| 摘要 | 星震学是一门研究恒星振动的学科，人们可以利用星震学诊断的方法去了解恒星内部物理过程，例如恒星的核心结构，结构的突变以及旋转。在日震学取得重大成就后，随着观测水平的不断提高，加快了星震学的发展，它有助于我们精确测定恒星参数，探测恒星的内部结构，检验恒星内部的物理过程。现如今，星震学分析已然成为了研究恒星结构和演化的重要手段。本文的主要研究工作内容是利用星震学数据对类太阳恒星进行分析。研究数据基于Kepler卫星观测得到的振动数据，我们通过构建了恒星质量在0.9到1.4倍太阳质量之间、初始氦丰度与金属丰度不同、并且有无混合扩散过程的模型网格，计算了所有的振动频率，利用Hermite三次多项式在恒星演化轨迹上对任意年龄的恒星P模式振动进行插值，总计研究了16颗类太阳恒星，通过模型频率与观测频率的比较，得到了恒星参数的建议范围以及全局变量，另外通过有无混合扩散的过程展开对模型构建的准确性的讨论，并分析了扩散对恒星演化的影响。研究结果表明，当恒星参数在建议的范围内时，模型频率可以很好地拟合观测结果。每颗恒星的最佳模型对应𝜒2值最低，通过分析𝜒2对全局变量们的依赖性，得到了恒星参数（M、Zini、Yini）和一些重要的全局变量(Teff,R,t,Xc, Rbc/R)的建议范围。最后，我们还分析了𝜒2对Yini的依赖性。文中研究了分子扩散对恒星演化中初始丰度的影响，不考虑扩散时，模拟显示所有目标星的初始氦丰度均低于原初核合成(Big Bang Nucleosynthesis, BBN)的初始氦丰度YP，有扩散的影响时，对于所有的目标星，初始氦丰度Yini普遍增高且高于BBN的初始氦丰度YP，而且𝜒2的最小值也随之降低。同时我们分析了频率二阶差分的影响，结果显示有扩散影响下模型频率的二阶差分有明显的振动分量。因此我们认为，分子扩散在模拟类太阳星演化中是至关重要的，可以有效的避免Yini与BBN初始氦丰度冲突的问题。 |
| 其他摘要 | Asteroseismology is the study of stellar oscillations. People can use the diagnosis method of asteroseismology to understand the internal physical processes of stars, such as the core structure of stars, structural changes and rotation. After the great achievements of helioseismology, with the continuous improvement of the observation level, the development of asteroseismology has been accelerated. It helps us to accurately measure the parameters of stars, probe the internal structure of stars, and check the physical processes inside stars. Nowadays, Asteroseismological analysis has become an important means to study the structure and evolution of stars. The main research content of this paper is the analysis of solar-like stars using asteroseismological data. The research data is based on the vibration data obtained from the kepler satellite. By constructing a model grid of star masses ranging from 0.9 to 1.4 solar masses, different initial helium abundance and metal abundance, and whether there is mixed diffusion process, we calculate all vibration frequencies. Using Hermite cubic polynomial to interpolate the p-mode vibration of stars of any age on the stellar evolution trajectory, a total of 16 solar-like stars were studied. By comparing the model frequency with the observed frequency, the suggested range of stellar parameters and all global variables were obtained. In addition, the accuracy of the model construction was discussed through the process of whether there was mixing diffusion or not.The results show that the model frequency can fit the observations well when the stellar parameters are within the suggested range. The best model of each star has a low 𝜒2 value on the unit scale. By analyzing the dependence of 𝜒2 on global variable, Got stars parameters (M and Zini, Yini) and some important global variable (Teff, R, t, Xc, Rbc/R) advice. Finally, we also analyzed the 𝜒2 to Yini dependence. The effect of molecular diffusion on the initial abundance of stellar evolution is studied in this paper. Without considering the diffusion, the simulation shows that the initial helium abundance of all target stars is lower than that of the Big Bang Nucleosynthesis (BBN). For all target stars, The initial helium abundance Yini is generally higher than the initial helium abundance YP of BBN, and the minimum value of 𝜒2 also decreases. At the same time, we analyze the influence of second-order difference of frequency, and the results show that the second-order difference of model frequency has obvious vibration component under the influence of diffusion. Therefore, we believe that molecular diffusion is very important in simulating the evolution of solar-like stars, which can effectively avoid the conflict between Yini and the initial helium abundance of BBN. |
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