激变变星光谱参数测量研究

doi:10.3964/j.issn.1000-0593(2019)09-2935-05

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Abstract 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.

Key words：Spectra; Parameter measurement; Cataclysmic variable stars

Received: 2018-07-06 Accepted: 2018-11-18

ZTFLH:

TP29

Corresponding Authors: QU Mei-xia E-mail: whkunyushan@163.com

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2019)09-2935-05 OR https://www.gpxygpfx.com/EN/Y2019/V39/I09/2935