DA型脉动变星的星震学研究

发布时间：2018-10-23 10:54

【摘要】：首先,本文对白矮星、脉动白矮星做了简要介绍,对恒星振动理论、白矮星星震学、白矮星演化程序及恒星振动程序做了简要介绍。然后,以三颗DA型脉动白矮星即G29-38,HS0507+0434B,和EC14012-1446为目标,分别做了星震学模型拟合并将结果与光谱结果进行比对。最后,在未来工作中介绍了欲将星震学工作和光谱工作结合起来,考虑拟合吸收线和连续谱的差别,希望获得对DA型脉动白矮星GD154的更可靠的拟合结果。2008年,Thompson等人根据不同球谐度的几何效应对光谱产生的临边昏暗效应对G29-38认证了11个脉动模式的球谐度数值。我们用WDEC做网格模型,取碳、氦和氦、氢扩散平衡轮廓,核中心20%核表面60%的线性碳丰度,拟合这11个振动模式,最终获得了最佳拟合模型。其中有效温度和重力加速度和许Pr艺等人2014年的光谱结果相符和其他人的光谱结果有出入。2013年,北京师范大学付建宁等人公布了他们对HS0507+0434B的WET联测结果。其中,6个等间隔三分裂的模式被认证成为l=1。我们使用WDEC构建网格模型,表面还是扩散平衡的轮廓,中心核尝试着线性拟合MESA生成的热核燃烧的碳轮廓。拟合这6个模式,我们的最佳拟合模型结果和Fontaine等人2003年的光谱结果以及Koester等人2009年的光谱结果很接近,但是和Gianninas等人2011年的光谱结果相差较大。将Handler等人2008年认证的独立本征频率和Provencal等人2012年认证的独立本征频率合起来考虑,我们重新对EC14012-1446做了模式认证。根据频率分裂关系和等周期间隔关系,我们认证了6个l=1,4个l=2,5个l=3,和10个l=1或2的模式。网格模型还是MESA的核加WDEC的壳,但是我们对MESA生成的白矮星质量和WDEC所需的白矮星质量做了匹配,并且在WDEC演化白矮星过程中考虑了元素扩散,并非直接取扩散平衡轮廓。最终星震学结果稍大于光谱结果。可靠的模式认证工作和符合物理条件的白矮星模型是白矮星星震学的必要条件。将星震学工作和光谱工作结合起来研究白矮星是一种有效的可行的研究方法。
[Abstract]:Firstly, the white dwarf and pulsating white dwarf are briefly introduced, and the theory of star vibration, the seismology of white dwarf, the evolution program of white dwarf and the program of star vibration are introduced briefly. Then, three DA pulsating white dwarfs, namely G29-38, HS0507 0434B, and EC14012-1446 are taken as targets. Finally, in the future work, it is introduced that we want to combine the astroseismological work with the spectral work, and consider the difference between the fitting absorption line and the continuous spectrum. In 2008, Thompson et al verified the spherical harmonic values of 11 pulsating modes on G29-38 according to the near edge dimming effect of different spherical harmonics on the spectrum. Using WDEC as the grid model, the equilibrium profile of carbon, helium, helium and hydrogen diffusion is taken, and the 60% linear carbon abundance on the core surface of the nuclear center is obtained. The 11 vibration modes are fitted and the best fitting model is obtained. The effective temperature and acceleration of gravity agree with those of others in 2014. In 2013, Fu Jianning and others published their WET results on HS0507 0434B. Of these, six equal-spaced three-splitting patterns were authenticated as lc1. We use WDEC to construct a grid model, the surface is still the contour of diffusion equilibrium, and the central core is trying to fit the carbon profile of hot core combustion generated by MESA linearly. By fitting these six models, the results of our best fitting model are very close to those of Fontaine et al. 2003 and Koester et al. 2009, but they differ greatly from those of Gianninas et al in 2011. Considering the independent eigenfrequency certified by Handler et al in 2008 and the independent eigenfrequency certified by Provencal et al in 2012, we remodel EC14012-1446. According to the frequency splitting relation and the equal periodic interval relationship, we have authenticated the models of 6 lg1, 4 LU 2, 5 LU 3, and 10 LU 1 or 2. The mesh model is also the kernel of MESA and the shell of WDEC, but we match the mass of white dwarf produced by MESA with the mass of white dwarf required by WDEC, and consider element diffusion in the process of WDEC evolution, not take diffusion equilibrium profile directly. The final astroseismological results are slightly larger than the spectral results. Reliable model verification and white dwarf model are necessary conditions of white dwarf seismology. It is an effective and feasible method to study white dwarf star by combining astroseismology and spectral work.
【学位授予单位】：中国科学院研究生院(云南天文台)
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P145.2

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