Impact of newly measured ²⁶Al(n, p)²⁶Mg and ²⁶Al(n, α)²³Na reaction rates on the nucleosynthesis of ²⁶Al in stars

The cosmic production of the short-lived radioactive nuclide ²⁶Al is crucial for our understanding of the evolution of stars and galaxies. However, simulations of the stellar sites producing ²⁶Al are still weakened by significant nuclear uncertainties. We re-evaluate the ²⁶Al(n, p)²⁶Mg, and ²⁶Al(n, α)²³Na ground state reactivities from 0.01 GK to 10 GK, based on the recent n TOF measurement combined with theoretical predictions and a previous measurement at higher energies, and test their impact on stellar nucleosynthesis. We computed the nucleosynthesis of low- and high-mass stars using the Monash nucleosynthesis code, the NuGrid mppnp code, and the FUNS stellar evolutionary code. Our low-mass stellar models cover the 2-3 M☉ mass range with metallicities between Z = 0.01 and 0.02, their predicted ²⁶Al/²⁷Al ratios are compared to 62 meteoritic SiC grains. For high-mass stars, we test our reactivities on two 15 M☉ models with Z = 0.006 and 0.02. The new reactivities allow low-mass AGB stars to reproduce the full range of ²⁶Al/²⁷Al ratios measured in SiC grains. The final ²⁶Al abundance in high-mass stars, at the point of highest production, varies by a factor of 2.4 when adopting the upper, or lower limit of our rates. However, stellar uncertainties still play an important role in both mass regimes. The new reactivities visibly impact both low- and high-mass stars nucleosynthesis and allow a general improvement in the comparison between stardust SiC grains and low-mass star models. Concerning explosive nucleosynthesis, an improvement of the current uncertainties between T9∼0.3 and 2.5 is needed for future studies.