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Context. We test the e ffect of proton-capture reaction rate uncertainties on the ab undances of the Ne, Na, Mg and Al isotopes processed by the NeNa and MgAl chains during hot bottom burning (HBB) in asymp totic giant branch (AGB) stars of intermediate mass between 4 a d 6M⊙ and metallicities between Z = 0.0001 and 0.02. Aims. We provide uncertainty ranges for the AGB stellar yields, fo r inclusion in galactic chemical evolution models, and indi cate which reaction rates are most important and should be better determine d. Methods. We use a fast synthetic algorithm based on detailed AGB model s. We run a large number of stellar models, varying one reacti on per time for a very fine grid of values, as well as all reactions sim ultaneously. Results. We show that there are uncertainties in the yields of all the N e, Na, Mg and Al isotopes due to uncertain proton-capture rea ction rates. The most uncertain yields are those of 26Al and 23Na (variations of two orders of magnitude), 24Mg and27Al (variations of more than one order of magnitude),20Ne and22Ne (variations between factors 2 and 7). In order to obtain mo re reliable Ne, Na, Mg and Al yields from IM-AGB stars the rates that require more accurate determination ar e: 22Ne(p, γ)23Na,23Na(p, γ)24Mg, 25Mg(p, γ)26Al, 26Mg(p, γ)27Al and 26Al( p, γ)27Si. Conclusions. Detailed galactic chemical evolution models should be cons tructed to address the impact of our uncertainty ranges on th e observational constraints related to HBB nucleosynthesis, such as globular cluster chemical anomalies.

Reaction rate uncertainties and the operation of the NeNa and MgAl chains during HBB in intermediate-mass AGB stars