AGB星中子辐照量分布的特点

Characteristics of the Distribution of Neutron Exposures in Low-mass AGB Stars

根据13C辐射燃烧的低质量AGB(asymptotic giant branch)星s-过程核合成模型,考察氦壳层核合成区域中子辐照量分布(简称DNE)的特点.结果表明,辐射s-过程核合成模型的DNE,即ρAGB(τ),与重叠因子r、核合成区域的质量比q、每次中子照射的最大辐照量τmax和脉冲次数m等参数有关.增大各参量的值,都会使具有较大中子辐照量的种子核比例增加,但程度不同.r和m影响较小,q和τmax影响较大,且q与r值相差越多q的影响越显著.选择合适的模型参数,还可以给出太阳系的DNE.根据AGB星s-过程核合成数值计算的结果确定q,r,m的值,通过对多事件模型的结果进行最小二乘法拟合选择τmax的值,最后给出太阳系的DNE.

Based on the radiative s-process model for low-mass asymptotic giant branch（hereafter AGB） stars,an investigation on the characteristics of distribution of neutron exposures（hereafter DNE） in nucleosynthesis region is presented.The DNE in the He intershell,ρAGB（τ）,is calculated and the effects of model parameters on it are discussed.The results show that,their related to four parameters：the overlap factor,the mass fraction of pocket in the He intershell,ρAGB（τ）,the maximum of neutron exposure in the q layer and the thermal pulse number.The value of increases with the four parameters in varying degrees.It depends on and strongly,and and weakly.The DNE for the solar system is also given by the value of decided by fitting the calculating results to that from the canonical multi-event s-process model.