转动恒星中的元素扩散效应研究

Investigation of diffusion of chemical elements in rotating stars

计算了影响元素扩散过程快慢的3个系数Deff,Dshear和Dh,根据转动恒星中的角动量传输和元素扩散方程,给出了转动恒星中的元素扩散效应.结果表明:子午环流是大质量恒星角动量转移的主要物理机制,而剪切湍流是传输化学元素的主要机制.增加水平湍流将增加子午环流和剪切湍流传输化学元素的效率.元素扩散效应造成恒星表面有4He和14N元素的超丰和较大的对流核心,使恒星具有较高的光度和较低的中心温度,对恒星结构与演化有极其重要的影响.

Three diffusion coefficients which can affect the diffusion process are calculated. The effects of the chemical elements mixing are given according to the diffusion equation of the chemical elements. It is shown that meridional circulation is the main driving mechanism for the transport of angular momentum while shear turbulence is the main driving mechanism for the transport of chemical elements. The larger horizontal turbulence tends to in- crease diffusion efficiency of meridional circulation and shear turbulence. The diffusion effect favours the transporta- tion of helium and nitrogen to the surface of rotating stars and a large convective core. The diffusion of the chemical element can make the star to have a higher luminosities and a lower temperature in the center of the star and have an important effect on the structure and evolutinn of the star.