Third components with elliptical orbits in the eclipsing binaries

Abstract

In our research, we studied 9 eclipsing binary stars: AR Lac, U CrB, S Equ, SU Boo, VV UMa, WW Gem, YY Eri, V0404 Lyr, HP Aur. We collected large sets of moments of minima from BRNO and observational data from AAVSO databases. Then, we obtained moments of minima for AAVSO observations (totally -397 minima) using method of approximation with symmetric polynomial, realized in software MAVKA. This software was provided by Kateryna D. Andrych and Ivan L. Andronov. After we combined obtained moments of minima with data taken from BRNO and plotted O-C diagrams. For all stars these diagrams represented sinusoidal-like oscillations with superposition of linear (for SU Boo, VV UMa, WW Gem, V0404 Lyr and HP Aur) or parabolic trend (for AR Lac, U CrB, S Equ and YY Eri). The oscillations could be described as presence of the third component, which does not take part in eclipses, but causes the well-known light-time effect (LTE). That effect could be easily detected using long data series of observations. However, the oscillations have clear asymmetry, which we interpreted as elliptical shape of the third components orbit. Parabolic trend we explained as mass transfer between components of binary system. For all stars we computed minimal possible mass of the third component. In addition, we developed our own code in computed language Python and using it we computed orbital elements of the third component. Moreover, for stars with parabolic trend we calculated rate of the mass transfer. Finally, for all computed values we estimated errors.В нашому дослiдженнi ми вивчили 9 затемнюваних подвiйних зорь: AR Lac, U CrB, S Equ, SU Boo, VV UMa, WW Gem, YY Eri, V0404 Lyr, HP Aur. Ми зiбрали великi масиви мiнiмумiв iз BRNO та спостережень iз бази даних AAVSO. Потiм ми отримали моменти мiнiмумiв для спостережень AAVSO (всього -397 мiнiмумiв) за допомогою методу апроксимацiї з симетричним полiномом, реалiзованого в програмi MAVKA. Це програмне забезпечення надали Катерина Д. Андрич та Iван Л. Андронов. Пiсля того ми поєднали отриманi моменти мiнiмумiв iз даними, отриманими з BRNO, та побудували дiаграми O-C. Для всiх зорь цi дiаграми представляли собою подiбнi до синусоїдальних коливання з суперпозицiєю лiнiйного (для SU Boo, VV UMa, WW Gem, V0404 Lyr та HP Aur) або параболiчного тренду (для AR Lac, U CrB, S Equ та YY Eri). Коливання можна описати як наявнiсть третього компонента, який не бере участi в затемненнях,