Photometric analyzes of some CAB candidate binary stars

In this thesis, we studied high-resolution spectra and photometric data of three CAB (Chromospherically Active Binaries) candidates stars (CF Tuc, KZ Pav and WZ Hor), which were obtained at the Mt John University Observatory in New Zealand in 2007 and 2008. We used some photometric data of these stars from literature.We analyzed the high-resolution spectra of CF Tuc with two different methods (cross-correlation and KOREL). Radial velocities of both components were obtained, and the spectroscopic orbit of the system was solved. The H? and CaII H & K emission lines of CF Tuc were studied. Using almost simultaneous spectroscopic and photometric observations, an anticorrelation between the H? emission and the BV light curve maculation effects was found. It is concluded that the components rotated synchronously according to their Na D2 line profiles. Our spectroscopic data and recent BV light curves were solved simultaneously using the Wilson-Devinney method. The following absolute parameters of the components were determined: M1=1.11±0.01 M?, M2=1.23±0.01 M?, R1 =1.63± 0.02 R?, R2 =3.60± 0.02 R?, L1 = 3.32 ± 0.51 L? ve L2 = 3.91 ± 0.84 L?. The primary component has an age of about 5 Gyr, and the positions of the components in the HR diagram were also discussed. The distance to the system was estimated to be 89±6 pc from the dynamic parallax, neglecting interstellar absorption. The orbital period of the system was studied using the O-C analysis. The O-C diagram could be interpreted in terms of either two abrupt changes or a quasi-sinusoidal form superimposed on a downward parabola. These variations were discussed by reference to the combined effect of mass transfer and mass loss, the Applegate mechanism and also a light-time effect due to the existence of a third body in the system. The Hipparcos astrometric data was also analysed.High-resolution spectra of CCDM J20587-7025 A eclipsing binary component of the KZ Pav (IDS 20490?7048 A-BC) multiple system were analyzed with two different methods (cross-correlation and KOREL). Radial velocities of the components of the binary were derived, and the orbital parameters of the binary were calculated. The close binary components rotated synchronously according to their MgI (5183.6 Å) line profiles. The new radial velocities and four photometric data sets (1988?89 BV, 1998 V, Hipparcos and 2006 BVRI) were analyzed simultaneously using the Wilson-Devinney method. The absolute parameters of the components were calculated as M1=1.70±0.02 M?, M2=1.09±0.03 M?, R1 =1.74± 0.01 R?, R2 =1.94± 0.02 R?, L1 = 5.86 ± 0.81 L? ve L2 = 2.32 ± 0.40 L?. The primary component has an age of about 1.4 Gyr, and the positions of the components in the HR diagram were also discussed. The distance to the system was estimated to be 115±8 pc from the dynamic parallax, neglecting interstellar absorption. The variation of the orbital period of KZ Pav A, from times of minimum data covering nearly one century, indicates a quasi-sinusoidal form superimposed on a downward parabola. The secular period decrease was interpreted in terms of the combined effects of mass transfer and loss. The sinusoidal component may reflect a light-time effect from either an unseen component or higher order terms in perturbations from the BC system, or perhaps an internal magnetic field rearrangement (Applegate type) mechanism. The orbits of the A-BC and B-C systems are considered against historic astrometric measurements.We present the first spectroscopic study and the first ground-based photometric observations of WZ Hor. High resolution spectra of the system were analyzed with using cross-correlation and KOREL, and only the radial velocity values of the primary component were derived. The photometric BVRI light curves were solved simultaneously using the Wilson-Devinney method with Monte Carlo type algorithm. The photometric mass ratio was derived as q=0.403. The following absolute parameters of the components were estimated from the spectral mass function and the photometric solution: M1=1.94 M?, M2=0.77 M?, R1 =1.84 R?, R2 =0.75 R?, L1 = 5.24 L? ve L2 = 0.11 L?. The positions of the components in the HR diagram were also discussed.Keywords: binaries: eclipsing- stars: fundamental parameters ? technique: spectroscopy ? technique: photometry ? stars: individual (CF Tuc, KZ Pav and WZ Hor).