2004ApJ...608..983A

The Na, Mg, and Al abundance anomalies that have been observed in globular cluster red giants are hard to understand in terms of standard evolutionary scenarios, especially with regard to the depletion of ²⁴Mg. In previous papers, we have proposed a flash-assisted deep-mixing model that can burn ²⁴Mg and help explain the observed abundance anomalies. Relevant reaction rates have considerable uncertainties at low energies. Using NACRE reaction rates, we recompute the nucleosynthesis predicted by our model and, by adjusting reaction rates within current uncertainties, find that agreement with the observations is considerably improved for almost all isotopes except for ²⁵Mg, which remains overabundant. A resolution of the latter discrepancy by nuclear physics alone would require that the ²⁵Mg(p,γ)²⁶Al reaction rate be substantially larger than that given by the experiments. This suggests that our model may require burning of ²⁵Mg (coupled with some extra mixing) during quiescent hydrogen-burning phases.