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arXiv · 2401.06754

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

William Fox·Richard Longland·Caleb Marshall·Federico Portillo Chaves
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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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William Fox, Richard Longland, Caleb Marshall, Federico Portillo Chaves. 2024-01-12. High Resolution Study of $^{40}$Ca to Constrain Potassium Nucleosynthesis in NGC 2419. https://arxiv.org/abs/2401.06754

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