基于样条函数的恒星光谱自动归一化方法  

Automatic Normalization Method of Stellar Spectrum Based on Spline Function

作　　者：罗锋 刘超[1,2] 赵永恒 Luo Feng;Liu Chao;Zhao Yongheng(National Astronomical Observatories. Chinese Academy of Sciences. Beijing 100101. China. Email;University of Chinese Academy of Sciences. Beijing 100049. China)

机构地区：[1]中国科学院国家天文台,北京100101 [2]中国科学院大学,北京100049

出　　处：《天文研究与技术》2019年第3期300-311,共12页Astronomical Research & Technology

基　　金：国家自然科学基金(11873057)资助

摘　　要：恒星的观测谱一般由连续谱、谱线和噪声组成,其中连续谱是黑体辐射导致的辐射流量随波长变化的光滑连续光谱。光谱分类及恒星物理参数估计等研究依赖于连续谱及谱线信息的准确提取。因此光谱数据处理的工作主要是拟合连续谱,并通过对光谱进行归一化来提取谱线特征。连续谱拟合的方法主要有多项式拟合、中值滤波、小波滤波等。已有的方法在低信噪比、宇宙线信号干扰、存在发射线等情况下,有不同程度的局限性,体现在鲁棒性和准确度上。目前,针对郭守敬望远镜的10 7条光谱没有自动化方法应用到归一化上的问题,研究并开发一种适用于不同的温度、信噪比及波长覆盖范围,并能够自动化处理的恒星光谱归一化方法,显得十分迫切。在仔细分析不同类型光谱的基础上,提出了一种基于固定窗口划分的连续谱拟合方法。该方法对光谱中能够体现连续谱特征的数据点进行筛选提取,通过细微地控制样条函数平滑度产生更加准确的连续谱。使用郭守敬望远镜中不同光谱型、温度范围、波长覆盖范围的光谱进行实验,结果表明,该方法具有良好的精度和普适性。The observed spectrum of stars is generally composed of continuous spectrum,spectral line and noise.The continuous spectrum is the smooth continuous spectrum of radiation flux varying with wavelength caused by blackbody radiation.Spectral classification and stellar physical parameter estimation depend on the accurate extraction of continuous spectrum and spectral line information.Therefore,the main work of spectral data processing is to fit continuous spectrum and extract spectral line features by normalization.At present,the methods of continuous spectrum fitting mainly include polynomial fitting,median filtering and wavelet filtering.Existing methods have limitations to varying degrees in the case of low SNR,interference of cosmic ray signals and existence of emission lines,which are mainly reflected in robustness and accuracy.For the time being,there is no automated method applying to the normalization of the 10 7 spectra from LAMOST.In the period of avalanche of astronomical data,it is very urgent to research and develop a spectral normalization algorithm of stars with better universality and automatic processing that can be applied to a wider range of temperature,SNR and wavelength coverage.On the basis of careful analysis of different types of spectra,a continuous spectrum fitting method based on fixed window dividing is proposed.This method can filter and extract the data points in the spectrum which can reflect the characteristics of continuous spectrum,and produce more accurate continuous spectrum by fine controlling the smoothness of spline function.Experiments are carried out using spectra of different spectral types,temperature ranges and wavelength coverage ranges in LAMOST,and the results show that the proposed algorithm has good accuracy and universality.

关 键 词：连续谱归一化 郭守敬望远镜 恒星光谱 样条函数 

分 类 号：TH751[机械工程—仪器科学与技术]