The Impact of $^{12}$C($α, γ$)$^{16}$O Reaction on the Presupernova Evolution and Supernova Explodability of Massive Stars
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| Format: | Preprint |
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2025
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| author | Xin, Wenyu Nomoto, Ken'ichi Zhao, Gang |
| author_facet | Xin, Wenyu Nomoto, Ken'ichi Zhao, Gang |
| contents | Among the uncertainties of stellar evolution theory, we investigate how the $^{12}$C($α, γ$)$^{16}$O reaction rate affects the evolution of massive stars for the initial masses of $M ({\rm ZAMS})=$ 13 - 40 M$_\odot$ and the solar metallicity. We show that the {\sl explodability} of these stars, i.e., which of a neutron star (NS) or a black hole (BH) is formed, is sensitive to the strength of convective shell burning of C and O, and thus the mass fractions of C ($X$(C)) and O in the shell. For the small $^{12}$C($α, γ$)$^{16}$O reaction rate that yields larger $X$(C), $X$(C) is further enhanced by mixing of C from the overlying layer and then C shell burning is strengthened. The extra heating by C shell burning tends to prevent the contraction of outer layers and decrease the {\sl compactness parameter} at $M_r$ = 2.5 M$_\odot$. This effect leads to the formation of smaller mass cores of Si and Fe and steeper density and pressure gradients at the O burning shell in the presupernova models. If the pressure gradient there is steeper, the model is more likely to explode to form a NS rather than a BH. We describe the pressure gradient against $M_r$ with $V/U$ and the density drop with $1/U$, where $U$ and $V$ are non-dimensional variables to describe the stellar structure. We estimate the critical values of $V/U$ and $1/U$ at the O-burning shell above which the model is more likely to explode. We conclude that the smaller $^{12}$C($α, γ$)$^{16}$O reaction rate makes the mass range of $M ({\rm ZAMS})$ that forms a NS larger. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2502_11012 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Impact of $^{12}$C($α, γ$)$^{16}$O Reaction on the Presupernova Evolution and Supernova Explodability of Massive Stars Xin, Wenyu Nomoto, Ken'ichi Zhao, Gang Solar and Stellar Astrophysics Astrophysics of Galaxies High Energy Astrophysical Phenomena Among the uncertainties of stellar evolution theory, we investigate how the $^{12}$C($α, γ$)$^{16}$O reaction rate affects the evolution of massive stars for the initial masses of $M ({\rm ZAMS})=$ 13 - 40 M$_\odot$ and the solar metallicity. We show that the {\sl explodability} of these stars, i.e., which of a neutron star (NS) or a black hole (BH) is formed, is sensitive to the strength of convective shell burning of C and O, and thus the mass fractions of C ($X$(C)) and O in the shell. For the small $^{12}$C($α, γ$)$^{16}$O reaction rate that yields larger $X$(C), $X$(C) is further enhanced by mixing of C from the overlying layer and then C shell burning is strengthened. The extra heating by C shell burning tends to prevent the contraction of outer layers and decrease the {\sl compactness parameter} at $M_r$ = 2.5 M$_\odot$. This effect leads to the formation of smaller mass cores of Si and Fe and steeper density and pressure gradients at the O burning shell in the presupernova models. If the pressure gradient there is steeper, the model is more likely to explode to form a NS rather than a BH. We describe the pressure gradient against $M_r$ with $V/U$ and the density drop with $1/U$, where $U$ and $V$ are non-dimensional variables to describe the stellar structure. We estimate the critical values of $V/U$ and $1/U$ at the O-burning shell above which the model is more likely to explode. We conclude that the smaller $^{12}$C($α, γ$)$^{16}$O reaction rate makes the mass range of $M ({\rm ZAMS})$ that forms a NS larger. |
| title | The Impact of $^{12}$C($α, γ$)$^{16}$O Reaction on the Presupernova Evolution and Supernova Explodability of Massive Stars |
| topic | Solar and Stellar Astrophysics Astrophysics of Galaxies High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2502.11012 |