Direct measurements of 22Na(p,g)23Mg resonances and consequences for 22Na production in classical novae

TL;DR

This study directly measured key resonances in the 22Na(p,g)23Mg reaction, revealing higher resonance strengths than previously known, which significantly impacts the predicted 22Na abundance in classical novae.

Contribution

The paper provides the first direct, absolute measurements of low-energy 22Na(p,g)23Mg resonances using a radioactive target, refining the nuclear reaction rate relevant to nova nucleosynthesis.

Findings

Resonance strengths at specific energies are 2.4 to 3.2 times higher than previous estimates.

Excluded contributions from certain proposed resonances at low energies.

Predicted 22Na abundance in nova ejecta is reduced by about a factor of 2.

Abstract

The radionuclide 22Na is a potential astronomical observable that is expected to be produced in classical novae in quantities that depend on the thermonuclear rate of the 22Na(p,g)23Mg reaction. We have measured the strengths of low-energy 22Na(p,g)23Mg resonances directly and absolutely using a radioactive 22Na target. We find the strengths of resonances at E_p = 213, 288, 454, and 610 keV to be higher than previous measurements by factors of 2.4 to 3.2, and we exclude important contributions to the rate from proposed resonances at E_p = 198, 209, and 232 keV. The 22Na abundances expected in the ejecta of classical novae are reduced by a factor of ~ 2.