2025/02/16 by Wenyu Xin, K. Nomoto, Xin, Wenyu +3
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE) #Nuclear physics research studies #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2502.11012
openalex publication_date 2025/02/16 · openalex created_date 2025/02/19 · openalex updated_date 2026/07/28
Among the uncertainties of stellar evolution theory, we investigate how the 12C(α, γ)16O 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 12C(α, γ)16O 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 Mr = 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 Mr 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 12C(α, γ)16O reaction rate makes the mass range of M (\rm ZAMS) that forms a NS larger.