Dwarf novae are a type of binary star system that consists of a cool red dwarf, as well as a white dwarf with an accretion disk. Occasionally the disk will get significantly brighter for a few days in an event called an outburst. On February 6th, 2002 one such system, CN Orionis, was experiencing such an outburst. The goal of this research was to determine some important characteristics of CN Orionis during its outburst. This thesis will present the light output, temperature, and the area of the accretion disk of CN Orionis. / Department of Physics and Astronomy

Dwarf novae are a type of cataclysmic variable in which one of the components is a white dwarf. Their outbursts can range in brightness from two to five magnitudes at intervals that can vary from days to decades. The purpose of this study is to analyze the outburst of SS Cygni on the nights of June 18-22, 1987. Using an Interactive Reduction Software (IRS) package and a Gaussian fit program, the emission and absorption line strengths on the rise to outburst showed an increase in the flux as well as various other details supported by theory. / Dwarf novae -- Accretion disk -- SS Cygni -- Data analysis and results. / Department of Physics and Astronomy

The focus of this study is the change in accretion disk size in Dwarf Novae (DN), IP Peg. DN systems are a type of cataclysmic variable that experience periodic outbursts. These outbursts are caused by the release of gravitational potential energy from an increased rate of matter flow through the accretion disk. Throughout outburst, the radius of the accretion disk of the DN changes. Recent research done at Ball State University has suggested that the disk radius may not change as the disk instability model predicts. According to the disk instability model, the accretion disk should be at its largest radial size when the DN is at the peak of outburst. IP Peg in September and October of 2006 underwent outburst. It was found that during that particular outburst that the accretion disk was at its largest radial size on the decline from outburst and not peak. Further research into how the accretion disk changes with time is needed. / Department of Physics and Astronomy

IP Peg is a member of a family of star systems known as cataclysmic variable stars, CVs. CVs are star systems in which a red dwarf star orbits a white dwarf and mass transfer is taking place from the red dwarf to the white dwarf. The mass ratio of the two component stars has been found the most difficult parameter to determine. Tools used in the analysis of mass-ratio included the differential photometric light curve of IP Peg, Doppler tomograms, and spectral data covering the HP emission-line. The mass ratio was found to lie in the range, q = 0.44 ± 0.14. The inclination lies in the range i = 81.5° ± 8.5°. Finally, the accretion disk radius was 0.342 times the distance between the stars. The analysis of the parameters of eclipsing CV systems like IP Peg provides a rare opportunity that helps in the understanding of other CV systems. / Department of Physics and Astronomy

There is no abstract available for this thesis. / Department of Physics and Astronomy

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22248号 / 理博第4562号 / 新制||理||1655(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 野上 大作, 教授 嶺重 慎, 教授 長田 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Photometry of eclipsing dwarf-nova EX Draconis was performed at the observatory of Astronomical Institute of the Academy of Sciences of the Czech Republic in Ondřejov and at the Astronomical Observatory on Kolonické sedlo during 63 nights. I calculated times of minimum light by two methods - the mirror method and the derivative method. The mirror method is more precise for these measurements with longer exposure time and smaller coverage of the light curve of eclipse. 53 new times of minima calculated by the mirror method and times of minima obtained from the older articles about EX Dra were included in the O-C diagram and fitted by the sine function and theoretical curve of LITE caused by an unseen third body. Period of cyclic changes for the sine function is 25 years, instead of 4 or 5 years period given in older papers.Period of the third body orbit is aproximately 17 years and its minimum mass is 53.5 Jupiter's mass. The sum of squared deviations is 5 times smaller for the LITE, which means that the LITE ilustrates the O-C diagram better. I determined the average outburst period for three observational seasons and I drew the phase curve of outburst. Finally, I calculated the short period of the light changes outside eclipse.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23014号 / 理博第4691号 / 新制||理||1673(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 野上 大作, 教授 嶺重 慎, 教授 太田 耕司 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM