(O-C) Variations of Eclipsing Binaries in Multiple Stellar Systems

In There are inventoried 308 eclipsing systems among 1,158 multiple systems listed in Tokovinin (1997, 2007)'s multiple system catalog. Their characteristics of (O-C) variations for 83 systems among the 308 systems, which have timings of minimum lights enough to see the trends of their period changes, were investigated with the Kreiner, Kim and Nha (2001)'s recent database of times of minimum lights of eclipsing binaries. It is found that the (O-C) variations for 39 systems, corresponding to 47% of the investigated 83 systems, does not show any anticipated light-time effects (hereafter LITE) at all. Among the rest 44 systems 7 systems with apsidal motion also have a single LITE. Only 6 systems have a single LITE or double LITEs. The rest 31 systems show a secular variation superposed on a single or double or more LITEs or very complicated variation patterns. Some possible explanations for their diverse differentiation of variation are discussed.