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Abstract We consider the combined effects that overshooting and the12C(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 experimental12C(α,γ)16O reaction rate probability distribution function when overshooting is included in the evolution. These signatures hold because the resonating mantle region, encompassing ≃0.2M⊙in a typical ≃0.6M⊙WD model, still undergoes radiative helium burning during the evolution to a WD. Our specific models show two potential low-order adiabatic g-modes,g2andg6, that signalize the12C(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% forg2andg6, respectively. We find thatg6is a trapped mode, and theg2period signature is inversely proportional to the12C(α,γ)16O reaction rate. Theg6period 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 the12C(α,γ)16O reaction rate probability distribution function when overshooting is included in the evolution.
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This content will become publicly available on November 21, 2026
16 O + 16 O fusion at sub-coulomb energies
Abstract A simple optical model (OPM) method using non-monotonic (NM) potentials characterized by a repulsive core from the microscopic theory of the Pauli-led energy-density functional (EDF) has been developed to investigate the16O+16O fusion at sub-Coulomb energies relevant to the oxygen burning. The study involves the analysis of the experimental fusion cross-section (FCS) data in energy range 6.92 ≤Ecm≤ 13.83 MeV, which includes the Coulomb barrier regionEcm= 10.0–11.92 MeV. Apart from an excellent description of the existing FCS data in the studied energy range, the associated hindrance, characterized by theS-factor reaching a maximum and then gradually falling off at lower energies, so far suggested empirically for the system, is reproduced down to 4 MeV for the first time in the simple OPM. AnS-factor maximum ofS0 = 3.15 × 1025MeV.b atE0 = 7.14 MeV is observed withT ≃ 2.6 GK, which conforms to the values reported for quiescent and explosive burning. Our reaction rate, deduced from the NM potential, compares well with the Caughlan and Fowler data. Dominant partial waves implicit in the observed maximumS-factor in the studied Gamow range are also explored. Our present findings, with the success of NM potentials, suggest thatthe nucleus–nucleus potential is non-monotonic.
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- Award ID(s):
- 2310059
- PAR ID:
- 10663571
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Journal of Physics G: Nuclear and Particle Physics
- Volume:
- 52
- Issue:
- 11
- ISSN:
- 0954-3899
- Page Range / eLocation ID:
- 115103
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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