AGB星s-过程核合成区域中子辐照量分布  

Distribution of Neutron Exposures in the S-process Region of an AGB Star

作　　者：张凤华[1,2] 张波[2] 

机构地区：[1]沧州师范专科学校物理与电子信息系,沧州061001 [2]河北师范大学物理科学与信息工程学院,石家庄050016

出　　处：《天文研究与技术》2009年第2期92-99,共8页Astronomical Research & Technology

基　　金：国家自然科学基金(10673002)资助项目

摘　　要：介绍了AGB(Asymptotic Giant Branch)星s-过程核合成区域中子辐照量分布的最新研究结果。然后将不同AGB星s-过程核合成模型给出的太阳系中子辐照量分布与由观测约束得出的结果进行对比,分析论证了最新研究结果的可靠性。There are two main approaches to study the s-process： the first is to use the classical models and the second is through calculating the nueleosynthesis in AGB （Asymptotic Giant Branch ）stars with analytical models. For the old s-process models, the scenario of s-process in the convective zone can naturally lead to an exponential distribution of neutron exposures （hereafter ＂DNE＂ for the ＂distribution of neutron exposures＂）. The classical-model parameter τo （ mean neutron exposure） is related to the analytical-model parameters △τ（ the neutron exposure per pulse） and r （ overlap factor） by a simple equation： τo = -△τ/ln r. This suggests the agreement between the two approaches. However, for a present model following Gallino et al. （1998）, the DNE becomes very complex and can hardly be described analytically. Recent results show that the new analytical model still remains consistent with a classical model on the DNE, but the relation between τo and △τ- takes a different form. In this paper, we review the history and the current status of studies on the DNE values in the s-process regions in AGB stars. Particularly, the neutron exposures （previously received by the matter） in the solar system as predicted by different AGB star s-process models are compared to the observed data （ -constrained by the abundances of heavy elements）. The latest study results are subsequently analyzed and discussed for their reliabilities.

关 键 词：中子辐照量分布 AGB星 s-过程核合成 

分 类 号：P148[天文地球—天体物理]