Sensitivity to Thermonuclear Reaction Rates in Modeling the Abundance Anomalies of NGC 2419

doi:10.3847/1538-4357/aa8ad0

Title: Sensitivity to Thermonuclear Reaction Rates in Modeling the Abundance Anomalies of NGC 2419

Abstract

Abundance anomalies in globular clusters provide strong evidence for multiple stellar populations within each cluster. These populations are usually interpreted as distinct generations, with the currently observed second-generation stars having formed in part from the ejecta of massive, first-generation "polluter" stars, giving rise to the anomalous abundance patterns. The precise nature of the polluters and their enrichment mechanism are still unclear. Even so, the chemical abundances measured in second-generation stars within the globular cluster NGC 2419 provide insight into this puzzling process. Previous work used Monte Carlo nuclear reaction network calculations to constrain the temperature–density conditions that could reproduce the observed abundances, thereby placing robust limits on the origins of the polluter material. The effect of individual reaction rates on these conditions has not been studied, however. Thus, we perform an exhaustive sensitivity study on the nuclear physics input to determine which reactions have the greatest impact on these predictions. We find that the $${}^{30}$$Si(p,γ)$${}^{31}$$P, $${}^{37}$$Ar(p,γ)$${}^{38}$$K, $${}^{38}$$Ar(p,γ)$${}^{39}$$K, and $${}^{39}$$K(p,γ)$${}^{40}$$Ca reactions are all critical in determining the temperature–density conditions, and ultimately, the origins of the polluter material. We conclude with recommendations for future experiments.

Authors:

Dermigny, J. R. ^[1]; Iliadis, C. ^[1]

Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States)

Publication Date:: 2017-10-05

Research Org.:: Univ. of North Carolina, Chapel Hill, NC (United States)

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 1511015

Grant/Contract Number:: [FG02-97ER41041]

Resource Type:: Accepted Manuscript

Journal Name:: The Astrophysical Journal (Online)

Additional Journal Information:: [Journal Name: The Astrophysical Journal (Online); Journal Volume: 848; Journal Issue: 1]; Journal ID: ISSN 1538-4357

Publisher:: Institute of Physics (IOP)

Country of Publication:: United States

Language:: English

Subject:: 79 ASTRONOMY AND ASTROPHYSICS

Citation Formats


                    Dermigny, J. R., and Iliadis, C. Sensitivity to Thermonuclear Reaction Rates in Modeling the Abundance Anomalies of NGC 2419.  United States: N. p., 2017. 
        Web.  doi:10.3847/1538-4357/aa8ad0.

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                    Dermigny, J. R., & Iliadis, C. Sensitivity to Thermonuclear Reaction Rates in Modeling the Abundance Anomalies of NGC 2419.  United States.  doi:10.3847/1538-4357/aa8ad0.

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                    Dermigny, J. R., and Iliadis, C. Thu .  
        "Sensitivity to Thermonuclear Reaction Rates in Modeling the Abundance Anomalies of NGC 2419".  United States.  doi:10.3847/1538-4357/aa8ad0.  https://www.osti.gov/servlets/purl/1511015.

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@article{osti_1511015,

  title        = {Sensitivity to Thermonuclear Reaction Rates in Modeling the Abundance Anomalies of NGC 2419},

  author       = {Dermigny, J. R. and Iliadis, C.},

  abstractNote = {Abundance anomalies in globular clusters provide strong evidence for multiple stellar populations within each cluster. These populations are usually interpreted as distinct generations, with the currently observed second-generation stars having formed in part from the ejecta of massive, first-generation "polluter" stars, giving rise to the anomalous abundance patterns. The precise nature of the polluters and their enrichment mechanism are still unclear. Even so, the chemical abundances measured in second-generation stars within the globular cluster NGC 2419 provide insight into this puzzling process. Previous work used Monte Carlo nuclear reaction network calculations to constrain the temperature–density conditions that could reproduce the observed abundances, thereby placing robust limits on the origins of the polluter material. The effect of individual reaction rates on these conditions has not been studied, however. Thus, we perform an exhaustive sensitivity study on the nuclear physics input to determine which reactions have the greatest impact on these predictions. We find that the ${}^{30}$Si(p,γ)${}^{31}$P, ${}^{37}$Ar(p,γ)${}^{38}$K, ${}^{38}$Ar(p,γ)${}^{39}$K, and ${}^{39}$K(p,γ)${}^{40}$Ca reactions are all critical in determining the temperature–density conditions, and ultimately, the origins of the polluter material. We conclude with recommendations for future experiments.},

  doi          = {10.3847/1538-4357/aa8ad0},

  journal      = {The Astrophysical Journal (Online)},

  number       = [1],

  volume       = [848],

  place        = {United States},

  year         = {2017},

  month        = {10}

}

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DOI: 10.3847/1538-4357/aa8ad0

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Figures / Tables:

Figure 1: (Top) Constant temperature–density conditions that reproduce measured abundances in NGC 2419. The red dots result from runs with fixed reaction rates, while the blue dots result from runs with varying rates. (Bottom) The projection of acceptable solutions onto the temperature axis. Note that the red histogram has beenmore »

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