Photometrical and statistical investigation of twin binary stars in the ASAS catalog

In existing studies on the spectral type distribution of twin binary stars, twin systems have been identified, taking into account the mass ratios found in the spectral orbit parameters of the binary stars studied. In this thesis, twin stars with light curves in ASAS were identified and photometric methods were used to identify twins. In order for a binary star to be regarded as a twin binary, the mass ratios of their components should be close to one (q≥0.95). There are 36 binary stars in the literature that are found to be twin binary stars. Since these systems have many selection effects, twin binary stars are needed on a data set free of selection effects. With this thesis study, the number of known twin stars has been increased and their distributions according to their spectral types have been determined. To do this, Algol types were extracted from all binaries (11062) in the ASAS catalog, and the primary and secondary minimum depths (470) were determined. Among these 470 twin candidates, those than can be observed in our country (240) are extracted and their light curves were analyzed. As a result of the light curve analysis, 54 systems with temperature and radius ratios between 0.95 and 1.05 were considered as twin and multi-color photometric observations were made with the TUG T100 telescope to determine the true colors without interstellar reddening. Spectral types were determined using color-color diagram of 20 twin stars whose observations among 54 twin stars were completed during this thesis. The distribution of spectral types was examined and no condensation was detected in any spectral type. It is noteworthy that there is no O-type and M-type system in our data set. However, it is necessary to include the spectral types of the other 35 twin pairs, which have been observed but the reduction and analysis process could not be completed, for a more reliable statistical conclusion. KEYWORDS: Twin binary star, Eclipsing binary star, Fotometric analysis, ColorColor diagram.