Speaker
Description
The 12C(α, γ)16O reaction is one of the most crucial reactions in nuclear astrophysics, and thus in the past several decades attracts great efforts that further our understanding of this fundamental reaction [1]. The properties of several states in 16O strongly affect the 12C(α, γ)16O reaction rate. In recent years we developed an independent technique based on the (11B, 7Li) transfer reaction [2,3], and with this technique constrained the contributions from the external capture [4] and two subthreshold resonances [5,6] by measurement of properties of the ground state and the excited states at Ex = 6.917 MeV and 7.117 MeV in 16O. An increase of up to 21% in the total reaction rate is found within the temperature range of astrophysical relevance compared with the previous recommendation of a recent review. The updated 12C(α, γ)16O reaction rate decreases the lower and upper edges of the mass gap of black holes about 12% and 5%, respectively [7]. Furthermore, we found that in a sufficiently hot and dense astrophysical environment the 12C(α, γ)16O rate is enhanced by a factor of 8.1 at typical temperature of 0.1 GK in inner AGB stars due to change of the effective width of the excited state at Ex = 9.558 MeV of 16O. Such enhanced rate well matches the observations of single CEMP stars with the stellar modelling, and thus presents an explanation of the formation of single CEMP stars [8].
References:
[1] R. J. deBoer, J. Görres, M. Wiescher et al., Rev. Mod. Phys. 89, 035007 (2017).
[2] Y. P. Shen, B. Guo, T. L. Ma et al., Phys. Lett. B 797, 134820 (2019).
[3] Y. P. Shen, B. Guo, W. P. Liu, Prog. Part. Nucl. Phys. 119, 103857 (2021).
[4] Y. P. Shen, B. Guo, R. J. deBoer et al., Phys. Rev. Lett. 124, 162701 (2020).
[5] Y. P. Shen, B. Guo, Z. H. Li et al., Phys. Rev. C 99, 025805 (2019).
[6] W. Nan, Y. P. Shen, B. Guo et al., Phys. Rev. C 109, 045808 (2024).
[7] Y. P. Shen, B. Guo, R. C. DeBoer et al., Astrophys. J. 945, 41 (2023).
[8] G. Fu, Z. An, S. Jin, B. Guo, submitted.
