基于$\varepsilon$机制的III星振动不稳定性的完全非绝热分析
Fully Nonadiabatic Analysis of Vibrational Instability of Population III Stars due to the $\varepsilon$-Mechanism
摘要：
对星族III主序星的振动稳定性进行了线性非绝热分析。研究表明，在具有$M \gtrsim 5\Mo$的大质量恒星中，氦燃烧（三重α反应）在主序星阶段开始，并产生$^{12}{\rm C}$，导致一部分Hoc循环的激活。结果发现，尽管如此，这些恒星与$M\lesssim 13\Mo$成为不稳定的偶极子g $_1$ -和g $_2$ -模式，由于$\varepsilon$ -机制，在早期的演化阶段，在pp-链仍然是占主导地位的核能源。由于$\varepsilon$ -机制的不稳定性发生在偏离中心的$^3$ He积累壳层的内部深处，对g-模式具有很大的振幅，并且增长时间比演化时间尺度短得多。因此，这种不稳定性可能会导致恒星内部的混合，并对这些恒星的演化产生重大影响。
英文摘要：
A linear nonadiabatic analysis of the vibrational stability of population III main-sequence stars was carried out. It was demonstrated that, in the case of massive stars with $M \gtrsim 5\Mo$, helium burning (triple alpha reaction) starts during the main-sequence stage and produces $^{12}{\rm C}$, leading to the activation of a part of the CNO-cycle. It was found that, despite of that, those stars with $M\lesssim 13\Mo$ become unstable against the dipole g$_1$- and g$_2$-modes due to the $\varepsilon$-mechanism, during the early evolutionary phase at which the pp-chain is still the dominant nuclear energy source. The instability due to the $\varepsilon$-mechanism occurs against g-modes having a large amplitude in the off-centered $^3$He accumulation shell in the deep interior, and the growth time is much shorter than the evolutionary timescale. This instability is therefore likely to induce mixing in the stellar interior, and have a significant influence on the evolution of these stars.
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