激变变星是一类特殊而且数量稀少的双星系统, 其主星是一颗白矮星, 伴星通常是一颗充满洛希瓣的光谱型为G, K或M型的晚型星或矮星。 激变变星是一类爆发型的恒星, 对于研究密近双星的演化具有积极的意义。 激变变星按照爆发特征和光变特征可以分为很多亚型, 如新星、 再发新星、 矮新星、 类新星和磁激变变星。 同时激变变星又是一类周期型的变星, 这些因素都导致其可见光光谱非常复杂。 目前对于激变变星的参数测量, 主要通过后续观测来测量其轨道周期、 主星和伴星之间的距离等。 由于在吸积的过程中, 物质在白矮星的表面累积, 无法直接测量主星的物理参数, 而且激变变星本身是一种暗弱的天体, 实测光谱数量较少, 因此极大限制了对激变变星物理参数的系统研究。 目前唯一能够生成激变变星理论光谱的软件是基于光致电离模型的CLOUDY, 但CLOUDY存在采样点过于稀少以及参数太多等问题, 不能作为理想的理论光谱模板。 法国ELODIE高分辨率的光谱可以作为M型恒星光谱参数测量的理论模板。 前期工作中, 通过机器学习等方法在美国斯隆巡天和中国郭守敬望远镜巡天数据中发现了一批激变变星。 通过人工筛选, 选择了伴星是M型的407条实测光谱, 这些光谱大部分是宁静期的矮新星, 光谱的主要特征是巴尔末线系和氦的发射线。 再通过与高分辨率的ELODIE光谱交叉, 利用SDSS-casjob数据库中的ELODIE参数, 对激变变星的红端部分进行模板匹配, 系统测量了其伴星的物理参数。 为了降低计算量, 对高维的光谱分别通过主分量分析和局部线性嵌入两种方法进行了特征提取和降维。 实验结果表明LLE方法在邻域大小15, 维度59时达到最高贡献率94.91%。 根据PCA和LLE的交集, 最终光谱的维度确定为59。 实验中发现激变变星的伴星中M2型数量极少, 具体原因需要更多的样本来解释。 因为实验中激变变星光谱中, 只有部分有明显的分子带特征, 因此那些在爆发下降阶段或者光谱被吸积盘特征控制的激变变星没有进行参数测量。 该实验弥补了激变变星光谱物理参数测量的空白。

Cataclysmic variable star is a kind of special and rare binary system, of which the primary star is a white dwarf and the companion is normally a G, K or M-type late star or dwarf. CVs usually have very large outbursts and have positive significance for the study of the evolution of close binary stars. According to the characteristics of explosion and light variation, CVs can be divided into many subtypes, such as nova, recurrent nova, nova-like stars, dwarf nova and magnetic CVs. As a periodic variable star, the spectra of CVs are very complex. At present, the parameter measurements of CVs focus on the distance and the orbital periodic etc. Since matter accumulates on the surface of a white dwarf during accretion, it is not possible to directly measure the physical parameters of the main star. What is more, CV is a kind of faint celestial body and the number of its spectra is limited. Therefore, the study of the physical parameters of the CVs is greatly restricted. The only software currently capable of generating the spectra of CVs is CLOUDY with a photoionization model. But the number of sampling points of CLOUDY is limited and there are too many parameters. The spectra produced by CLOUDY cannot be used as ideal theoretical template. The high resolution spectra of ELODIE in France can be used as a theoretical template for measuring the spectral parameters of M-type stars of CVs. In order to compensate the blank of the spectral parameter measurement of CVs, in this paper, spectra with parameters from ELODIE are used as template spectra and 407 SDSS CVs spectra detected by data mining method before are measured by template matching. Most of these spectra are in quiet state and the main characteristic of the spectra are emission lines of Barmer and Helium. In order to reduce the computation, the feature extraction and dimension reduction of high-dimensional spectra are carried out by principal component analysis and local linear embedding. The experimental result shows that the LLE method has a maximum contribution rate of 94.91% with the neighborhood size of 15 and the dimension number of 59. According to the intersection of PCA and LLE, the final dimension of the spectra was determined to be 59. In the experiment, it is found that the number of M2 type companion is limited, and more samples are needed to explain the specific resaons. Because only some of the experimental cataclysmic variable spectra have distinct molecular bands, the spectra in decline stage are ignored. The experiment in this thesis makes up the gap of measurement of physical parameters of the spectra of the CVs.