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Study of the eclipsing binary systems showing the inclination change
Ševčíková, Klára ; Zasche, Petr (advisor) ; Harmanec, Petr (referee)
The presented thesis is focused on the study of eclipsing binaries showing inclination changes of orbital plane. This orbital precession effect is probably caused by the presence of a third body in the system. Our method is using the study of changing eclipse depth, which allows to independently estimate parameters of the inner system and also to set some constraints on the parameters of third body. In the thesis there were analysed in detail 3 eclipsing binaries using photometric data taken from MACHO and OGLE I-IV catalgoues and from DK154 telescope observations. For the system OGLE-LMC-ECL- 10338 the nodal period was around 115 years, outer body orbits inner binary probably with period <100 days and its mass is <1,38 M⊙. For the system OGLE-LMC-ECL-10413 the nodal period was around 168 years, outer body orbits probably with period <90 days and its mass is <1,50 M⊙. For the system OGLE-LMC-ECL-14394 the nodal period was around 118 years, outer body orbits probably with period <450 days and its mass is <3,12 M⊙. 1
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Doubly-eclipsing systems
Šándorová, Ivana ; Zasche, Petr (advisor) ; Wolf, Marek (referee)
Title: Doubly-eclipsing systems Author: Bc. Ivana Šándorová Institute: Astronomical Institute of Charles University Supervisor: doc. RNDr. Petr Zasche, Ph.D., Astronomical Institute of Charles University Abstract: The study of doubly-eclipsing systems also brings new knowledge about quadru- ple stellar systems as such. And therefore the goal of our work was to create an algorithm for detecting candidates for doubly-eclipsing systems. We had photometric data avail- able from the OGLE project from the Small Magellanic Cloud. After evaluating all the data with our semi-automatic program we selected 74 objects which were further ana- lyzed in PHOEBE. We have obtained 11 new candidates for doubly-eclipsing systems for which we were able to derive both eclipse periods (other 15 candidates in SMC are already known). This gives us only 0.3 % of all binary stars in the SMC for candidates for doubly-eclipsing systems. Out of the 11 new candidates, we detected some variations indicating a common orbit for 6 of them based on the analysis of the O - C diagrams, namely: OGLE SMC-ECL-1086, OGLE SMC-ECL-2339, OGLE SMC-ECL-2515, OGLE SMC-ECL-3075, OGLE SMC-ECL-4756 and OGLE SMC-ECL-6093. Their mutual or- bital period was obtained in the range of 4 to 15 years. This means that these candidates are probably bound 2+2 systems....
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Spectroscopic study of eccentric eclipsing binaries
Lipták, Jozef ; Wolf, Marek (advisor) ; Zasche, Petr (referee)
Close eccentric eclipsing binary star systems are important to our understanding of stellar formation and evolution. We analyze three such systems - V335 Ser, BW Boo and DR Vul - with emphasis on a possible third body in the systems needed for the system's existence according to the current theoretical models. Using spectra from the Ondřejov Observatory, we attempted to disentangle the spectra of the components and determine the radial velocity solutions for the systems. For V335 Ser we obtain new radial velocity measurements, spectra, and upper limits on the mass of a possible third body. For BW Boo we obtain the spectrum of the third body possibly dynamically connected with the system. Using measured radial velocities and our fit to TESS photometry, we compute best to date parameters for the components and the orbit of the binary system. In the system DR Vul we confirmed the third body and also its nature by obtaining its spectra. We present the first orbital solution available for the central binary. The triple system does not seem to follow the theoretically predicted common inclination of the orbits. 1
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Study of inclination change for the eclipsing binaries
Juryšek, Jakub ; Zasche, Petr (advisor) ; Brož, Miroslav (referee)
This thesis deals with the study of the eclipsing binaries with inclination changes, caused by orbital precession due to third body in the system. Methods of semiauthomatic detection of the inclination changing eclipsing binaries among huge lightcurves databases have been developed. These methods have been applied to the ASAS-3 and OGLE III LMC databases. As a result, 39 new systems suspected of orbital precession have been found and 33 of them are situated in the Large Magellanic Cloud, with only one previously studied system. Increasing the number of known multiple systems especially those located outside Milky Way allows to study inter-galactic differences in star formation. In this work, we bring detailed study of ten new systems and restrictions on the third body parameters are presented. Powered by TCPDF (www.tcpdf.org)
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The light-curve solution of an eclipsing binary
Procházka, Ondřej ; Zasche, Petr (advisor) ; Wolf, Marek (referee)
The main aim of this work was the first detailed analysis of an eclipsing binary system V641 Aur. The complete light curve of this binary was obtained in three photometric filters, which were analyzed with the program PHOEBE. It is a double star with the orbital period of about 0.50487 day, whose both components are rather similar. Their individual spectral types are probably F6 and F8 (according to the temperatures), or F6 and F6 (as derived from masses). Both are orbiting on a circular orbit and despite their short period the system is a detached one and both components are still located on the main sequence. Moreover, thanks to the asymmetry of the light curve there was discovered a spot on the surface of the primary component, and the third light was not detected. For more detailed analysis higher accuracy of photometry and spectroscopy data are required.
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The light curves of eclipsing binaries
Korda, David ; Zasche, Petr (advisor) ; Wolf, Marek (referee)
New CCD photometric observations of ten short-period LMB (Low Mass Binaries) were carried out. Data were obtained using 65 cm telescope in Ondřejov in the filters I, R and V from 2014 to 2016. Light curves were analysed using the program PHOEBE. The obtained masses and radii of the stars were compared with the theoretical mass-radii relation. There arises that the short-period binaries have the radii of about 4 % larger than the theoretical prediction from the stellar evolution models. Powered by TCPDF (www.tcpdf.org)
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The evolution of stars with various masses
Cibulková, Helena ; Brož, Miroslav (advisor) ; Zasche, Petr (referee)
In the present work we study changes of the structure of a star that occur during stellar evolution and the dependence of these changes on the initial mass of the star. Internal changes affect also characteristics of the star which are observable from the outside like the effective tempe- rature or luminosity. At first we briefly derive basic equations of the stellar structure which describe the most important processes inside the star. We assume the star is nonrotating and spherically symmetric. For a detailed description of the stellar evolution, we plot individual quantities for different initial masses (from 0,1 to 100 M⊙). We use the program EZ2 for numerical calculations which enables to model the stellar evolution as long as the condition of the hydrostatistic equilib- rium is satisfied. Finally, we use the theory of the stellar evolution to determine the ages of two open clusters NGC 188 and M 45 using the method of isochrones. Keywords: stellar evolution, Hertzsprung-Russell diagram, equations of stellar structure, pro- gram EZ2 1
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