恒星内部的超声速对流区

Supersonic Convection in the Stellar Interiors

依传统的局部混合长理论进行了对流包层模型计算,在黄红巨星和超巨星对流区的顶部出现超声速对流的情况,这与局部对流理论本身是不自恰的．文章详细分析了恒星大气超声速对流的成因,并按照星族Ⅰ恒星的演化轨迹,在赫罗图上给出了出现超声速对流的区域．其结果是。在演化过程中, (1)低质量星基本不出现超声速对流; (2)中等质量星的超声速对流主要出现在3．6<lgTe<4的区域,且从左下往右上倾斜,超声速对流出现在氢的电离区．对质量稍大的星,超声速对流区域延伸到红巨星部分; (3)大质量星在脱离主序后不久便进入超声速对流区,越大质量的星发生超声速对流的年龄越早．对蓝超巨星,超声速对流出现在lgT-5．3(铁的吸收峰)和氮的二次电离区,而红、黄巨星和超巨星,超声速对流出现在氢的电离区．

According to the result of the numerical simulation of the traditional mixlength theory, supersonic convection would occur on the top of convective regions of both the yellow-and-red giants and super giants. This, however, is not self-consistent with the local convection theory. Therefore, this paper is devoted to analyze in full detail what has caused the formation of supersonic convection, and at the same time to present a plot of the supersonic convective region on the H-R diagram based on the evolutionary tracks of population Ⅰ stars. The main results of this paper are as follows： during the process of evolution, （1） no supersonic convection occurs in low mass star; （2） for the intermediate mass stars, supersonic convection chiefly occurs in the region of 3.6 〈 lg Te 〈 4.0 on the H-R diagram, tilting from lower left to upper right and extending to the region of red giants, supersonic convection occurs owing to the onset of hydrogen ionization; （3）supersonic convection immediately occurs after a typical massive star deviates from ZAMS, the heavier the star is, the earlier the phenomena emerges. In addition, both He and metallic elements play important roles in determining the occurrence of supersonic convections in massive stars. For blue supergiants, supersonic convection occurs owing to the onsets of secondary ionization of He and absorbing peak（lg T ～ 5.3） of lee. But for red- and yellow-giants and supergiants, it does owing to the onset of hydrogen ionization.