Strength of the E_R = 127 keV, 26Al(p,g)27Si resonance

TL;DR

This study investigates how the uncertain strength of a specific nuclear resonance affects the production of aluminum-26 in stellar explosions, finding that the yield is mostly insensitive to small variations but can decrease significantly with larger assumed strengths.

Contribution

The paper provides a detailed analysis of the impact of the 127 keV resonance strength on 26Al yields in stellar models, highlighting the need for new experimental measurements.

Findings

26Al yields are insensitive to small resonance strength variations.

Yields decrease up to 30% with larger assumed resonance strengths.

Current resonance strength limits are based on limited experimental data.

Abstract

We examine the impact of the strength of the E_R = 127 keV, 26Al(p,g)27Si resonance on 26Al production in classical nova explosions and asymptotic giant branch (AGB) stars. Thermonuclear 26Al(p,g)27Si reaction rates are determined using different assumed strengths for this resonance and representative stellar model calculations of these astrophysical environments are performed using these different rates. Predicted 26Al yields in our models are not sensitive to differences in rates determined using zero and a commonly stated upper limit corresponding to wg_UL = 0.0042 micro-eV for this resonance strength. Yields of 26Al decrease by 6% and, more significantly, up to 30%, when a strength of 24 x wg_UL = 0.1 micro-eV is assumed in the adopted nova and AGB star models, respectively. Given that the value of wg_UL was deduced from a single, background-dominated 26Al(3He,d)27Si experiment where only upper limits on differential cross sections were determined, we encourage new experiments to confirm the strength of the 127 keV resonance.