detected in the galaxy, via the characteristic 1.809 MeV \(\gamma \)-emission of \(^{26}\)Mg (Mahoney et al., Astrophys J 286:578, [1]). The observation is direct proof of ongoing stellar nucleosynthesis in our Galaxy and indicates that there are approximately 2–3 M\(_\odot \) of \(^{26}\)Al\(^{g}\) (Diehl et al., Nature 439:45, [2]). \(^{26}\)Al has an isomeric state (\(^{26}\)Al\(^{m}\)) which is prohibited to decay into \(^{26}\)Al\(^{g}\) due to the large spin difference. However, an equilibration between \(^{26}\)Al\(^{m}\) and \(^{26}\)Al\(^{g}\) could proceed via intermediate states and influence the abundance of \(^{26}\)Al\(^{g}\). Hence, the isomer could have an important influence on the production of \(^{26}\)Al\(^{g}\). A one consistent program is used to investigate the effects of \(^{26}\)Al\(^{m}\) on \(^{26}\)Al\(^{g}\) production by using a 20 M\(_\odot \) stellar model in its hydrogen core burning and C/Ne shell burning.
