湍流应力对AGB星结构与演化的影响

The Influence of Turbulent Stress to Structure and Evolution of AGB Star

在混合程对流理论的基础上建立起考虑湍流应力作用的恒星结构与演化模型,并计算了8M⊙.研究表明,湍流应力对AGB星的演化有重要的影响,它使AGB星氦壳层热核反应更加不稳定,热脉动的发生大大提前而且更加频繁.这种热脉动的提前发生不仅使氦壳层内的光度、产能率、温度发生变化,同时使氢壳层内的各物理量和恒星表面的光度都同步发生改变.另外,湍流应力还使对流的混合作用加强,从而导致恒星内部及表面的各元素丰度都发生改变.

Based on the mixing-length theory of convection, this paper establishes the mold of stellar structure and studies the evolution of star with 8M⊙ from H-burning stages to the AGB stages considering the turbulences. The result indicates that the turbulences have tremendous influence on the stellar structure and the evolution of AGB star. On one hand, turbulences cause the thermonuclear reaction of the H-burning shell in AGB star to be unstable, and the occurrence of the thermal pulse greatly beforehand, and very frequent. Not only that this thermal pulse occurs beforehand, change the temperature, nuclear energy production and density in the H-burning shell, but also change the stellar surface luminosity at the same time. On the other hand, the turbulences make the mixing action of convection to strengthen.