First inverse kinematics study of the
Ne22(p,γ)Na23
reaction and its role in AGB star and classical nova nucleosynthesis
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abstract
The abundances of sodium and oxygen are observed to be anti-correlated in all
well-studied globular clusters. Asymptotic giant branch (AGB) stars undergoing
hot bottom burning (HBB) are thought to be prime candidates for producing
sodium-rich oxygen-poor material and expelling it into the cluster ISM. The
22Ne(p,gamma)23Na reaction has been shown to strongly influence the amount of
23Na produced during HBB. This reaction is also important for classical novae
nucleosynthesis, with sensitivity studies showing that the abundances of
several isotopes in the Ne-Al region are significantly altered when varying the
reaction rate between available compilations. Here we present the first inverse
kinematics measurements of key resonances strengths as well as the direct
capture S-factor. Together, this study represents the largest centre of mass
energy range (149-1222 keV) over which this reaction has been measured in a
single experiment. Our results for low-energy resonances at Ecm=149, 181 and
248 keV are in good agreement with recent forward kinematics results; we also
find a direct capture S-factor consistent with the literature value of 62
keV.b. However, in the case of the important reference resonance at Ecm = 458
keV we find a strength value of wg=0.44 +/- 0.02 eV, which is significantly
lower than recent results. Using our new recommended rate we explore the impact
of these results on both AGB star and classical novae nucleosynthesis. In the
case of AGB stars we see very little abundance changes with respect to the rate
included in the STARLIB-2013. However, we observe changes of up to a factor of
2 in isotopes produced in both the carbon-oxygen (CO) and oxygen-neon (ONe)
classical novae models considered here. The 22Ne(p,gamma)23Na reaction rate is
now sufficiently well constrained to not significantly contribute toward
abundance uncertainties from classical novae nucleosynthesis models.
