The stability of massive main-sequence stars as a function of metallicity
The stability of massive main-sequence stars as a function of metallicity
复制标题
大质量主序星的稳定性与金属丰度的关系
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
P. Arras
中科院分区：
文献类型：
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作者：
J. Shiode;E. Quataert;P. Arras
我们研究了一系列金属丰度的大质量（M 120 M�）主序星的脉动稳定性，包括原始的第三星族星。我们包括一个配方的对流阻尼激励对流和周期性剪切流之间的相互作用的数值模拟。我们发现，对流粘性可能足够强，以稳定径向脉动时，核燃烧（的机制）是主要的驱动源。这表明Z 2 × 10 −3的大质量主序星是脉动稳定的，不太可能在主序星上经历脉动驱动的质量损失。然而，这些结论是敏感的对流粘性的形式，并强调需要进一步的高分辨率模拟的对流振荡相互作用。对于更多金属含量的恒星（Z 2 × 10 −3），主要的脉动驱动是由不透明度中的铁凸块产生的κ机制引起的，并且足够强以克服对流阻尼。我们的研究结果强调，即使是振荡周期短于外对流周转时间的几个数量级，对流-振荡相互作用的“冻结”近似是不合适的，对流阻尼应考虑评估模式稳定性时。
We investigate the pulsational stability of massive (M 120 M� ) main-sequence stars of a range of metallicities, including primordial, Population III stars. We include a formulation of convective damping motivated by numerical simulations of the interaction between convection and periodic shear flows. We find that convective viscosity is likely strong enough to stabilize radial pulsations whenever nuclear burning (the � -mechanism) is the dominant source of driving. This suggests that massive main-sequence stars with Z 2 × 10 −3 are pulsationally stable and are unlikely to experience pulsation-driven mass loss on the main sequence. These conclusions are, however, sensitive to the form of the convective viscosity and highlight the need for further high-resolution simulations of the convection–oscillation interaction. For more metal-rich stars (Z 2 × 10 −3 ), the dominant pulsational driving arises due to the κ-mechanism arising from the iron-bump in opacity and is strong enough to overcome convective damping. Our results highlight that even for oscillations with periods a few orders of magnitude shorter than the outer convective turnover time, the ‘frozen-in’ approximation for the convection–oscillation interaction is inappropriate, and convective damping should be taken into account when assessing mode stability.