Eclipse timing variations of evolved eclipsing binaries: potential targets for meter-sized telescopes in the light of TESS observations

Abstract

. Evolved eclipsing binaries, featuring a white dwarf or a subdwarf companion on relatively short orbital periods of a few hours, exhibit interesting characteristics in their eclipse timing variations (ETV), analysis of which brings several advantages. Firstly, their small total masses enable us to detect substel-lar mass objects by observing the light-time effect, due to a subtle wobbling of the binary system around the barycenter. Additionally, the short orbital periods of these binaries allow for the accumulation of a large dataset comprising numerous observations, facilitating rigorous analysis and enhancing statistical significance. Moreover, their minima profiles have symmetric V-shapes in most cases, which decrease the uncertainties in the measurements of minima timings. In this study, we collect and analyze all available photometric data from the Transiting Exoplanet Survey Satellite (TESS), using observation cadences of both 20 and 120 seconds for such systems identified by various surveys. Our sample includes more than 60 evolved eclipsing binaries, whose primaries are either white dwarf or subdwarf companions. By calculating mid-eclipse timings, we construct detailed ETV diagrams and apply the Lomb-Scargle period analysis to determine the amplitudes and periods of their ETVs.