红外偏振对星际尘埃模型的限制

发布时间：2018-03-21 00:27

本文选题：偏振—尘埃　切入点：消光—近红外　出处：《湘潭大学》2015年硕士论文　论文类型：学位论文

【摘要】：星际尘埃通常是由非晶态硅酸盐和某种形式的含碳物质构成。但是某种形式的含碳物质中的成分是不清楚的。尘埃模型假设硅酸盐和碳尘埃在物理上形成壳层结构,或者他们结块形成多孔复合尘埃。核幔模型假设壳层是由某种脂肪族烃物质构成。当前,有三个经典的尘埃模型:硅酸盐-石墨-PAHs、硅酸盐核-碳氢壳(silicate core-carbon mantle)、复合疏松(composite)模型。在星际空间,硅酸盐尘埃因为硅原子-氧原子(Si-O)的振动,产生一个很强的吸收光谱,波长为9.7微米。在星际空间也观测到9.7微米的偏振,这说明硅酸盐尘埃的形状肯定不是球形。碳氢尘埃因为碳原子-氢原子(C-H)的振动,产生一个吸收光谱,波长为3.4微米。但是,在星际空间并没有观测到3.4微米的偏振.这就意味着,core-mantle模型是不是错了?从理论上分析,在何种情况下,coremantle尘埃模型,能产生9.7微米偏振,但不能产生3.4微米偏振。一个简单的想法是,硅酸盐核core是非球形,而碳氢壳层mantle是球形。但我们的计算表明,这种情况下,还是会产生3.4微米偏振。
[Abstract]:Interstellar dust is usually made up of amorphous silicate and some form of carbon-bearing material, but the composition of some form of carbon-bearing material is unclear. The dust model assumes that silicate and carbon dust physically form a shell structure. Or they caking to form porous composite dust. The core-mantle model assumes that the shell is made up of some aliphatic hydrocarbon. There are three classic dust models: silicate-graphite-PAHs, silicate-core-silicone core-carbon mantleer, composite loose composite. in interstellar space, silicate dust produces a strong absorption spectrum because of the vibration of silicon atoms-oxygen atoms. The wavelength is 9.7 microns. The polarization of 9.7 microns is also observed in interstellar space, indicating that the shape of the silicate dust is definitely not spherical. The hydrocarbon dust produces an absorption spectrum because of the vibration of the carbon atom-hydrogen atom C-H. The wavelength is 3.4 microns. However, no 3.4 micron polarization is observed in interstellar space. Does this mean that the core-mantle model is wrong? Theoretically, under what conditions can the coremantle dust model produce 9.7 micron polarization, but not 3.4 micron polarization. One simple idea is that the silicate core core is non-spherical, while the hydrocarbon shell mantle is spherical. In this case, 3.4 micron polarization will occur.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P155

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