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Spectroscopic and photometric investigation of selected hot stars
Oplištilová, Alžběta ; Harmanec, Petr (advisor) ; Pribulla, Theodor (referee)
To rigorously study hot stars, we need to determine their properties as accurately as possible. This thesis focuses on improving the accuracy of parameters of two hot stars and contributes to the collection of stars with more known parameters. While photometric and spectroscopic data sets on hot stars δ Ori A and ω CMa are plentiful, the former is a triple star that suffers from having a faint spectrum of the secondary, which complicates its analysis, and the latter is a Be star, the origin, formation, and long-term variability of whose gaseous envelopes (veils) remain unexplained. Using mathematical techniques (Fourier transforms) and modelling software PHOEBE 1, properties of δ Ori A are determined, and conjecture on the presence of a circumstellar envelope in δ Ori A might be true by considering the shape changes of the Hα line. A conjecture that period changes of ω CMa correlate to the mass of the circumstellar envelopes seems to be proved true by considering variations of radial velocities, V/R ratio, and determining profile line asymmetry. 1
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An analysis and solution of the light curves of the massive triple star δ Orionis
Oplištilová, Alžběta ; Harmanec, Petr (advisor) ; Zasche, Petr (referee)
This bachelor thesis deals with δ Orionis A, a triple star from the multiple star system δ Orionis (Mintaka) in the constellation of Orion. This triple star consists of an eclipsing binary with the orbital period P = 5.732436 d and a distant tertiary with an orbital period in the order of several thousands of days. Even though the spectral lines of the secondary are very weak in the optical spectrum, they can be detected using a special analysis technique in the program KOREL. This work is based on a series of photometric and spectroscopic observations of changes in the brightness. The spectroscopic data come from the Ondřejov observatory and the photometric data are from several different photometers on artificial Earth satellites: SMEI, MOST and BRITE. Using spectroscopic data analysis software suite it was possible to determine the eccentricity e = 0.07590 and the mass ratio q = 0.44963. The parameters of the eclipsing binary were determined with the help of the eclipsing binary modelling software PHOEBE 1 that can process the light curves (photometry) as well as the radial velocity curves (spectroscopy). The residuals of light curves, or the deviations between the theoretical model and observation, were separated from the local solution and using the Stellingwerf statistics, one of the Phase...
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