High Resolution Study of $^{40}$Ca to Constrain Potassium Nucleosynthesis in NGC 2419

Author:

William Fox, Richard Longland, Caleb Marshall, Federico Portillo Chaves

Keyword:

Nuclear Experiment, Nuclear Experiment (nucl-ex), Solar and Stellar Astrophysics (astro-ph.SR)

journal:

date:

2024-01-12 00:00:00

Abstract

The globular cluster NGC 2419 was the first to exhibit a Mg-K anticorrelation, linked to hydrogen burning at temperatures between 80-260 MK. However, the key K-destroying reaction, $^{39}\mathrm{K}(p,\gamma)^{40}\mathrm{Ca}$, has a large rate uncertainty in this range. We significantly constrain this rate with a high resolution $^{39}\mathrm{K}(^{3}\mathrm{He},d)^{40}\mathrm{Ca}$ study. We resolve the E$_{\text{r}}^{\text{c.m.}} = 154$ keV resonance in $^{39}\mathrm{K}+p$ for the first time, increasing the previous rate by up to a factor 13 and reducing its $1\sigma$ width by up to a factor of 42. Reaction network calculations for NGC 2419 suggest that this could lower temperatures needed to reproduce the Mg-K anticorrelation.

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