【作者】 龚景；

【导师】 李爱根；

【作者基本信息】 湖南师范大学 ， 天体物理， 2008， 硕士

【摘要】 近年来,随着宇宙学研究的不断深入,人们热切希望能够精确地测定宇宙参数（H₀,Ω_Μ,Ω_Λ等）,从而能够判断宇宙的最终命运。然而对于宇宙尺度的距离测定是不得不首先解决却很难解决的问题。幸运的是,一种特别的天体--超新星为我们提供了一个很好的距离定标器.这是因为它具有以下两个特征:（1）I_a超新星非常亮,一颗典型的I_a超新星爆发时产生的光度通常可达到星系的量级,是造父变星的10⁶倍;（2）I_a超新星的峰值光度同光变曲线形状相关。通过相应的校正可导出超新星的本征峰值光度,其误差在11%以内。1998和1999年,两个独立的高红移超新星观测研究小组根据他们的超新星观测数据发现这些超新星的实际距离要比由标准宇宙模型（Ω_Μ=0.2,Ω_Λ=0）计算出的理论值乎均远10-15%,因此他们得出了(Ω_Λ≠0,q₀（减速因子）＜0即宇宙正在加速膨胀的结论。然而,我们知道尘埃在宇宙中是无处不在的,它的消光作用使得通过它的星光暗淡下来,也就使得该天体看起来远一些。本文根据已有的尘埃理论知识以及已知的关于尘埃的观察现象,推论出尘埃的一些基本特征。并在遵守如下两个原则的基础上得出了尘埃的基本模型:（1）目前宇宙中的恒星诞生率;（2）尘埃颗粒的物理性质。这种尘埃模型不同于普通的尘埃颗粒,它不会产生明显的红化现象,同时却仍然有很强的消光。因此它的形状也不是普通的球形,而是类似于针状。正因为这种特性,它的消光就不能通过多色光变曲线法消除。而本文通过光谱分析,得到了尘埃的消光和散射特征及其光谱型,并在某些近似条件下推导出了尘埃的消光公式。更多还原

【Abstract】 Rencently,with the profound study of cosmology,it is hope to accurately measure the cosmological parameters（H₀,Ω_M,Ω_Λetc.）,estimate the ultimate fate of universe.However, the measurament of the distance is the first but difficult problem to solve.Fortunately,a kind of special celestial body--supernova,provides us a good distance scaler.This is due to the following two characteristics of supernova:firstly,it is very bright,the luminosity from the explosion of a typical supernova can achieves that of a glaxy,10⁶ times that of cepheid variable.Secondly,the peak luminosity of Ia supernova is associated with the light curve.The absolute peak luminosity of supernova can be deduced from corresponding correction,with the error within 11%.In 1998 and 1999,two seperate high-redshift supernova research group found that the mean actual distance of the supernovas is 10 - 15%further than the theoretical value that cauculated by standerd cosmological model,basing on their observation data,so they obtainedΩ_Λ≠0,q₀（deceleration parameter）< 0,which means the accelerate expanding of universe.However,we know that the dust is everywhere in the universe,it’s extinction makes the light through by obscured,so that star appears further.In this paper,we deduce some basic characteristics of dust,according to the current dust theory and some phenominon of dust.We obtain the basic dust model,on the basis of two priciples:at first,the birth probability of stars,in current universe.Second,the physical properties of dust particles.This dust model is different from ordinary dust particles,though it doesn’t contain apparent phenominon of redden,it still has effect of strong extinction.So its shape is not of ordinary shpere,but needle-like.Because of this charateristic,its extinction can’t be eliminated by multicolor light curve shape method.In this paper,we obtain the extinction and scattering charateristics as well as the spectral type of dust,and deduce for dust the extinction formular with some approximated condition.更多还原