14倍太阳质量核心坍缩超新星前身星演化末期完整硅壳燃烧阶段的三维模拟
3D simulations of a complete convective silicon shell burning phase
中文总结 AI 辅助
本研究通过三维流体动力学模拟探究14倍太阳质量超新星前身星硅壳燃烧阶段，发现三维模拟因对流边界混合程度低使硅壳燃烧缩短约800秒，该过程为对流-反应事件，需更完整核网络开展后续研究。
中文摘要 AI 辅助
我们采用简化的25同位素核网络，对14倍太阳质量核心坍缩超新星前身星演化末期直至燃料耗尽的完整硅壳燃烧阶段开展了三维流体动力学模拟。研究了真实湍流对流如何影响该燃烧阶段，该阶段的核反应体系比此前的燃烧阶段更为复杂。我们发现三维模拟与一维的MESA模型存在广泛相似性，但由于流体动力学模拟中极刚性的对流边界提供了更真实的反馈，三维模拟的对流边界混合（CMB）程度低于一维模型，因此较少新鲜燃料被卷入硅壳，这导致三维模型中的硅壳燃烧时长缩短了约800秒。我们发现主导反应的核燃烧时标快于混合时标，使整个过程成为对流-反应事件。角平均能量生成剖面呈现双峰结构，正峰之间的区域接近零或为负。我们发现在硅壳底部，许多（α,p）反应及其逆反应至关重要，正逆反应速率极为相似，因此温度的微小波动会使区域呈现放热或吸热状态，导致能量生成演化过程复杂。本研究采用单一简化核网络进行了探索，但由于该燃烧阶段的敏感性，未来研究应探究更完整核网络的影响。
英文摘要
We present 3D hydrodynamic simulations of a complete silicon shell burning phase until fuel exhaustion at the end of the evolution of a 14$M_\odot$ core-collapse supernova progenitor, using a reduced 25-isotope nuclear network. We investigate how realistic turbulent convection affects this burning phase, which has a more complicated set of nuclear reactions than previous burning phases. We find broad similarities between the 3D simulation and the 1D \textsc{MESA} model. However, due to more realistic feedback from the very stiff convective boundaries in the hydrodynamic simulations, the 3D simulation experiences lower convective boundary mixing (CMB) compared to 1D, and hence entrains less fresh fuel into the silicon shell. This leads to the silicon shell in the 3D model burning for roughly 800\,s shorter. We find that the nuclear burning timescales for the dominant reactions are faster than the mixing timescale, making this entire process a convective-reactive event. The angular-averaged energy generation profile shows a double-peaked structure, where the region between the positive peaks are close to zero, or are negative. We find that throughout the base of this silicon shell, many $(α, p)$ and their inverse reactions are important. The forward and reverse rates are very similar, so slight fluctuations in the temperature cause regions to be either exoergic or endoergic, leading to a complicated energy generation evolution. This study presents an exploration using a single reduced nuclear network, however, due to the sensitivity of this burning phase future studies should investigate the impact of more complete nuclear networks.
