Massive Star Modeling and Nucleosynthesis

Ekström, Sylvia

doi:10.3389/fspas.2021.617765

Cited by 10 publications

(3 citation statements)

References 309 publications

(364 reference statements)

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“…As N. Langer (2012) 15 put it, it is not even clear if the final product of He-burning is carbon or oxygen! Various studies show very different behavior for the reaction rate as a function of the temperature; see discussion and references in Ekström (2021). A comparison of various rates are shown in Figure 1 of El Eid et al (2004).…”

Section: Discussionmentioning

confidence: 98%

WO-type Wolf–Rayet Stars: The Last Hurrah of Massive Star Evolution*

Aadland

Massey

Hillier

et al. 2022

ApJ

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Are WO-type Wolf–Rayet (WR) stars in the final stage of massive star evolution before core-collapse? Although WC- and WO-type WRs have very similar spectra, WOs show a much stronger O vi λλ3811,34 emission-line feature. This has usually been interpreted to mean that WOs are more oxygen rich than WCs, and thus further evolved. However, previous studies have failed to model this line, leaving the relative abundances uncertain, and the relationship between the two types unresolved. To answer this fundamental question, we modeled six WCs and two WOs in the LMC using UV, optical, and NIR spectra with the radiative transfer code cmfgen in order to determine their physical properties. We find that WOs are not richer in oxygen; rather, the O vi feature is insensitive to the abundance. However, the WOs have a significantly higher carbon and lower helium content than the WCs, and hence are further evolved. A comparison of our results with single-star Geneva and binary BPASS evolutionary models show that, while many properties match, there is more carbon and less oxygen in the WOs than either set of evolutionary model predicts. This discrepancy may be due to the large uncertainty in the 12C+4He → 16O nuclear reaction rate; we show that if the Kunz et al. rate is decreased by a factor of 25%–50%, then there would be a good match with the observations. It would also help explain the LIGO/VIRGO detection of black holes whose masses are in the theoretical upper mass gap.

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Section: Discussionmentioning

confidence: 98%

WO-type Wolf–Rayet Stars: The Last Hurrah of Massive Star Evolution*

Aadland

Massey

Hillier

et al. 2022

ApJ

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show abstract

“…As N. Langer (2012) 9 put it, it is not even clear if the final product of He-burning is carbon or oxygen! Various studies show very different behavior of the reaction rate of as a function of the temperature; see discussion and references in Ekström (2021). A comparison of various rates are shown in Figure 1 of El Eid et al (2004).…”

Section: Discussionmentioning

confidence: 98%

WO-Type Wolf-Rayet Stars: the Last Hurrah of Massive Star Evolution

Aadland,

Massey,

Hillier

et al. 2022

Preprint

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Are WO-type Wolf Rayet (WR) stars in the final stage of massive star evolution before core-collapse? Although WC-and WO-type WRs have very similar spectra, WOs show a much stronger O vi λλ3811,34 emission-line feature. This has usually been interpreted to mean that WOs are more oxygen rich than WCs, and thus further evolved. However, previous studies have failed to model this line, leaving the relative abundances uncertain, and the relationship between the two types unresolved. To answer this fundamental question, we modeled six WCs and two WOs in the LMC using UV, optical, and NIR spectra with the radiative transfer code cmfgen in order to determine their physical properties. We find that WOs are not richer in oxygen; rather, the O vi feature is insensitive to the abundance. However, the WOs have a significantly higher carbon and lower helium content than the WCs, and hence are further evolved. A comparison of our results with single-star Geneva and binary BPASS evolutionary models show that while many properties match, there is more carbon and less oxygen in the WOs than either set of evolutionary model predicts. This discrepancy may be due to the large uncertainty in the 12 C+ 4 He→ 16 O nuclear reaction rate; we show that if the Kunz et al. rate is decreased by a factor of 25-50%, then there would be a good match with the observations. It would also help explain the LIGO/VIRGO detection of black holes whose masses are in the theoretical upper mass gap.

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“…Present reaction rates are therefore mostly based on theoretical model extrapolations, which require a detailed understanding of the quantum mechanical reaction mechanism at the energy threshold, including the effects of screening and nuclear clusters. Other fundamental, yet poorly understood, aspects of stars and their explosions include convection, mixing, rotation, magnetic fields, mass loss, and the influence of companion stars [46][47][48][49][50][51]. It is becoming clearer that while these effects critically impact element synthesis and nuclear reactions they cannot always be adequately modeled in spherical symmetry (one spatial dimension).…”

Section: Dynamic Nuclear Burning In Starsmentioning

confidence: 99%

Horizons: nuclear astrophysics in the 2020s and beyond

Schatz

Reyes

Best

et al. 2022

J. Phys. G: Nucl. Part. Phys.

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Nuclear astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities.

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Massive Star Modeling and Nucleosynthesis

Cited by 10 publications

References 309 publications

WO-type Wolf–Rayet Stars: The Last Hurrah of Massive Star Evolution*

WO-type Wolf–Rayet Stars: The Last Hurrah of Massive Star Evolution*

WO-Type Wolf-Rayet Stars: the Last Hurrah of Massive Star Evolution

Horizons: nuclear astrophysics in the 2020s and beyond

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