| 其他摘要 | Cataclysmic Variable Stars (CVs) are interactive semi-contact binary systems, which consist of a filled (K/G/M-type) main sequence dwarf or giant and an evolved white dwarf. During the process that materials are transferred from main sequence dwarf to white dwarf, the material stream can not fall on the surface of white dwarf, but go round the white dwarf due to its large angular momentum, and extends to a disk because of viscosity and friction. When the new stream hits the disk, a hot area on the rim of disk can be produced with high luminosity - hot spot. Thus, a physical image for CVs can be constructed by the white dwarf, accretion disk, hot spot and red dwarf. Except for polar (a magnetic subtype of CV), almost all observed characters of CVs are from the physical processes and interaction between all parts of CVs. In recent 20 years, the studies for orbital period changes have been neglected, which is caused by the invalid results from the low precision of photometric data and the observational difficulty for the faint CVs. On the other hand, the spectroscopic data are also disappointed because CVs include many light sources which are hardly distinguished and cause badly pollution, deviation and broadening in spectrum and even stem from the accurate analysis of radial velocity curve. Therefore, in order to make a valid study at present, the photometric or spectroscopic data with high precision are needed. Using the telescopes in China, this paper makes photometric observations for the analysis of orbital period changes of the eclipsing CVs. At first, a complete catalogue of eclipsing CVs including 108 objects is obtained via lots of investigations and statistics. Then, Based on this catalogue, ten representative eclipsing CVs (Novae DQ Her and T Aur, Dwarf Novae U Gem, Z Cha and V2051 Oph, Novae-like AC Cnc, V363 Aur, RW Tri, SW Sex and UU Aqr) are observed and analyzed. At the same time, for the better understand of CVs, this paper still investigates the eclipsing pre-CVs in detail, and makes an analysis of orbital period changes and absolute parameters for an important object - HW Vir. Based on the works of analysis of orbital period changes and statistics for the 11 samples, we obtain three conclusions as follows: 1. According to the studies of orbital period changes on two SW Sex-type stars - SW Sex and UU Aqr, which are located in the range of 3h |
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