一种基于主分量分析的恒星光谱快速分类法

A PCA Based Efficient Stellar Spectra Classification Method

恒星光谱分类是天体光谱自动识别中的重要组成部分。本文主要介绍一种实用的基于主分量分析(PCA)法对恒星光谱进行快速自动的分类方法。该方法在恒星的主分量空间中对样本点进行投影 ,并利用最近邻分类器进行分类 ,获得与恒星MK分类标准的光谱型基本一致的结果。本文的主要工作有 :(1 )利用PCA方法构造恒星光谱的特征矩阵 ,建构恒星的主分量空间 ;(2 )对恒星光谱进行主分量投影 ,对投影点进行光谱型和光度级的分类器设计 ,利用最近邻法分类 ,最后得出恒星的分类树。该分类法速度快 ,分类准确率较高 ,对目前许多大型光谱巡天计划所获得的大量光谱数据的处理有着重要的意义。

Stellar spectra classification is an indispensable part of any workable automated recognition system of celestial bodies. This paper introduces an efficient method of automated classification of stellar spectra based on the principal component analysis (PCA). The method consists of two parts. In the first part, the eigen-matrix is built by a standard PCA technique where only the first two eigen-vectors are selected due to their predominance. More specifically, the first two eigenvalues are found to always represent more than 95% of the total sum of all the eigenvalues, and much larger than others in our all experiments. The principal component space of stellar (V-1, V-2) then is constructed from the first two eigenvectors. In the second part, namely classification part, an unknown spectrum X is first mapped to a 2D space with the two coordinates defined respectivey as ( V-1(T) X, V-2(T) X), then the nearest neighbor approach in this 2D space is employed to determine the spectral type as well as luminosity class of the input spectrum. The experimental results show that our new method can achieve comparable performance with that by the standard MK spectral types classification criterion, which is regarded as a benchmark in astronomy field. Thanks to its high efficiency, our new method appears promising especially for the processing of spectra in large quantities collected from large survey projects, such as LAMOST project in our country.