II型超新星爆发过程中的丰度梯度和压强梯度

发布时间：2018-02-24 07:25

  本文关键词： 超新星 丰度梯度 压强梯度 爆发能量　出处：《广西师范大学》2010年硕士论文　论文类型：学位论文

【摘要】： 在核心坍缩型超新星爆发机制的数值模拟中,能量问题一直是导致超新星爆发不能成功的主要原因,但是超新星爆发的巨大能量是得到了大量观测和实验支持的。如果考虑它的引力势能作为爆发的主要能量,在原有的计算方法下会发现释放的总的引力势能很有限,而中微子泄漏以及铁星核光裂解消耗大量的能量都是必须的。为了解决这个困难,Baron和Coopemtein提出了调节引力常数的方法,王贻仁等提出了“等效厚度”的假设。而本文则根据罗志全等人提出的有关压强梯度影响Ⅱ型超新星爆发的相关理论,在有限的引力能释放的情况下,通过丰度梯度和压强梯度的修改来提高激波能量,使得瞬时强爆炸能够成功。丰度梯度和压强梯度过去一直没有引起人们的足够重视,但是本文发现它与超新星瞬时爆发能量有着十分密切的关系。利用Woosley等人得出的前身星模型数据和王贻仁小组开发的Ⅱ型超新星爆发模拟程序“SNⅡ-WLYW89”,模拟了质量为11M⊙、12M⊙、13M⊙、14M⊙、15M⊙的五个超新星爆发过程。 数值结果表明,在坍缩阶段,适当修改元素丰度梯度和压强梯度,激波能量能够传到铁核边缘。当重核丰度梯度,中子丰度梯度,质子丰度梯度,α粒子丰度梯度的改变量β都取1.03时,除模型S11、S15的爆发能稍有降低外,其它三个模型的爆发能都增大了;当总的元素丰度梯度的改变量β取0.90,α,n和p混合压强梯度,辐射压强梯度,中微子压强梯度的改变量β都取1.02时,五个模型的爆发能都有不同程度的提高;当总的压强梯度的改变量β取1.05时,除S15的激波能量不能转到铁星核边缘,其它四个模型的爆发能都提高了;当重核丰度梯度,中子丰度梯度,质子丰度梯度,α粒子丰度梯度的改变量β都取1.03 ,总的元素丰度梯度的改变量β都取1.03,重核物质压强梯度,α,n和p混合压强梯度,辐射压强梯度,中微子压强梯度的改变量β都取1.02,总的压强梯度的改变量β取1.05时,元素丰度梯度的改变并没有改变爆发时间,而压强梯度的改变使得爆发时间延长了。修改总的元素丰度梯度后,熵增大了,而物质温度在t3 , t 4时刻有所降低,在其它时刻变化不明显。通过数值模拟可见,在有限的引力能量释放的情况下,丰度梯度和压强梯度的调整增强了对流传能机制,提高了爆发能量,使得瞬时强爆炸能够成功。
[Abstract]:In the numerical simulation of the mechanism of the core collapse supernova explosion, the energy problem has been the main reason for the failure of the supernova explosion. But the great energy of the supernova burst is supported by a lot of observations and experiments. If the gravitational potential energy is considered as the main energy of the explosion, the total gravitational potential energy released under the original calculation method will be very limited. However, neutrino leakage and photocracking of iron star nuclei are necessary. In order to solve this problem, Baron and Coopemtein proposed a method to adjust the gravitational constant. Wang Yi-ren and others put forward the hypothesis of "equivalent thickness". In this paper, according to the theory of pressure gradient affecting the explosion of type II supernova proposed by Luo Zhiquan and others, under the condition of limited gravitational energy release, By modifying the abundance gradient and the pressure gradient to increase the shock energy and make the instantaneous strong explosion succeed, the abundance gradient and the pressure gradient have not been paid enough attention to in the past. However, it is found that it is closely related to the instantaneous burst energy of supernova. Using the former star model data obtained by Woosley et al and the simulation program "SN 鈪，

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