星震学校准的内部混合对大质量恒星核合成星风产量的影响
The impact of asteroseismically calibrated internal mixing on nucleosynthetic wind yields of massive stars
AI总结：
本研究基于星震学校准的内部混合参数，探讨了其对20太阳质量恒星演化结构与核合成星风产量的影响，发现星震混合水平显著改变星风产量及碳燃烧过渡时机。
摘要：
星震学使我们有机会窥探恒星内部并确定其内部性质。基于这些观测，可以估算此类恒星的对流边界混合和包层混合的量，以及包层中混合剖面的形状。然而，这些结果通常未被包含在恒星演化模型中。我们旨在研究基于星震学建模范围内的对流边界混合和包层混合在恒星模型中的影响，包括对恒星结构和核合成产量的影响。在这项初步研究中，我们关注一颗20太阳质量恒星的爆炸前演化，并将模型演化到碳燃烧的最后阶段。我们改变对流边界混合（以阶梯式超射实现），超射参数范围为0.05-0.4，包层混合量范围为1-10^6，并采用基于内部重力波的混合剖面。我们使用包含212种同位素的大型核网络来研究核合成。我们发现，根据主序星星震学增强的混合（无论是在对流核心边界还是在包层中）对核合成星风产量有显著影响。我们超出主序的演化模型在产量上与基于旋转混合的模型存在差异，具有更长的氦燃烧寿命和更轻的氦耗尽核心。我们发现，从核心氢燃烧恒星校准的内部混合星震范围产生的星风产量与旋转混合理论产生的结果相似。在主序之后采用星震混合水平，我们发现与基于旋转混合的模型相比，更早地过渡到辐射碳燃烧。这影响了致密度和壳层合并的发生，可能影响超新星性质和爆炸核合成。
英文摘要：
Asteroseismology gives us the opportunity to look inside stars and determine their internal properties. Based on these observations, estimations can be made for the amount of the convective boundary mixing and envelope mixing of such stars, and the shape of the mixing profile in the envelope. However, these results are not typically included in stellar evolution models. We aim to investigate the impact of varying convective boundary mixing and envelope mixing in a range based on asteroseismic modelling in stellar models, both for the stellar structure and for the nucleosynthetic yields. In this first study, we focus on the pre-explosive evolution of a 20Msun star and evolve the models to the final phases of carbon burning. We vary the convective boundary mixing, implemented as step-overshoot, with the overshoot parameter in the range 0.05-0.4 and the amount of envelope mixing in the range 1-10$^{6}$ with a mixing profile based on internal gravity waves. We use a large nuclear network of 212 isotopes to study the nucleosynthesis. We find that enhanced mixing according to asteroseismology of main-sequence stars, both at the convective core boundary and in the envelope, has significant effects on the nucleosynthetic wind yields. Our evolutionary models beyond the main sequence diverge in yields from models based on rotational mixing, having longer helium burning lifetimes and lighter helium-depleted cores. We find that the asteroseismic ranges of internal mixing calibrated from core hydrogen burning stars lead to similar wind yields as those resulting from the theory of rotational mixing. Adopting the seismic mixing levels beyond the main sequence, we find earlier transitions to radiative carbon burning compared to models based on rotational mixing. This influences the compactness and the occurrence of shell-mergers, which may affect the supernova properties and explosive nucleosynthesis.
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