Re-analysis of the $^{24}$Mg($\alpha,\gamma$)$^{28}$Si reaction rate at stellar temperatures

TL;DR

This paper re-evaluates the $^{24}$Mg($ extalpha, extgamma$)$^{28}$Si reaction rate using recent data, confirming its stability at key stellar temperatures and refining its role in astrophysical models of X-ray bursts.

Contribution

The study provides a updated, more precise reaction rate for $^{24}$Mg($ extalpha, extgamma$)$^{28}$Si, reducing uncertainties in stellar nucleosynthesis modeling.

Findings

Reaction rate remains largely unchanged at stellar temperatures.

Unmeasured resonances at lower temperatures could increase the rate but are astrophysically insignificant.

This reaction is no longer a key factor in X-ray burst models.

Abstract

The $^{24}$Mg($\alpha,\gamma$)$^{28}$Si reaction influences the production of magnesium and silicon isotopes during carbon burning and is one of eight reaction rates found to significantly impact the shape of calculated X-ray burst light curves. The reaction rate is based on measured resonance strengths and known properties of levels in $^{28}$Si. The $^{24}$Mg($\alpha,\gamma$)$^{28}$Si reaction rate has been re-evaluated including recent additional indirect data. The reaction rate is substantially unchanged from previously calculated rates, especially at astrophysically important temperatures. Increases in the reaction rate could occur at lower temperatures due to as-yet unmeasured resonances but these increases have little astrophysical impact. The $^{24}$Mg($\alpha,\gamma$)$^{28}$Si reaction rate at temperatures relevant to carbon burning and Type I X-ray bursts is well constrained by the available experimental data. This removes one reaction from the list of eight previously found to be important for X-ray burst light curve model-observation comparisons.