New Determination of the <sup>12</sup>C(α, γ)<sup>16</sup>O Reaction Rate and Its Impact on the Black-hole Mass Gap

Shen, Y. P.; deBoer, R. J.; Li, E. T.; Li, Zhihong; Li, Yunju; Tang, Xiaodong; Pang, D. Y.; Adhikari, S.; Basu, Chinmay; Su, J.; Yan, S. Q.; Fan, Q. W.; Liu, Jiancheng; Chen, Chen; Han, Zhiyu; Li, Xinyue; Liu, Gang; Ma, Tianxing; Nan, Wei; Nan, Weike; Wang, Youbao; Zeng, Sheng; Zhang, Hao; Liu, Weiping

doi:10.3847/1538-4357/acb7de

Cited by 12 publications

(4 citation statements)

References 76 publications

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“…Notably, Kunz et al (2002) considerably lowered the nominal rate compared to the NACRE compilation. Shen et al (2023) also recently found a rate that was significantly higher than the values of Xu et al (2013) anddeBoer et al (2017). The value of the 12 C(α, γ) 16 O rate is therefore still uncertain.…”

Section: Nuclear Reactions In Rc Starsmentioning

confidence: 74%

Effect of nuclear reactions rates and core boundary mixing on the seismology of red clump stars

Noll,

Basu,

Hekker

2024

A&A

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Modeling of the stars in the red clump (RC), that is, core helium-burning stars that have gone through a He flash, is challenging because of the uncertainties associated with the physical processes in their core and during the helium flash. By probing the internal stellar structure, asteroseismology allows us to constrain the core properties of RC stars and eventually, to improve our understanding of this evolutionary phase. We aim to quantify the impact on the seismic properties of the RC stars of the two main core modeling uncertainties: core boundary mixing, and helium-burning nuclear reaction rates. Using the MESA stellar evolution code, we computed models with different core boundary mixing as well as different $3 and reac nuclear reaction rates. We investigated the impact of these parameters on the period spacing $ which is a probe of the region around the core. We find that different core boundary mixing schemes yield significantly different period spacings, with differences of 30\,s between the maximum $ value computed with semiconvection and maximal overshoot. We show that an increased rate of reac lengthens the core helium-burning phase which extends the range of $ covered by the models during their evolution. This results in a difference of 10\,s between the models computed with a nominal rate and a rate multiplied by 2, which exceeds the observational uncertainties. The effect of changing the 3alpha reaction rate is comparatively small. The core boundary mixing is the main source of uncertainty in the seismic modeling of RC stars. Moreover, the effect of the reac is non-negligible, even though it is difficult to distinguish from the effect of the mixing. This degeneracy could be seen more frequently in the future in the new seismic data from the PLATO mission and through theoretical constraints from numerical simulations.

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Section: Nuclear Reactions In Rc Starsmentioning

confidence: 74%

Effect of nuclear reactions rates and core boundary mixing on the seismology of red clump stars

Noll,

Basu,

Hekker

2024

A&A

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“…This feature has often been attributed to the pulsational pairinstability pileup (e.g., Talbot & Thrane 2018;Farr et al 2019;Stevenson et al 2019), which would agree with our result presented here. However, recent updates of the tabulated 12 C(α, γ) 16 O reaction rates have pushed the lower boundary of PPISN, and the corresponding expected location of a pileup in the remnant mass distribution, to higher masses (Farmer et al 2020;Farag et al 2022;Mehta et al 2022;Hendriks et al 2023;Shen et al 2023). More updated prescriptions would therefore not result in a PPISN, but in direct core-collapse supernova.…”

Section: Binary Black Hole Formation and Potential Pairinstability Pu...mentioning

confidence: 99%

Investigating the Chemically Homogeneous Evolution Channel and Its Role in the Formation of the Enigmatic Binary Black Hole Progenitor Candidate HD 5980

Sharpe,

van Son,

de Mink

et al. 2024

ApJ

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Chemically homogeneous evolution (CHE) is a promising channel for forming massive binary black holes. The enigmatic, massive Wolf–Rayet binary HD 5980 A&B has been proposed to have formed through this channel. We investigate this claim by comparing its observed parameters with CHE models. Using MESA, we simulate grids of close massive binaries, then use a Bayesian approach to compare them with the stars’ observed orbital period, masses, luminosities, and hydrogen surface abundances. The most probable models, given the observational data, have initial periods ∼3 days, widening to the present-day ∼20 days orbit as a result of mass loss—correspondingly, they have very high initial stellar masses (≳150 M ⊙). We explore variations in stellar-wind mass loss and internal mixing efficiency, and find that models assuming enhanced mass loss are greatly favored to explain HD 5980, while enhanced mixing is only slightly favored over our fiducial assumptions. Our most probable models slightly underpredict the hydrogen surface abundances. Regardless of its prior history, this system is a likely binary black hole progenitor. We model its further evolution under our fiducial and enhanced wind assumptions, finding that both stars produce black holes with masses ∼19–37 M ⊙. The projected final orbit is too wide to merge within a Hubble time through gravitational waves alone. However, the system is thought to be part of a 2+2 hierarchical multiple. We speculate that secular effects with the (possible) third and fourth companions may drive the system to promptly become a gravitational-wave source.

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“…This is a unique process, setting stringent conditions for helium ignition. The 3α process is followed by the α-capture reaction 12 C(α, γ) 16 O, converting the 12 C into 16 O (deBoer et al 2017;Mehta et al 2022;Shen et al 2023). These two isotopes are the principal products of helium burning.…”

Section: Introductionmentioning

confidence: 99%

Seismic Signatures of the ¹²C(α, γ)¹⁶O Reaction Rate in White Dwarf Models with Overshooting

Chidester,

Timmes,

Farag

2023

ApJ

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We consider the combined effects that overshooting and the 12C(α, γ)16O reaction rate have on variable white dwarf (WD) stellar models. We find that carbon–oxygen (CO) WD models continue to yield pulsation signatures of the current experimental 12C(α, γ)16O reaction rate probability distribution function when overshooting is included in the evolution. These signatures hold because the resonating mantle region, encompassing ≃0.2 M ⊙ in a typical ≃0.6 M ⊙ WD model, still undergoes radiative helium burning during the evolution to a WD. Our specific models show two potential low-order adiabatic g-modes, g 2 and g 6, that signalize the 12C(α, γ)16O reaction rate probability distribution function. Both g-mode signatures induce average relative period shifts of ΔP/P = 0.44% and ΔP/P = 1.33% for g 2 and g 6, respectively. We find that g 6 is a trapped mode, and the g 2 period signature is inversely proportional to the 12C(α, γ)16O reaction rate. The g 6 period signature generally separates the slower and faster reaction rates, and has a maximum relative period shift of ΔP/P = 3.45%. We conclude that low-order g-mode periods from CO WDs may still serve as viable probes for the 12C(α, γ)16O reaction rate probability distribution function when overshooting is included in the evolution.

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New Determination of the ¹²C(α, γ)¹⁶O Reaction Rate and Its Impact on the Black-hole Mass Gap

Cited by 12 publications

References 76 publications

Effect of nuclear reactions rates and core boundary mixing on the seismology of red clump stars

Effect of nuclear reactions rates and core boundary mixing on the seismology of red clump stars

Investigating the Chemically Homogeneous Evolution Channel and Its Role in the Formation of the Enigmatic Binary Black Hole Progenitor Candidate HD 5980

Seismic Signatures of the ¹²C(α, γ)¹⁶O Reaction Rate in White Dwarf Models with Overshooting

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New Determination of the 12C(α, γ)16O Reaction Rate and Its Impact on the Black-hole Mass Gap

Cited by 12 publications

References 76 publications

Effect of nuclear reactions rates and core boundary mixing on the seismology of red clump stars

Effect of nuclear reactions rates and core boundary mixing on the seismology of red clump stars

Investigating the Chemically Homogeneous Evolution Channel and Its Role in the Formation of the Enigmatic Binary Black Hole Progenitor Candidate HD 5980

Seismic Signatures of the 12C(α, γ)16O Reaction Rate in White Dwarf Models with Overshooting

Contact Info

Product

Resources

About

New Determination of the ¹²C(α, γ)¹⁶O Reaction Rate and Its Impact on the Black-hole Mass Gap

Seismic Signatures of the ¹²C(α, γ)¹⁶O Reaction Rate in White Dwarf Models with Overshooting